University of Southern California Dissertations and Theses

Sleep problems, sensory difficulties, and social participation in children with autism spectrum disorders

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Sleep problems, sensory difficulties, and social participation in children with autism spectrum disorders

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Content SLEEP PROBLEMS, SENSORY PROCESSING DIFFICULTIES, AND
SOCIAL PARTICIPATION IN CHILDREN WITH AUTISM SPECTRUM
DISORDERS

by

Chia-Chen Wu

_______________________

A Thesis Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OF ART
(OCCUPAITONAL SCIENCE AND OCCUPATIONAL THERAPY)

May 2007

Copyright 2007 Chia-Chen Wu

ii
Dedication

I would like to dedicate this thesis to my Lord, Jesus Christ, my beloved
father, Jeng-Chuan Wu, and my sister, Chia-Jung Wu.

iii
Acknowledgements

I would like to acknowledge and express my sincere appreciation to the
following people for their help in this thesis.
A little girl and a mother who originally inspired me to decipher the relationships
between sleep and behavior.
Dr. Parham, thesis chair
Dr. Clark, Dr. Wincor, and Dr. Neville-Jan, committee members
Dr. Carlson, research consultant
Zoe Mailloux and Gina Coleman, PTN administration
Angee Sipes, Annie Baltazar, Chanda Chadda, Dan Schakel, Elaine Chou, Joan
Surfus, Kim Kalmanson, Melissa Vindigni, Mollie Chainani, Monica
Mathur, Neeha Patel, Odessa Alpuerto, Stefanie Bodison, and Valerie
Rougeau, therapists at PTN who helped in the data collection
The parents and children of PTN
Michael Plesset, a good friend of mine
Every friend of mine who prayed for me

iv
Table of Contents
Dedication ii
Acknowledgements iii
List of Tables vi
List of Figures vii
Abstract viii
Preface ix
Chapter I: The Problem 1
Introduction 1
Purpose of the Study 5
Research Questions and Assumptions 5
Rationale 6
Research Design 7
Significance of the Study 9
Chapter II: Review of Literature 11
Introduction 11
Section I: Autism Spectrum Disorders 11
Diagnoses and Prevalence of ASD 12
Sensory Integration in children with ASD 13
Section II: Basic Concepts of Sleep 15
AMacroscopic Perspective of Sleep 15
Sleep Stages 16
Methodologies in Sleep Studies 19
Functions of Sleep 20
Section III: Sleep Patterns and Sleep Problems in People with ASD 25
Sleep in Typical Developing Children 25
Sleep in Children with Autism Spectrum Disorders 27
Sleep Patterns and Behavioral Problems in People with ASD 28

Chapter III: Methods 56
Overview of the Study 56
Participants 57
Instruments 58
Procedure 61
Data Analysis 62

Chapter IV: Results 65
Description of Participant’s Characteristics 65
Sleep Patterns 69
Correlations among Measures 77
v
Chapter V: Discussion 80
Interpretation and Implications of Findings 80
Clinical Significance 88
Limitations 90
Suggestions for Future Studies 92

References 94

Appendices
Appendix A: Definition of Terms 103
Appendix B: Flyer 110
Appendix C: Informed Consent 111
Appendix D: Sleep Medical History Form 115
Appendix E: Child’s Sleep Habit Questionnaire 116
Appendix F: Data Collection Tables 119

vi
List of Tables
Table 1: Significant Differences of Sleep Parameters in Subjects
with ASD on Subjective Measures, Compared to
Typically Developing Subjects 47

Table 2: Significant Differences of Sleep Parameters in Subjects
with ASD on Objective Measures, Compared to
Typically Developing Subjects 49

Table 3: Associations between Sleep Problems and Waking Behaviors
in Subjects with ASD on Subjective Measures 51

Table 4: Associations between Sleep Problems and Awakening Behaviors
in Subjects with ASD on Objective Measures 54

Table 5: Demographic Characteristics of Participants 66

Table 6a: Sleep Characteristics Obtained from the Sleep Medical History
Questionnaire and the CSHQ 67

Table 6b: Amount of Night Sleep and Duration of Night Waking Obtained
from the CSHQ 68

Table 6c.The CHSQ Total and Subscale Scores 68

Table 7: Sensory Processing Difficulties and Social Participation 69

Table 8: Numbers and Percentages of Children Whose Parents Reported
with a Yes on Each Item of the CSHQ 73
Table 9a: Between-Group Comparisons of Median CSHQ Total and
Subscale Scores 75

Table 9b. Within-Group Comparisons of Median CSHQ Total and
Subscale Scores 76

Table 10. Between-Group Comparisons of Mean Amount of Night Sleep
and Duration of Night Waking 76

Table 11. Correlations(r) among Variables 79

vii
List of Figures
Figure 1: Two-Process Sleep Model in Humans 18
Figure 2: Percentages of Children on the Presence of Sleep Disturbances 74

viii
Abstract

The aim of this pilot study is to investigate the prevalence and patterns of
sleep problems in a clinical sample of children aged from 5 to 9 years and 4
months with autism spectrum disorders, and to explore currently unclear
associations among sleep problems, sensory processing difficulties, social
participation, and chronological age. Surveys including the Child’s Sleep Habit
Questionnaire (CSHQ), the Sensory Processing Measure Home Form-R (SPM
Home Form-R), and a researcher-generated sleep medical history form were
given to parents of participants during their visits in a sensory-based occupational
therapy program in a private clinic. Thirty three children with a mean age of 6
years and 6 months were sampled. Seventy eight percent of children had sleep
problems determined with the CSHQ cutoff score. Sleep patterns in children for
whom sleep problems were consistently indicated both on CSHQ total score (G
41) and parent responses on the sleep medical form were more bedtime resistance,
less overall sleep duration, and frequent night waking. Chronological age was
positively significantly associated with overall sensory functions, but negatively
significantly associated with overall sleep problems, night waking, and daytime
sleepiness. Moreover, the longer the children slept at night, the better their
vestibular functions were. The longer duration that children woke at night, the
worse their proprioceptive function was. The more severe parasomnias the
children had, the worse their social skills were. These findings not only affirm
sleep is related to daily behavior and further to the engagement in occupations in
this particular population, but also indicate compelling clinical implications.
Further studies are strongly recommended.
ix
Preface

This topic first came to my mind when I treated a little girl who had both
autism and a sleep disorder. Her wise mother, later on becoming one of my best
friends, carefully monitored her sleep as well as her daily behavior. At that time
we always tried to find possible connections between these two.
The topic next came to me when Dr. Blanche talked about distortion of
occupational orchestration which means the flow of occupation is disorganized
by any possible cause. The concept of the possibility of connecting sleep with
engagement in daily occupation popped up again into my head.
Because of those two occasions, this topic was formed.
Besides them, two verses strengthened me to make this project come true.
“When you lie down, you will not be afraid;
yes, you shall lie down and your sleep shall be sweet.”
- Proverb 3:24 (Amplified Version)
“In peace I will both lie down and sleep,
for You, Lord, alone make me dwell in safety and confident trust.”
- Psalm 4:8

I hope this project will not only be able to enrich occupational therapy, but
also expand our perspective of time in human behavior from daytime to the
whole day as Reed described time to occupational therapy as follows:
past, present and future as well as the 24-hour day in organized habits of
work, rest, play and sleep.

1
Chapter I: The Problem

As a problem is uncovered, the desire to know more grows. In this chapter,
the problem is presented by the descriptions in the introduction, purpose of the
study, research questions and assumptions, rationale, research design, and
significance of the study. As it is explored more deeply, sleep in children with
autism spectrum disorders becomes progressively more interesting.

Introduction
Children with autism spectrum disorders are not only limited by their
impairments in social interaction, in communication, and in repetitive patterns of
behaviors, but also suffer from other difficulties, such as sleep problems, poor
self regulation, and tactile hypersensitivity (Honomichl et al., 2002). Sleep
problems are especially noteworthy because they not only increase parental stress
(Honomichl et al., 2002), but also influence children’s daytime behavior
(Hoffman et al., 2005; Malow et al., 2006; Patzold et al., 1998; Schreck et al.,
2004). Sleep problems are estimated to occur in 44% to 83% of children with
autism spectrum disorders (Honomichl et al., 2002; Patzold et al., 1998; Richdale,
1999). Moreover, sleep problems may exacerbate symptoms of autism spectrum
disorders (Hoffman et al., 2005; Schreck et al., 2004).
Despite the high prevalence of sleep problems among children with autism
spectrum disorders, and the potential impacts of them on these children and their
parents, pediatric occupational therapists seldom consider that sleep problems
2
may interfere with these children’s engagement in occupation, compared to
another underlying factor, sensory processing problems. There are three
compelling reasons for occupational therapists to study the influence of sleep on
the daytime behavior and functions of children with autism spectrum disorders.
First, the occupational therapy practice framework clearly states that sleep is a
domain of concern in occupational therapy (AOTA, 2002). It is categorized as
falling within the area of activity of daily living (ADL).
Second, problem sleep in children with autism spectrum disorders is a
factor affecting their daytime behavior and functions. Studies of children with
special needs as well as typically developing children have shown that the quality
and quantity of their sleep influence daytime functions (National Institute of
Health, 2003), such as social skills (Beth et al., 2006; Hoffman et al., 2005;
Patzold et al., 1998; Schreck et al., 2004), learning (Dahl, 1996a), memory
(Walker, 2005), attention (Chervin et al., 2002; Malow et al., 2006), and copying
performance (Suzuki et al., 2005). Studies of children with autism spectrum
disorders have also shown some general relationships between sleep problems
and negative daytime behaviors including over-activity (Hoshino et al., 1984),
disruptive behavior (Patzold et al., 1998), communication difficulties (Segawa et
al., 1992), and social difficulties (Hoffman et al., 2005; Malow et al., 2006;
Schreck et al., 2004; Segawa et al., 1992). Therefore, in order to thoroughly
understand children’s behavior and functions, the influence of sleep should be
considered. This understanding may help occupational therapists not only
clinically reason sleep as an underlying factor of children’s daytime performances
when making treatment plans, but also consider increasing the quality of
3
children’s sleep as one of the treatment goals in order to increase their daytime
functions and therefore to enhance their engagement in occupation.
Third, very little literature in occupational therapy (OT) examines the
relevance of sleep problems to occupational participation in children with autism
spectrum disorders. In the occupational therapy literature on children with special
needs, few publications refer to or describe sleep problems. Stewart and Meyer
(2004) studied feeding and sleep routines in parent-child interactions in children
with failure to thrive and found that although only 2 of the 5 mothers
participating in this study showed concerns over their children’s problem sleep,
sleep measurements showed 4 of the 5 children had irregular sleep patterns,
compared to typically developing children. Leone and Rogers (2001) suggested
that having a proper bedtime environment, such as a soft light on or soothing
object in bed, and setting proper bedtime routines, such as a certain set of
activities or slow rocking before bedtime, might help children with autism
spectrum disorders fall asleep because these strategies would provide calming
sensory inputs. In other words, by using these sensory strategies, sleep
disturbances in these children may be reduced or eliminated. In her discussion of
children with impairment in self regulation, DeGangi (2000) indicated that
sensory processing difficulties might involve sleep problems. She described
several case studies to illustrate that treating children with sensory processing and
sleep problems by using a sensory based approach would also improve their sleep.
In addition to her suggestion of having regular daily routines and applying
sensory strategies on a daily basis, she also suggested parents and caregivers need
to be emotionally supported when dealing with children’s sleep issues. Spitzer
4
and Roley (2001) mentioned that irregular sleep patterns might be the result of
impairment in sensory integration functions. Therefore, in the occupational
therapy literature, sleep problems are thought to be related to sensory processing
problems. In order to accumulate more information about sleep and its
relationship with sensory processing in occupational therapy, this pilot study aims
to primitively investigate the relationship between sleep problems and sensory
processing in children with autism spectrum disorders.
Another factor, social participation, was included in this pilot study due to
several reasons. First, social skill difficulty is a diagnosed impairment in children
with autism spectrum disorders. Moreover, studies on sleep problems in children
with autism spectrum disorders have shown that some of the sleep problems, such
as sleep duration, parasomnias, and hours slept per night are related to social
skills in this population (Hoffman et al., 2005; Schreck et al., 2004). Furthermore,
increasing engagement in activities involving interpersonal interactions in daily
events and environments is one of the ultimate goals for pediatric occupational
therapists treating this particular type of children. Therefore, social participation
was chosen as a factor related to the engagement of occupation in our study.
Although social participation in our study is defined as activities associated with
organized patterns of behavior that are characteristic and expected of an
individual or an individual interacting with others within a given social system
(AOTA, 2002), the instrument we used in this study to measure social
participation contains questions involving both child’s participation in
occupations as well as child’s social skills.

5
Whether sleep problems, sensory processing difficulties, and social
participation are related in children with autism spectrum disorders hasn’t been
examined in occupational therapy. Thus, in order to explore sleep problems in
this population and to primitively investigate the relationships among sleep
problems, sensory processing difficulties, and social participation, this pilot study
was formed.

Purpose of the Study
The purpose of this pilot study was to explore sleep problems in a clinical
sample of children with autism spectrum disorders and to investigate the
relationships among social participation, sleep problems, sensory processing
difficulties, and chronological age.

Research Questions and Assumptions
Research questions
1. In a clinical sample of 33 children aged 5 to 9 years and 4 months with
autism spectrum disorders referred to occupational therapy, what is the
prevalence of sleep problems?
2. In this sample, what are common sleep patterns?
3. Are sleep problems and sensory processing difficulties negatively
correlated with social participation? Are sleep and sensory processing
problems negatively correlated with chronological age?

6
Assumptions
1. Regardless of whether medication is involved, the quality and quantity
of sleep impacts human daily functions.
2. Although sleep is not an occupation, sleep influences engagement and
orchestration of occupation.

Rationale
Over 50% of children with autism spectrum disorders have difficulties in
sleep initiation and maintenance (Honomichl et al., 2002; Patzold et al., 1998;
Richdale, 1999). Those difficulties are associated with their social skills,
communication disturbances, and activity level (Hoffman et al., 2005; Elia et al.,
2000; Hoshino et al., 1984; Malow et al., 2006; Patzold et al., 1998; Richdale et
al., 2000; Schreck et al., 2004; Segawa et al., 1992). Moreover, 42% to 88% of
children with autism spectrum disorders have sensory processing problems
(Baranek et al., 2005). These problems may also disturb these children’s social
skills (Case-Smith & Miller, 1999). However, compared to the influence of
sensory processing problems on social participation, the effect of sleep problems
is seldom considered within occupational therapy treatment or consultation.
Furthermore, another issue, whether sensory processing difficulties are truly
related to sleep problems, still needs to be deciphered. Therefore, in order to
further explore sleep problems in autistic children as well as document the
relationships among sleep problems, sensory processing difficulties, and social
participation in children with autism spectrum disorders who received

7
occupational therapy, data on sleep problems, sensory processing difficulties, and
social participation were collected and analyzed.
Since sleep patterns in typically developing toddlers and young children
have not reached adults’ patterns (Davis et al., 2004b), we designed to recruit
children who were 5 years old or older in order to find sleep problems specific for
children with autism spectrum disorders and also to accommodate the age ranges
set in the instruments we chose. Therefore, children with age range from 5 years
to 9 years and 4 months were sampled in our study.

Research Design
A quantitative study investigating parental perceptions of children’s sleep
problems was designed. Children whose ages were 5 years to 9 years and 4
months with autism spectrum disorders referred to occupational therapy in a
private non-profit pediatric clinic were recruited. Diagnoses in autism spectrum
disorders included autistic disorders, Asperger’s syndrome, and PDD-NOS.
Thirty three children were sampled.
Three survey forms were used. They are the Child’s Sleep Habits
Questionnaire (CSHQ), the Sensory Processing Measure Home Form-R (SPM
Home Form-R), and a researcher-generated sleep medical history form. The
Child’s Sleep Habit Questionnaire (CSHQ) is a sleep questionnaire designed for 4
to 12 year old children, who are suspected to have sleep disturbances (Owens et
al., 2000). The research edition of the Sensory Processing Measure Home Form
(SPM Home Form-R) (Parham & Ecker, in press) is a questionnaire measuring
children’s sensory processing difficulties and social participation in the home
8
environment. The social participation part in the SPM Home Form-R includes
questions about child’s participation in occupations as well as child’s social skills.
A sleep medical history form was designed by the researcher for this study to
collect data regarding sleep medical history.
Data on sleep measures were collected by the CSHQ and the sleep medical
history form. Questions in the CSHQ are related to specific sleep problems, such
as bedtime resistance, parasomnias and etc. A global question of whether parents
think in general that their children have sleep problems was designed in the sleep
medical history form to ask parents’ overall perceptions of their children’s sleep
problems. Parents or caregivers who allowed their children to participate in this
study were requested to fill out the three survey forms. After all of the data were
collected and calculated, data were entered to the researcher’s computer and
analyzed with SAS.
Data analysis was separated into three parts in order to answer the three
research questions in this study. First, using a basic descriptive approach,
participants’ characteristics including demographic, sensory processing, social
participation, and sleep problems were summarized.
In addition, sleep patterns were depicted by the presence of sleep
disturbances and the severity of sleep problems. Presence of sleep disturbances
was measured by total number of yes responses to questions parents answered on
the CSHQ. Severity of sleep problems was measured by the CSHQ subscales
scores. Participants were grouped into three groups, based on the consistency of
their sleep problems reported both on the CSHQ total score and parent responses
on the question of whether the child has a sleep problem asked in the sleep
9
medical history form. Group A is comprised of children for whom sleep problems
were consistently indicated both on CSHQ total score (G 41) and parent responses
on the sleep medical form. Group B consists of children for whom sleep problems
were inconsistently reported on the CSHQ and the sleep medical history form.
Parents of group B reported CSHQ total scores G 41, indicating sleep problems,
but answered “no” to the question on the sleep medical history form. Group C
contains children whose parents consistently indicated no sleep problems both on
CSHQ total score (<41) and the question asked in the sleep form.
Numbers and percentages were used to summarize the presence of sleep
disturbances. The Kruskal Wallis test and Wilcoxon rank sum tests with
Bonferroni adjustment were used to test the between-group and within-group
differences in the ordinal data related to the severity of sleep problems. The
ANOVA on ranks and T-test with Scheffe’s adjustment were used to test the
between-group and within-group differences in the continuous data related to
sleep problems.
Finally Spearman correlation coefficients were performed to test the
correlations among sleep problems, sensory processing difficulties, social
participation, and chronological age.

Significance of the Study
Not only are sleep disturbances in children with autism spectrum disorders
documented in the sleep literature, but also the impacts of sleep problems on
daily behavior and family life are stressed. This study may be the first in
occupational therapy to provide a detailed description of sleep patterns in a
10
clinical sample of children with autism spectrum disorders along with
information on the possible relationships between sleep patterns and other issues
that occupational therapists often stress, especially sensory processing difficulties
and social participation. Moreover, this study also introduces sleep terminology
into occupational therapy, and begins to bridge the relationship between sleep and
daily engagement in occupation. In other words, this study broadens occupational
therapists’ understanding of daytime behavior by enriching their knowledge of
nighttime behavior - sleep. Therefore, documenting children’s sleep in
occupational therapy is worthy of effort.

11
Chapter II: Review of Literature

Introduction
The fact that sleep is a behavior in every human being shows its vital role
in life. However, its influences on waking behavior were not fully revealed until
the 20
th
century, and a growing body of experimental research has gradually
unmasked its functions. This thesis is designed to help us further understand the
functions of sleep. This literature review is divided into three sections: autism
spectrum disorders, basic concepts of sleep, and sleep patterns and sleep
problems in people with ASD. In the section I, diagnoses, prevalence, and
sensory features of autism spectrum disorders are introduced. Section II contains
descriptions of some basic concepts of sleep in order to understand the
terminology used in sleep studies. Section III describes sleep studies about sleep
patterns and sleep problems in people with ASD in details. Moreover, in order to
more clearly present the findings from all of the studies presented, tables are
made.

Section I: Autism Spectrum Disorders
This section describes diagnoses, prevalence, and sensory features of
autism spectrum disorders in order to introduce the characteristics in this
particular population on which our study focused.

12
Diagnoses and prevalence of Autism Spectrum disorders
Autism spectrum disorders (ASD) are a group of disorders sharing similar
symptoms involving quality of social skills, communication, and frequency of
stereotypical behaviors, also called pervasive developmental disorders (PDD).
They are neurological disorders resulting in various dysfunctions in daily life
(Case-Smith & Miller, 1999). Although ASD includes autism disorders,
Asperger’s syndrome, pervasive developmental disorder not otherwise specified
(PDDNOS), Rett’s syndrome, and childhood disintegrated disorder (APA, 2000),
here, in this thesis, only autism, Asperger’s syndrome, and PDDNOS are included.
According to the Diagnostic and Statistical Manual of Mental Disorders (APA,
2000), children with autism have characteristics of qualitative impairments in
social interaction, impaired communication, and repetitive and stereotypical
patterns of interests, behaviors, and activities, beginning before age of 3 years.
Children with Asperger’s syndrome have qualitative impairment in social
interaction and stereotyped patterns of behaviors. Although children with
Asperger’s syndrome may speak fluently, impairments in language use in social
context are reported (Bishop & Baird, 2001). Children with PDDNOS are
characterized by qualitative impairment in social skills. Children with PDDNOS
have either communication problems or restricted and repeated patterns of
behaviors, interests, and activities.
Children with autism also combine with a range of intelligence disability.
Three quarters of them are reported to have an IQ below average (<70) (Joseph et
al., 2002), while children with Asperger’s syndrome and PDDNOS have no
significant cognitive delay. In general, children with high function autism,
13
Asperger’s syndrome, and PDDNOS have relatively better social skills, better
communication, less qualitative impairments in stereotypical patterns of interests,
behaviors, and activities, and higher cognition. .
Incidence rates of autism, Asperger’s syndrome, and PDDNOS are 2.6,
20.8, and 20.8 per 10,000 births respectively (Fombonne, 2005). The incidence
rate of autism spectrum disorders collectively is about 60 per 10,000 children
(Chakrabarti & Fombonne, 2001; Bertrand et al., 2001). The incidence of autism
in males is usually 4 to 5 times more frequent than in females. In addition to these
diagnosed characteristics, unique sensory processing features in people with
autism spectrum disorders strongly draw occupational scientists’ attention.

Sensory Integration in Children with Autism Spectrum Disorders
Sensory integration is a fundamental function for a person to be able to
manage and organize sensory information to appropriately adapt into social,
cultural, spatial, and temporal environments (Spitzer & Roley, 2001). From the
management and organization of sensory inputs to the appropriate adaptation
occurring in those environments, for children with autism spectrum disorders,
sensory processing problems deeply disturb their abilities to efficiently engage in
occupations. These disturbed abilities include attention, cognition and language,
and interaction with peers and adults (Case-Smith & Miller, 1999). Theoretically
attention and activity level are in the integration phase between sensory inputs
and responses, and the ability to concentrate is stated as an outcome of sensory
integration (Ayres, 1979). Attention, activity level, and the ability to concentrate
are also included in social skills (Riod & Miller, 1997).
14
In the literature, the prevalence of sensory integration disorders in
school-age children with ASD is approximately 42% to 88% (Baranek et al.,
2005). Sensory modulation, a subtype of sensory integration disorders, is the
second most severe problem observed, behind the diagnosed problem of social
interaction in this group of children (Case-Smith & Miller, 1999). Attention,
sensory modulation, tactile and vestibular functions, body awareness and motor
planning are frequently addressed problems in pediatric occupational therapy
(Case-Smith & Miller, 1999).
In fact, the relationship between sensory processing problems and sleep
problems has not been researched yet. However, some researchers have
mentioned a possible association between sensory processing and sleep. DeGangi
(2000) proposed that hypersensitive children and children who crave movements
might have sleep problems. Hypersensitivity to sensory inputs is a sensory
processing problem. Children who crave movements may also have sensory
processing problems. From Degangi’s observation, when hypersensitive children
and children who crave movements were treated for their sensory processing
problems, their sleep initiation and maintenance improved. She further noticed
that sensory strategies might facilitate and maintain sleep. Leone and Rogers
(2001) also proposed using sensory strategies to assuage autistic children’s sleep.
Moreover, Spitzer and Roley (2001) mentioned that irregular sleep patterns might
be the result of impairment in sensory integration functions.
Another presumption about the relationships between sleep problems and
sensory processing problems is that studies have shown that sleep is closely
associated with attention (Chervin et al., 2002), copying performances (Suzuki et
15
al., 2005), procedure motor learning (Walker, 2005), and social skills (Hoffman et
al., 2005; Limoges et al., 2005). In addition to that, being able to concentrate and
function in social context as well as being able to appropriately use the body in
special and temporal context are also outcomes of sensory processing treatment.
Therefore, sensory processing and sleep may reasonably have a possible
association. The association is worthy of more attention and study. Thus, one of
the main goals in this study is to investigate the association.

Section II: Basic Concepts of Sleep
This section contains descriptions of some basic concepts of sleep to
introduce not only sleep itself, but also the terminology in sleep literature. A sleep
theory, sleep stages, and methodologies in sleep studies are first given. Then
functions of sleep depicted in sleep literature specifically about the influence of
sleep on waking behavior are given.

A Macroscopic Perspective of Sleep
A variety of sleep theories have been developed. One of them is the
Two-Process Sleep Model which depicts two closely interacting processes
ensuring human sleep at night. The two closely interacting processes are
homeostatic and circadian sleep rhythm (Buysse, 2005; Owens, 2005). The first
process, homeostatic, is a sleep drive which gradually increases as night sleeping
approaches. The peak of the homeostatic process is the beginning of sleep. The
homeostatic process modulates the depth and length of sleep. The other process,
circadian sleep rhythm, is a biological time clock, synchronized by environmental
16
factors, mainly light. This circadian sleep factor regulates the timing and duration
of the wake-sleep cycle. Physiologically, this factor can be seen as a wake drive.
The peak of the circadian sleep rhythm is during the middle of the sleep period
and then the rhythm gradually decreases to the lowest point during the middle of
daytime wakefulness (see Figure 1).
The major nuclei regulating the circadian information are the paired
suprachiasmatic nuclei (SCN) of the hypothalamus at the base of the third
ventricle (Buysse, 2005). In response to daylight, the SCN, receiving photic
information from the eyes, transmits waking signals to the dorsomedial nucleus,
where these signals integrate behavioral and endocrine information. Next, this
integrated message excites the arousal regions and inhibits the sleep-producing
neurons, mainly located in the ventrolateral preoptic area (VLPO) (Espana &
Scammell, 2004). On the other hand, in sleep, sleep-producing neurons fire and
inhibit arousal systems (Espana & Scammell, 2004).

Sleep Stages
Sleep is a period in a 24 hour sleep-wake rhythm. In this period, patterns of
physical activity and neurobiological activity change (Buysse, 2005). These
changes can be detected and divided into several states by polysomnography
(PSG). A polysomnogram contains electroencephalogram (EEG),
electromyogram (EMG), and electroocculogram (EOG) to record brain electric
activity, eye movements, and muscle activation in sleep.
Wakefulness, rapid eye movement (REM) sleep, and non-rapid eye
movement (NREM) sleep are three neurobehavioral states in humans (Carskadon
17
& Dement, 2000). Each of them has different patterns of environmental responses,
cognitive activity, and general physiology. For example, in wakefulness, the
human has increased environmental responses, cognitive activity, and muscle
tone; however, in REM sleep, decreased environmental responses, decreased
muscle tone, and story-like dreaming mental activity can be detected. NREM
sleep is characterized by decreased environmental responses, decreased muscle
tone, and absent or limited mental activity. NREM sleep occupies most of the
first half of the night, and REM the later half (Buysse, 2005). REM sleep is often
associated with intellectual function (Smith, 1996). Low IQ is often associated
with reduced duration of REM sleep, reduced density of eye movements during
REM sleep, and increased latency of REM sleep (Espie & Tweedie, 1991; Espie
et al., 1998; Stores, 1992).
NREM sleep is further divided into four stages. Stage 1 is a transitional
stage from wake to sleep or from sleep to wake. Stage 2 is predominantly NREM
sleep. Stages 3 and 4 are slow wave sleep (SWS), and also called deep sleep.
These 4 stages have their distinctive brain waves, which can be detected by EEG.
Approximately 50% of a night’s sleep contains Stage 2 sleep. Stage 2 sleep
spindles, a type of brain wave, correspond to a protective processing (Maquet et
al., 2003). By de-activating the thalamus-cortical loops, this process helps the
brain gradually go into sleep status, in which the brain deactivates from incoming
stimuli (Steriade et al., 1993). This process is normally associated with selective
attention or planning and action (Kostopoulos, 2001). Compared to sleep effects
on waking behavior, sleep characteristics and sleep stages are relatively clearly
stated in literature.
18
Figure 1. Two-process sleep model in humans: a macroscopic perspective of
sleep models to describe two closely interactive factors: Homeostatic and
circadian sleep rhythm, ensuring human sleep at night

Note. From Sleep disorders and psychiatry (p.12), by D. J. Buysse, 2005, Washington
DC: American Psychiatric Publishing. Copyright 2005 by D. J. Buysse. Printed with
permission.

19
Methodologies in Sleep Studies
In human sleep studies, subjective and objective methods are usually used
to measure sleep (Limoges et al., 2005). In subjective methods, questionnaires
and sleep diaries are used to record and survey sleep behaviors in the passing
weeks or months. Sleep parameters in sleep questionnaires or diaries often
include light-off time, sleep onset time, sleep latency, sleep offset time, frequency
of night waking, duration of night waking, sleep quality, restlessness, total night
sleep, true sleep period, time in bed, sleep environments, sleep routines, and
frequency and duration of daytime naps. Light-off time refers to the time parents
or children turn off the light when going to bed. Sleep onset time is the time sleep
starts. Sleep latency, also called sleep onset delay or sleep onset latency, is
defined as the period of time from when a child is in bed to when the child falls
asleep. Sleep offset is the time sleep ends. Sleep quality is the satisfaction that
people have about their sleep. Total night sleep, sometimes also called sleep
period time, or sleep duration, refers to the period of time from sleep onset to
sleep offset. True sleep period, sometime also called total sleep time, refers to the
total night sleep minus the duration of night waking. Time in bed refers to a
period when a person is in bed.
In regard to objective methods, two sets of instruments, polysomnography
and actigraphy, are usually used. Polysomnography is often used in sleep
laboratories. Actigraphy is a portable device usually attached to participants’
wrists and arms to record their sleep behaviors. Parameters of objective methods
include sleep onset and offset time, sleep duration, true sleep time, frequency of
night waking, duration and frequency of night waking, and activity level during
20
sleep, which is similar to restlessness in the subjective method. Moreover, sleep
parameters in objective studies sometimes are categorized into REM sleep
parameters and non-REM sleep parameters. REM parameters include percentage
of REM sleep, and REM density. REM density refers to the density of eye
movements during REM sleep. Non-REM sleep includes percentage of stage 1,
stage 2, and SWS sleep, non-REM density, and stage 2 sleep spindles. Non-REM
density refers to the density of eye movements during non-REM sleep.

Functions of Sleep
For many years, sleep has been thought to have its influence on waking
behaviors. Accumulated data also provide some evidence of this influence.
Several perspectives of sleep functions in human waking behavior are discussed
in the literature, including energy conservation, physical restoration, and brain
thermoregulation (Maquet, 2001; Buysse, 2005). Evidence of the association
between sleep and learning and memory has also accrued as sophisticated
techniques such as functional magnetic imaging are developed. This association
with learning and memory involves brain plasticity during sleep. It is thought that
during sleep, memory is consolidated in the levels of molecular, neuron, brain
region, and behavior (Maquet et al., 2003).
Behaviorally, performances of sleep-dependent learning, also called
procedural sensory motor learning, such as finger-to-thumb opposition (Fischer et
al., 2002), finger tapping (Walker et al., 2002; Walker at al., 2003), target tracking
(Maquet et al., 2003), and visual texture discrimination (Gais et al., 2000),
improve during a period of repetitive practice and also enhance after a night of
21
sleep followed by a practice. Studies show that after a training session,
improvement of sleep-dependent learning reaches its plateau. Increasing practice
has no more effect on these performances. However, when a night’s sleep follows,
improvements occur and both quality and quantity of the performances increase.
Procedural learning, categorized as non-declarative learning, is a “how” learning,
such as learning an action, a habit, or a skill; procedural motor learning often
requires more practice and more motor repetition then declarative learning, which
is a “what” learning involving fact-based information and requiring less exposure
to the new information (Walker, 2005). Procedural learning also involves working
memory and executive functions (Rauchs et al., 2005). Participants who do not
sleep during the night after training perform worse than those with half-night
sleep. Participants with a full night of sleep perform the best. Moreover, explicit
sleep-dependent learning benefits more than implicit learning from the first night
of sleep (Robertson et al., 2004). Explicit learning is the learning in which
learners are intentionally aware of what they learn while implicit learning is the
learning in which learners have little awareness of learned new skills. Because all
of these existing studies on the effects of sleep on learning were done in adults,
no evidence shows that this memory consolidation of sleep-dependent learning
also can occur in children.
Generally, both in adults and children, the quality and quantity of sleep
correspond with changes in waking behavior (Harvey & Kennedy, 2002). Studies
on sleep deprivation, mainly in adults, and effects of sleep on waking behavior in
both children with special needs and typically developing children, indicate that
poor sleep quality and insufficient sleep negatively impact the ability to pay
22
attention (Chervin et al., 2002) and other aspects of cognitive, emotional, and
behavioral functioning (Dahl, 1996a), and also yield more frequent internalizing
and externalizing problem behaviors and poor performances (Limoges et al.,
2005; Patzold et al., 1998; Suzuki et al., 2005).
Paavonem et al. (2003) in a longitudinal study used parent and children
sleep questionnaires to investigate the influence of persistent and current sleep
disturbances on mental health behaviors in children aged 8 and 12. Results
showed that in both parent and child reports, numbers of children with sleep
problems decreased as children were older. Both previous and current sleep
disturbances were associated with anxiousness/depression, interpersonal skills,
attention, and thought problems observed by their school teachers. Suzuki et al.
(2005) investigated the influence of sleep-wake rhythms on copying triangular
figures in typically developing children with ages of 5 to 6 years. They used a
sleep questionnaire and diary to gather data on total sleep duration, sleep onset
time, and wake-up time and found that 34 of 222 typically developing children
had irregular sleep onset and wake-up time. Furthermore, 15 of the 34 children
with irregular sleep-wake rhythms had poor performance in copying triangular
figures. 23 of the other 188 children without irregular sleep-wake rhythms failed
to copy a triangle.
Sadeh et al. (2002) used actigraphy to measure sleep for a consecutive 5
days in 135 typical elementary children selected from three different grades,
second, fourth, and sixth to examine its association with neurobehavioral
functioning and behavior problems. They found that after controlling age, two
neurobehavioral measures, symbol-digit substitution (SDS) and continuous
23
performance test (CPT), are associated with sleep percent. Symbol-digit
substitution (SDS) is a test that requires participants to match a symbol and a
digit on a screen, based on 6 symbol-digit pairs, shown on the top of a screen.
The continuous performance test (CPT) is used for measuring sustained visual
attention. Participants are required to respond to a certain image as soon as
possible, presented on a screen. Sleep percent is the percentage of true sleep time
within total sleep duration. The researchers found that more fragmented sleep was
associated with poor performance on the SDS and more errors on the CPT. In
other words, fragmented sleep affected sustained visual attention and, when those
children did multiple choices, compromised executive functions. Both of these
two abilities are aspects of executive functions. The executive functions (EF) are
defined as a cognitive construct for goal-oriented and future-oriented behaviors
and includes “planning, inhibition of predominant responses, flexibility,
organized search, self-monitoring, and the use of working memory” (Ozonoff et
al., 2005). Furthermore, the Sadeh et al. (2002) study also showed that the second
grade children had more fragmented sleep than the fourth grade and sixth grade,
and their sustained visual attention and inhibition of responses were also poorer.
Several other studies (Dahl, 1996b; McCarthy & Waters, 1997; Pilcher &
Huffcutt, 1996) also support that insufficient sleep links with attention deficit and
executive functions.
That sleep is associated with emotion, cognition, and behavior is also
evidenced from the studies of children with special needs. Richdale et al. (2000)
recruited 52 children with intellectual disabilities (ID) including Down syndrome,
autism, fragile X syndrome, developmental delay, cerebral palsy, and other
24
genetic disorders to compare their sleep problems, behavioral problems and their
parents’ stress level to a control group with 25 typically developing children. All
of the parents filled out a sleep questionnaire, behavioral checklist, and stress
questionnaire. Results showed that sleep problems, behavioral problems, and
parents’ stress for children with ID were more severe than in the control group.
Moreover, the lower the IQ those children had, the more severe those problems
were and the more stressed their parents were. In these two groups, children with
sleep problems tended to have more behavioral problems, such as social-relating
problems, communication disturbance, anxiety, and disruptive behaviors.
Because of the relatively small sample size in this study, the association between
sleep problems and behavioral problems and parents’ stress could not be analyzed
in the control group. Although the Richdale et al. (2000) study did not separate
differently diagnosed children, there is evidence that children with different
neurodevelopmental disorders tend to have different patterns of sleep problems
(Hoban, 2000), and those different patterns may be associated with certain
behavioral traits in those children. For example, children with Down syndrome
tend to have Sleep Disordered Breathing Deficits (SDB) (Marcus et al., 1991).
Their SDB may be associated with their difficulties with cognitive functions,
especially visual perceptual skills such as visual orientation (Andreou et al.,
2002). Moreover, in children with pervasive developmental disorders, their main
sleep problems involve sleep onset and maintenance, correlated with their unique
social characteristics (Patzold et al., 1998).
Indeed, sleep is closely associated with waking behavior. Frequency of
internalizing and externalizing problem behaviors and performances of
25
neurobehavioral measures, copying triangular figures, and procedural motor
learning so far are evidenced to be associated with the quality and quantity of
sleep. Although more studies are still needed to deeply decipher these
associations and to discover other sleep functions, the possibility that sleep may
be closely related to clients’ abilities to engage in occupations is compelling.
Therefore it is important for occupational therapists to not only pay attention to
currently existing sleep studies, but also to study effects of sleep on occupation.

Section III: Sleep Patterns and Sleep Problems in People with ASD
This section depicts sleep patterns and sleep problems in people with ASD.
First, in order to understand sleep patterns and sleep problems in typically
developing children, development of sleep are given. Then sleep in children with
autism spectrum disorders is further described. Finally, studies about sleep
patterns and sleep problems in people with ASD are summarized in detail. In this
way, sleep as a problem in people with autism spectrum disorders is highlighted.

Sleep in Typically Developing Children
Sleep is essential for children. Typically developing young children spend
more time in sleeping than waking (Dahl, 1998). On average, full-term newborns
sleep for about 16 to 18 hours a day (Roffwarg et al., 1966), and 2 year-old
children spend about 13 hours a day sleeping (DeGangi, 2000). As their ages
increase, their sleep quantity decreases. Although sleep quantity varies due to
individual physiological differences and family schedules, on average, by the age
of 5 years, children sleep for about 10 to 12 hours a day (Sheldon, 2002).
26
Moreover, sleep patterns are very different with age during the first 5 years of life.
Around the age of 3 months, sleep states and sleep stages can be identified and a
sleep cycle is for about 50-60 minutes per cycle (Anders et al., 1995). A sleep
cycle refers to a period of rapid eye movement (REM) sleep and non-rapid eye
movement (NREM) sleep. A night of sleep contains repeated sleep cycles. REM
sleep and NREM sleep are the two main sleep states. In normal newborns, the
longest sleep period is about 2.5 to 4 hours a night (Adair & Bauchner, 1993),
while by the age of 6 months, the longest sleep period increases to about 6 hours
per night (Anders et al., 1995). By the age of 3 years, a sleep cycle is stable for
approximately 60 minutes while by the age of 5 years, a sleep cycle increases to
90 minutes (Sheldon, 2002). In children aged 5 years, both the duration of a sleep
cycle and the proportions of sleep states are similar to those in adults (Roffwarg
et al., 1966).
Sleep problems are the problems often asked about by parents. A sleep
problem is a sleep pattern that interferes with sleep architecture and interrupts
parents’ sleep (Adair & Bauchner, 1993). Sleep architecture refers to the
progression of the entire night of sleep (Davis et al., 2004a). Sleep problems
consist of two main types: dyssomnias and parasomnias. Dyssomnias refer to
difficulties in initiating and maintaining sleep at night and problems with
excessive daytime sleepiness (Mindell, 1999). Parasomnias refer to undesirable
automatic motor phenomena during sleep, such as sleepwalking and sleep terrors
(Anstead, 2000). Generally, approximately 20% to 30% of typically developing
children younger than 5 years old have some sleep problems (Dahl, 1998).
However, this figure in children with autism spectrum disorders is much higher.
27
Sleep in Children with Autism Spectrum Disorders
Sleep in children with autism spectrum disorders (ASD) is often seen as an
issue. Compared to parents of typically developing children, more parents of
children with autism spectrum disorders report their children having sleep
problems and the severity of sleep problems is greater (Honomichl et al., 2002;
Patzold et al., 1998). Moreover, by the age of 3 months in normal newborns, the
EEG features of their sleep stages and states are already differentiable. However,
according to the Diomedi et al. (1999) study, people aged 12 to 24 years with
autism and intellectual disabilities still have a greater percentage of
undifferentiated sleep states and stages.
In addition to required symptoms for the diagnoses of autism spectrum
disorders, sleep problems are frequently seen in this group of children. Sleep
problems may not only result from family issues, but also from neurological,
psychological, and physical problems in children (Rosen, 1997). Sleep problems
also increase rearing stress and parents’ anxiety (Honomichl et al., 2002) and
disrupt caregivers’ sleep (Johnson, 1996). Moreover, recent studies (Hoffman et
al., 2005; Schreck et al., 2004) show that sleep problems might be predictors of
autism’s intensified symptoms.
In the autism literature, problem sleep prevalence estimates of 56%, 65%,
and 68% have been reported in children with autism spectrum disorders
(Richdale, 1999). A prevalence ranging from 44% to 83% has also been reported
(Patzold et al., 1998; Richdale & Prior, 1995). Children with autism spectrum
disorders younger than 8 years old are the most likely to have severe sleep
problems (Richdale, 1999). Sleep problems in this group of children include
28
symptoms both from dyssomnias and parasomnias (Couturier et al., 2005;
Schreck & Mulick, 2000). Difficulties in initiating and maintaining sleep,
shortened night sleep, and restlessness during sleep are often recorded (Richdale,
1999). Apparently, sleep issues are much more severe in children with autism
spectrum disorders. Moreover, studies in the sleep literature have shown that
sleep problems in people with autism spectrum disorders may be associated with
both internalizing and externalizing problem behaviors (Limoges et al., 2005;
Patzold et al., 1998), poor social skills, impaired communication, persistence on
sameness, and poor adaptation (Hoffman et al., 2005; Elia et al., 2000; Patzold et
al., 1998; Richdale et al., 2000; Schreck et al., 2004; Segawa et al., 1992).

Sleep Patterns and Behavioral Problems in People with ASD
In the studies which employed diaries or questionnaires, sleep problems in
people with autism spectrum disorders (ASD) often include difficult sleep onset
and maintenance, irregular sleep-wake schedule, frequent night waking, longer
duration of night waking, longer sleep latency, shortened night sleep, early
morning awakening, and poor sleep hygiene (Richdale, 1999). Irregular
sleep-wake schedule refers to frequent transitions between light sleep stage and
deep sleep stages. Sleep hygiene refers to sleep routines or habits that initiate
sleep onset and facilitate sleep maintenance (Davis et al., 2004b).
Patzold et al. (1998) investigated sleep characteristics in children with autism
and Asperger’s disorder. They recruited two groups of children, the Pervasive
Developmental Disorder (PDD) group and the control group, matched on age and
gender. The PDD group contained 38 children with autism and Asperger’s
29
syndrome. Their age range was from 44 to 152 months, and average age was 93.5
months (SD=31.5). The control group had 36 children with other developmental
disabilities. Their age range was from 63 to 171 months, and average age was
101.2 months (SD=31.0). All of the children were also grouped into high IQ
(IQ>55) group and low IQ (IQ<=55) group, and younger group (<=84 months)
and older group (>84 months). A sleep diary was used to collect 2-week sleep
behaviors, and two behavior checklists, the Child Behavior Checklist (Achenbach,
1991) and the Developmental Behavior Checklist (Einfeld & Tonge, 1994), were
used to gather problem waking behaviors.
The results of group differences in sleep showed that, first of all, more
children with PDD had current and past sleep problems than the control group.
Second, children with PDD tended to be less ready to go to bed. They tended to
have different bedtime routines and required their parents by their sides when in
bed. Third, children with PDD took a longer time in bed to fall asleep and a
longer duration when waking at night. When waking, children with PDD tended
to have disruptive behaviors, such as banging walls and playing around,
compared to the control group, who had behaviors like going to their parents’ bed
or to the bathroom. Moreover, children with a low IQ and younger children from
both groups woke more frequently. In addition, average total night
sleep in children with PDD was half an hour less, compared with the control
group. Finally, no difference in the sleep quality between these two groups was
found.
The results of group differences in daytime behaviors showed that although
there were no significant differences between groups in daytime nap and
30
calmness, children with autism tended to be more energetic and have more
waking behavioral problems, such as disruptive behaviors, self-absorbed
behaviors, and communication disturbances.
Beyond these group differences detected in this study (Patzold et al., 1998),
correlation coefficients were used to analyze associations between sleep
characteristics from the sleep diary and daytime behaviors from the behavior
checklists. In the PDD group, sleep characteristics, such as past and current
reported sleep problems, night waking, and poor sleep quality were associated
with waking problem behaviors. In the control group, although restless sleep and
night waking were associated with daytime behavioral problems, shorter night
sleep was associated with autistic-related behaviors, such as social difficulties.
Patzold et al. (1998) further found that IQ was not related to overall sleep
disturbance in either the PDD group or the control group. Although older children
without PDD tended to have fewer sleep difficulties, older children with PDD
still had difficulties.
Schreck and Mulick (2000) used the Behavior Evaluation of Disorders of
Sleep to investigate sleep characteristics in 5 age-matched groups of children,
children with autism, children with PDD, children with mental retardation (MR),
children attending special programs without MR, and typically developing
children. The Behavior Evaluation of Disorders of Sleep (BEDS) is a sleep
questionnaire developed by Schreck (1997/1998), designed to investigate sleep
characteristics in children aged from 5 to 12 years old. The BEDS contains
questions about two main types of sleep problems: dyssomnia and parasomnia.
Those questions are further sorted into 5 factors: expressive sleep disturbances,
31
sensitivity to the environment, disoriented awaking, sleep facilitators, and
Apnea/Bruxism. The Gilliam Autism Rating Scale (GARS) was used in this study.
The GARS is a rating scale to diagnose autism. A GARS autism quotient (AQ)
score greater than or equal to 80 indicates a greater possibility of autism (Gilliam,
1995). Children in the autism group were identified when they had a GARS
autism quotient score G 80, and their parents reported they had autism. Children
in the PDD group were identified as having GARS scores matching the criterion
of autism, but in the absence of parental report of autism. A total of 169
questionnaires were valid. Because no differences were found between children
with autism and PDD in sleep parameters, data from these two groups of children
were combined for further analyses. Moreover, no differences in the amount of
total hours of night sleep, hours slept in the last 24 hours, and number of naps
were found among these 4 groups. However, differences appeared in that parents
of children with autism and PDD tended to report more sleep problems in their
children.
For the results related to the 5 factors, children with autism had the highest
scores on all of the 5 factors. Schreck and Mulick (2000) concluded that children
with autism showed more nightmare type disturbance and environmental
disturbance, had more need for sleep facilitators and greater frequency of sleep
breathing problems, and had more severe disoriented awakening.
Polimeni et al. (2005) also used the BEDS to investigate three groups of
children: children with autism, children with Asperger’s syndrome, and typically
developing children. Results showed no differences in the amount of total hours
of night sleep, hours slept in the last 24 hours, and number of naps among these
32
three groups. However, children with Asperger’s syndrome tended to have more
disoriented arousal than the other 2 groups.
The greatest discrepancy between the findings of the Schreck and Mulick
(2000) study, the Polimeni et al. (2005) study, and the Patzold et al. (1998) study
is on the amount of total sleep. Patzold et al. found that average total sleep time
was half an hour less in children with PDD than that in the control group, while
Schreck and Mulick (2000) and Polimeni et al. (2005) did not find any
differences in the amont of total sleep among participants. Schreck and Mulick
explained that their finding of a difference on the amount of total sleep might
result from the ages of their participants, because compared with infants and
toddlers, school-age children, have a relatively stable average total sleep time.
Moreover, because both expressive sleep disturbances and sleep breathing
disorders involve movements, the authors concluded that problems with these
two factors in children with autism and PDD might imply a possible impairment
in the motor area of the CNS in this group of children.
Although Patzold et al. (1998) concluded that IQ was not associated with
overall sleep characteristics in children with autism and Asperger’s syndrome,
both they and Williams et al. (2004) found that IQ was associated with night
waking. Williams et al. (2004) found that in 210 children with autism in the age
range from 4 to over 11 years old, age was not associated with overall sleep
problems. Moreover, they listed the most frequent sleep problems in this group as
sleep onset problem, restless sleep, night waking, and sleeping in another’s bed.
Schreck et al. (2004) further analyzed the data from their previous study
(Schreck & Mulick, 2000) to examine relationships between specific sleep
33
problems and symptoms of autism. Fifty five children whose GARS AQ scores
were higher than or equal to 80, and whose parents reported they had autism were
included in this study. The authors first calculated Pearson correlation coefficients
to analyze the associations between the factors and items on the BEDS and the
domains of the GARS. The factors assessed on the BEDS include expressive
awakening, sensitivity to the environment, disoriented awaking, and apnea. The
items on the BEDS are sleep hours per night and hours of naps. The domains on
the GARS include stereotyped behavior, communication, social interaction,
developmental disturbances, and an overall autism quotient (AQ). Results were
that hours slept per night was significantly correlated with stereotyped behavior,
social interaction, and overall autism quotient. Expressive awakening was
significantly correlated with stereotyped behavior, communication, social
interaction, and developmental disturbances. Moreover, by using stepwise
multiple linear regression analyses, the authors found that sensitivity to the
environment along with expressive awakening predicted scores on the
communication domain on the GARS. Sensitivity to the environment also
predicted developmental disturbances. Hours slept per night along with
expressive awakening predicted stereotyped behavior. Hours slept per night
predicted social interaction and overall autism quotient. The authors concluded
that although whether sleep problems cause, maintain, or exacerbate daytime
behavioral difficulties in children with autism was difficult to be answered, sleep
problems were directly connected with the symptoms of autism.
Hoffman et al. (2005) also investigated the relationships between specific
sleep problems and autistic symptoms. The authors used the GARS to measure
34
symptoms of autism and the Child’s Sleep Habits Questionnaire (CSHQ) to
measure specific sleep problems. The CSHQ is a sleep questionnaire designed to
measure sleep behaviors and habits of children aged from 4 to 12 years old
(Owens et al., 2000). In addition to a total score, CSHQ contains 8 subscales:
bedtime resistance, sleep onset delay, sleep duration, sleep anxiety, night waking,
parasomnias, sleep-disoriented breathing, and daytime sleepiness. A total of 80
children were sampled. Pearson correlation and stepwise multiple linear
regression were used to test associations and predictions. Results from Pearson
correlation coefficient analysis showed that 3 of the CSHQ 8 sub scores -
parasomnias, sleep-disordered breathing, and daytime sleepiness - were all
significantly associated with stereotyped behavior, social interaction, and autism
quotient. Sleep duration was significantly associated with the social interaction,
developmental disturbances, and autism quotient. Night waking was significantly
associated with developmental disturbances and autism quotient. Besides those
associations, results from stepwise testing showed that sleep-disordered breathing
predicted stereotyped behavior and social interaction. Parasomnias along with
sleep duration predicted developmental disturbances. Sleep-disordered breathing
along with parasomnias predicted autism quotient. At the end, the author
discussed that although in a previous study sleep duration was found to be the
primary predictor of stereotyped behavior, social interaction, and overall level of
autism, in the present study sleep-disordered breathing and parasomnias were
found to be the primary predictors of symptoms of autism.
Couturier et al. (2005) also used the CHSQ to conduct a study to
investigate the prevalence, severity, and pattern of sleep problems in children
35
with PDD but without intellectual disabilities. They sampled 23 children with
autism with a mean age of 9.4 years (SD=2.0) and paired these children with
autism to 23 typically developing children of their age, gender, and postal code.
These typically developing children had a mean age of 9.5 years (SD=2.0).
Results showed that 78% of children with PDD, but without intellectual
disabilities had sleep disturbances that parents of children with PDD rated more
severe sleep problems than parents of typically developing children, and that
significant differences between these two groups of children were shown on 4
subscales: sleep onset delay, sleep duration, sleep anxiety, and parasomnias. In
other words, children with PDD had delayed sleep onset, decreased sleep
duration, increased sleep anxiety, and more parasomnias.
Comparing these findings with those in previous studies, the results of
delayed sleep onset and decreased sleep duration in children with PDD are the
same as those obtained from the Patzold et al. study. The results of increased
parasomnias and more severity of sleep problems in children with PDD are in
agreement with those in the Shreck and Mulick (2000) study.
Cotton and Richdale (2006) used a brief parental report of sleep
disturbances in children with intellectual disabilities. Participants were those who
had participated in previous three sleep studies: Patzold et al., (1998), Richadel et
al., (1999), and Richdale et al., (2000) studies. Children with autism, Down
syndrome, Prader-Willi syndrome, non-specific intellectual disabilities, and
controls aged 2 to 18 years were recruited. Thirty seven children with autism
were sampled. Demographic and sleep questionnaires were used. In the sleep
questionnaire, yes-no questions were used to ask about the presence of current
36
and past sleep problems, and a 100-mm visual analogue scale was used to
examine the severity of sleep behavior problems. Despite no significant group
differences in the severity ratings, the group of children with autism spectrum
disorders showed higher presence of sleep problems which frequently included
settling down difficulties, co-sleeping, and sleep maintenance problems.
Cotton and Richdale’s findings are in agreement with those in Patzold et al.
(1998), Schreck and Mulick (2000), Polimeni et al. (2005), and Couturier et al.
(2005). All of previous investigators found that parents of children with autism
spectrum disorders report more presence of sleep problems. Specifically, the
parents of these children perceived that their children demonstrate bedtime
resistance, and have settling down difficulties and sleep maintenance difficulties.
In summary, although findings on differences in amount of total sleep in
children with PDD and typical developing children are not yet conclusive, sleep
patterns, the severity of sleep problems, and the relationships between sleep
problems and daytime problem behaviors in children with autism spectrum
disorders are conclusive in above studies employing diaries or questionnaires.
Moreover, younger people with autism spectrum disorders have more frequency
of night waking. People with autism spectrum disorders with lower IQs presented
also have more frequency of night waking. Finally, the evidence presented also
shows that sleep problems in children with autism are not only associated with
daytime problem behavior, but are also significantly related to autistic symptoms.
In the studies that used polysomnography or actigraphy to investigate sleep
problems in people with autism spectrum disorders, findings are often
inconclusive. Godbout et al. (2000) recorded sleep parameters during two
37
consecutive nights in a sleep laboratory of 8 participants with Asperger’s
syndrome, ranging in age 7 to 53 years old. The comparison group consisted of 8
participants without Asperger’s syndrome, matched on age and gender. The
parameters included sleep onset, total sleep time, the first, second, and third thirds
periods of the total sleep time, respiratory flow, periodic leg movements in sleep
(PLMS), stage 2 sleep spindles, and REM density. Results showed that people
with Asperger’s syndrome had shorter periods of the first third of night sleep and
second third of night sleep. Moreover, although their percentage of REM sleep
did not different from that in the control group, the participants with Asperger’s
syndrome had more frequency of shifts from waking to REM sleep and stage 2 to
REM sleep. They also had lower density of sleep spindles. The authors concluded
that the shorter time of two thirds of the night sleep indicated that people with
Asperger’s syndrome have difficulty in initiating and maintaining sleep.
Frequently shifting from waking to REM and stage 2 to REM might indicate the
fragmentation of REM sleep in people with Asperger’s syndrome, which might
also be related to their daytime cognitive difficulties. Lower density of stage 2
sleep spindles might indicate selective attention atypicalities in people with
Asperger’s syndrome.
In order to compare sleep parameters in different populations, Diomedi et
al. (1999) recruited three groups of people to be recorded in a sleep laboratory for
two consecutive days. One group consisted of 10 people with autism and mental
retardation whose ages ranged from 12 to 24 years old. The other two comparison
groups respectively consisted of 8 subjects with Down syndrome and 8 normal
participants. The Down syndrome group was matched with the autistic group on
38
chronological age, and mental age, as well as gender. The normal group was
matched with the autistic group on chronological age and gender. Parameters
included percentages of stage 1, stage 2, SWS sleep, REM sleep and
undifferentiated sleep, number of REM cycles and REM activity, REM density,
number and percentage of night awakening, sleep efficiency index, R index, tonic
inhibition index, and phasic inhibition index. Undifferentiated sleep referred to
the sleep that presents both REM and non REM sleep elements in a 30 second
epoch. Number of REM cycles refers to the number of REM periods following
with at least 15 minutes non-REM sleep. Number of REM activity is the number
of rapid eye movements. The sleep efficiency index refers to the index of true
sleep time divided by total time in bed. True sleep time is the time from sleep
onset to sleep offset minus the duration of night waking. The R index refers to the
ratio of high frequency REM to low frequency REM. The Tonic inhibition index
is the ratio between the number of chin muscle activities (twitches) for less then
0.5s and that for more than 2.0s. The Phasic inhibition index is the ratio of the
number of chin muscle activities (twitches) for more than 2.0s and total number
of muscle activities. Results of the comparison between the autistic and control
groups showed that the autistic group had a lower percentage of REM sleep, a
higher percentage of night waking, greater frequency of night waking, more
undifferentiated sleep, lower sleep efficiency, and a higher phasic inhibition
index.
However, the result of lower REM percentage in the Diomedi et al. study
was not in agreement with that in other studies (Elia et al., 1993; Aihara &
Hashimoto, 1986), which showed no significant difference in this parameter
39
between subjects with autism and normal subjects. Diomedi et al. further
concluded that this lower REM percentage might be another sleep characteristic
in subjects with autism and mental retardation. Although REM sleep was
evidenced to be related to IQ (Espie & Tweedie, 1991; Espie et al., 1998; Stores,
1992), in this study, in contrast to people with Down syndrome, there was no
association of IQ in the autistic group with their REM percentage. The authors
pointed out a possible reason that poor IQ performance might not only result
from low intellectual ability, but also from other dysfunctions, such as poor
attentiveness. In addition, the higher percentage of undifferentiated sleep was
similar to that in newborns. This might indicate that people with autism have
immature EEG activity in sleep. Finally, the higher phasic inhibition index in
people with autism was also found in a study conducted by Elia et al. (1993) and
might indicate poor cortical inhibition.
Beyond using polysomnography, Hering et al. (1999) empolyed both
actigraphy and a self-developed questionnaire to collect data on sleep parameters
in 18 autistic children aged 3 to 12 years and 8 controls. The sleep parameters
were sleep onset and offset times, sleep duration, early night arousals, multiple
night arousals, sleep efficiency, and activity level. Night arousal refers to sleep
termination during the night. Results indicated that only sleep offset time showed
a significant difference between children with autism and controls in both
subjective and objective methods, although questionnaire data also showed a
difference in night arousals.
The original purpose of the Hering et al. study was to apply actigraphy to
outweigh the disadvantage of using questionnaires. However, the findings from
40
the actigraphy method did not correspond to those from the questionnaire method
as well as from previous subjective and objective studies. Therefore, the authors
concluded that two possible reasons might have resulted in the ambiguous
findings. One might be that younger participants in this study, who didn’t
complete the measure due to intolerance to the contact on their wrists or arms
from actigraphic devices, might have more sleep disturbances, which were
compatible with previous findings. The other might be that the phenomenon of
sleep problems in children with autism spectrum disorders involved neurological
damage resulting in different patterns of REM sleep which was not detectable
with actigraphy, but was with polysomnography.
The Elia et al. (2000) employed polysomnography to investigate different
sleep patterns and the Psychoeducational Profile (PEP-R: Schopler et al., 1990)
and Childhood Autism Rating Scale (CARS: Schopler et al., 1980) to study the
associations between sleep parameters and behavioral variables. They sampled
three groups of people: 17 male participants with autism in the age range from 5
years 7 months to 16 years 8 months, 7 subjects with fragile X syndrome and
mental retardation, and 5 age-matched typically developing participants. Sleep
parameters, measured in a night, included percentages of each sleep stage and
wakefulness after sleep onset, REM density, sleep efficiency index, number of
stage shifts, number of awakenings, sleep onset latency, first REM sleep latency,
total sleep time, sleep period time, and time in bed. Submentalis muscle twitches
were measured during each sleep stage. One twitch was measured with duration
of less than 1s and amplitude of three times base-line muscular tone. Results
showed that participants with autism had less time in bed, less sleep period time,
41
and less total sleep time. Other differences were in the muscle contractions in
stage 2 and REM sleep. Participants with autism had more frequent muscular
twitches.
For the results of the associations between sleep parameters and behavior
variables, the passing score in the PEP-R perception was negatively associated
with sleep latency, number of stage shifts, first REM sleep latency, and
percentage of night waking, but was positively correlated to the parameter of time
in bed. Moreover, the passing score of PEP-R eye hand coordination was
negatively associated with stage shifts, first REM latency, and percentage of night
waking, but positively with sleep period time. That is, people performing better
eye hand coordination in the PEP-R have fewer stage shifts, shortened first REM
latency and smaller percentage of night waking, but longer sleep period time.
Furthermore, the passing score of CARS visual response was negatively
associated with sleep period time but positively with percentage of night waking.
In other words, people with severe problems in visual response indicated with
higher scores in the CARS have shorter sleep period time but greater percentage
of night waking. In addition, CARS non-verbal communication was negatively
associated with total sleep time. That is, people with severe problems in
non-verbal communication have shorter total sleep time. Finally, CARS activity
level was negatively associated with the density of eye movements in REM sleep.
That is, people with higher activity level have less density of eye movements in
REM sleep.
The authors summarized their findings of sleep patterns as indicating that
children with autism experience shorter time in bed, shorter sleep period time,
42
and shorter total sleep time. These findings are consistent with other studies
(Ornitz et al., 1969; Tanguay et al., 1976). Moreover, these findings also indicate
brainstem dysfunction in modulating sleep. They further pointed out that the
increased muscle twitches in participants with autism might be related to
inhibitory dysfunction, which is related to dopaminergic system.
Regarding the discovered associations between sleep parameters and
behavioral parameters, the authors concluded that participants with autism who
showed more severe sleep problems also demonstrated lower functions of
perception, eye-hand coordination, and non-verbal communication.
Limoges et al. (2005) used polysomnography as well as a sleep
questionnaire to investigate sleep architecture in 27 high functioning adults with
autism spectrum disorders (ASD) without self-reported sleep disturbance and 78
normal participants matched with chronological age and gender. The
experimental group contained 21 high functioning adults with autism and 6
people with Asperger’s syndrome with the age range 16 years to 27 years. Sleep
parameters in 2 consecutive nights were recorded. Psychological functioning
from a self-reported adaptive behavior scale, an anxiety scale, and a depression
scale were also collected. Cortisol levels from all participants’ saliva were taken.
Sleep parameters on the questionnaire were grouped into three categories:
sleep initiation and continuity, sleep-wake schedule, and sleep qualitative
perception. The sleep initiation and continuity included sleep onset latency,
frequency and duration of night waking, total sleep time, and sleep efficiency.
The sleep-wake schedule included weekday bedtime and rise time, weekend
bedtime and rise time, time in bed and naps. The qualitative perception included
43
feeling of restfulness and sleep satisfaction. Results are that no difference in sleep
qualitative perception was found between the experimental group and control
group. However, differences were found in sleep initiation and continuity and
sleep-wake schedule. Participants with ASD had longer sleep onset latency, with
about three days in which they were in bed for over 30 minutes before falling into
sleep. Normal participants had about one day a week in bed over 30 minutes
before sleep. Greater frequency of night waking, longer time during night waking,
and poor sleep efficiency were found. Regarding sleep-wake schedule, subjects
with ASD tended to go to bed earlier both on the weekdays and weekend. Rising
earlier was only found on the weekdays, and on the weekend they tended to
spend more time in bed.
Sleep parameters obtained from polysomnography were sleep initiation and
continuity, non-REM sleep parameters, EEG phasic events, REM sleep
parameters, electro-oculogram (EOG) phasic events, and periodic limb
movements during sleep (PLMS). Parameters in the sleep initiation and
continuity were the same as those in the parameters obtained from the
questionnaire. The Non-REM sleep parameters included percentages of each
sleep stage, stage (2+3+4), and stage (3+4). The EEG phasic events mainly
measured the stage 2 sleep spindles. The REM sleep parameters refer to REM
sleep latency, percentage of REM sleep, and REM cycle. EOG phasic events
included REM density and non-REM density. The findings of the sleep initiation
and continuity from the objective parameters were the same as those from
subjective parameters. Results are that no differences were found in the PLMS
and REM sleep parameters. In the non-REM sleep parameters, percentages of
44
Stage (2+3+4), and stage (3+4) were significantly lower in participants with ASD.
In the EEG phasic events, stage 2 sleep spindles were less in this population.
REM density was also lower.
Regarding psychological functioning and cortisol level, although no
difference in cortisol level was found, behaviorally higher trait anxiety and more
internalizing adaptive behaviors, such as withdrawal, social problems, somatic
complaints, and thought problems, were found in participants with ASD.
No differences in both psychological functioning and sleep measures were
found in two subgroups: participants with high function autism and Asperger’s
syndrome. Regarding the associations between psychological functions and sleep
parameters, in participants with autism spectrum disorders, total sleep time was
negatively associated with social and communication items in ADI-R, and
percentage of REM sleep was positively associated with internalizing adaptive
behaviors. In participants with Asperger’s syndrome, negative associations were
found between REM sleep latency and depression and internalizing adaptive
behaviors. However, in participants with high functioning autism, no statistically
significant association was found between sleep parameters and psychological
functioning.
These authors concluded that first, even though participants in ASD did not
indicate they had sleep disturbance, their sleep patterns were different than
normal subjects. Second, even though no differences were found between
participants with ASD and normal subjects in total sleep time, this sleep
parameter was found to be negatively associated with social skills and
communication, which were symptoms of autism. This association was also
45
confirmed by several other studies (Patzold et al., 1998; Elia et al., 2000;
Richdale et al., 2000). Because the association between stage 2 sleep spindles and
sleep-dependent sensory motor learning, also called procedural motor learning,
was found in previous studies (Smith & MacNeill, 1994; Narder & Smith, 2003),
and people with ASD had poor sleep-dependent sensory motor learning,
compared to people without ASD (Mostofsky et al., 2000), the authors concluded
that their findings of reduced stage 2 sleep spindles might indicate their
participants with ASD had poor procedural motor learning. The lower density of
REM sleep found in participants with ASD might indicate this group’s different
cortical organization because of the possible association between cortical
organization and density of REM sleep (Ioannides et al., 2004).
Overall, although not all of the results of the sleep parameters from studies
employed polysomnography or actigraphy are consistent, the studies presented
point to, first, that people with autism spectrum disorders have different sleep
patterns, and second; these patterns mainly involve difficulties in sleep initiation
and maintenance.
In order to more clearly present the findings from all of the studies
presented, which employed both subjective and objective methods measuring
sleep patterns as well as associations between sleep problems and waking
behaviors in people with autism spectrum disorders, tables 1, 2, 3, and 4 are
presented. Subjective method refers to that the methodology studies used
involved diaries and questionnaires to collect data on subjective measures.
Objective method, on the other hand, refers to the methodology used involved
polysomnography and actigraphy to have data on objective measures. Tables 1
46
and 2 depict significant differences of sleep parameters in subjects with ASD
compared to typically developing subjects on subjective and objective measures.
Tables 3 and 4 organize the associations between sleep problems and waking
behaviors in subjects with ASD on subjective and objective measures.
Children with autism spectrum disorders are one of the primary populations
that pediatric occupational therapists serve. Problem sleep in this particular
population appears to be an important factor affecting their daytime behavior and
future disturbing their engagement of occupation. When pediatric occupational
therapists are concerned with children’s daily functions, sleep should be
considered.
47
Table 1. Significant differences of sleep parameters in subjects with ASD on subjective measures, compared to typically developing subjects
Differences Studies
Patzold et al. Limoges et al. Couturier et al. Schreck & Mulick Polimeni et al. Cotton & Richdale
Participants
Age range (years) 3.6-12.6 16-27 5-12 5-12 2-17 2-18
N 38 27 23 55 105 27
Sleep parameters:
Current sleep problems (%) Greater X X
Current severity rating Higher X
Past sleep problems (%) More X X
Past severity rating Higher X
Readiness for sleep at bed Less readiness X X
Behavior prior to bed No differences NS
Bedtime resistance More resistance X X
Light-off time (time) Later X
Sleep onset time Later X
Sleep latency (SL) (min) Longer X X
SL>30 or 20 min (nights/week) More X X
Night waking frequency More NS X X X
Night waking duration Longer X X X
Bedtime (weekdays) (hour) Earlier X
Rise time (weekdays) Earlier X
Bedtime (weekend) (hour) Earlier X
Time in bed (weekend) (h) Later X
48
Table 1. (Continued)
Differences Studies
Patzold et al. Limoges et al. Couturier et al. Schreck & Mulick Polimeni et al.
Sleep parameters
Total night sleep (min) Less X NS
Sleep duration (night + day) Less X
Daytime sleepiness No differences NS NS
Sleep efficiency (%) Less X
Sleep anxiety More anxiety X
Restlessness No differences NS
Expressive sleep disorders More severe X X
Sensitivity to environment More sensitive X X
Disoriented Awakening More disoriented X X
Sleep facilitator More needed X X
Apnea/ Bruxism More NS X X
Note. From “An investigation into sleep characteristics of children with autism and Asperger’s disorder,” by L. M. Patzold, A. L. Richdale, and B.
J.Tonge, 1998, Journal of Pediatrics and Child Health, 34, 528-533. “Atypical sleep architecture and the autism phenotype,” by E. Limoges, L. Mottron,
C. Bolduc, C. Berthiaume, and R. Godbout, 2005, Brain, 128, 1049-1061. “Parental perception of sleep problems in children of normal intelligence with
pervasive developmental disorders: Prevalence, severity, and pattern,” by J. L. Couturier, K. N. Speechley, M. Steele, R. Norman, B. Stringer, and R.
Nicolson, 2005, Journal of the American Academy of Child & Adolescent Psychiatry, 44, 815-822. “Parental report of sleep problems in children with
autism,” by K. A. Schreck, and J. A. Mulick, 2000, Journal of Autism and Developmental Disorders, 30, 127-135. “A survey of sleep problems in autism,
Asperger’s disorder and typically developing children,” by M. A. Polimeni, A. L. Richdale, and A. J. P. Francis, 2005, Journal of Intellectual Disability
Research, 49, 260-268. “Brief report: parental descriptions of sleep problems in children with autism, Down syndrome, and Prade-Willi syndrome.” by S.
Cotton and A. Richdale 2006, Research in Developmental Disabilities, 27, 151-161.
X = significant difference between control and experiment groups. NS = non significant.
49
Table 2. Significant differences of sleep parameters in subjects with ASD on objective measures, compared to typically developing subjects
Differences Studies
Godbout et al. Diomedi et a. Elia et al. Limoges et al. Hering et al.
Participants
Age range (years) 7-53 12-24 5.7-16.8 16-27 3-12
N 8 10 13 16 18
Sleep parameters:
Time in bed (min) Shorter X
Sleep period time (min) Shorter X
Total sleep time (min) Shorter NS X NS
Sleep offset time (hour) earlier X
Sleep time 1/3 (min) Less X
Sleep time 2/3 (min) Less X
Sleep latency (min) Longer NS NS X
Night waking (no.) More X NS X
Duration of night waking (min) Longer X
Density during REM Less NS NS X
Stage shifts (no.) NS
Waking to stage 1 More X
Waking to REM sleep More X
Stage 2 to REM sleep Less X
Non-REM sleep
Stage (2+3+4) % Less X
Stage (3+4) % Less NS NS X
50
Table 2. (Continued)
Differences Studies
Godbout et al. Diomedi et a. Elia et al. Limoges et al.
Sleep Parameters
Non-REM sleep
Stage 2 sleep spindles Less X X
REM % Less NS X NS NS
US% More X
Wake % More X NS X
Sleep efficiency Less NS X NS X
Muscle twitches in REM More X X
Muscle twitches in Stage2 More X
Note. From “A laboratory study of sleep in Asperger’s syndrome,” by R. Godbout, C. Bergeron, E. Limoges, E. Stip, and L. Mottron, 2000, Neuroreport,
11, 127-130. “Sleep abnormalities in mentally retarded autistic subjects: Down’s syndrome with mental retardation and normal subjects,” by M. Diomedi,
P. Curatolo, A. Scalise, F. Placidi, F. Caretto, and G. L. Gigli, 1999, Brain & Development, 21, 548-553. “Sleep in subjects with autism disorder: A
neurophysiological and psychological study” by M. Elia, R. Ferri, S. A. Musumeci, S. D. Gracco, M. Bottitta, C. Scuderi, et al.,2000, Development of
Brain Dysfunction, 22, 88-92. “Atypical sleep architecture and the autism phenotype,” by E. Limoges, L. Mottron, C. Bolduc, Berthiaume, and R.
Godbout, 2005, Brain, 128, 1049-1061. “Sleep patterns in autistic children,” by E. Hering, R. Epstein, S. Elroy, D. R. Iancu, and N. Zelnik, 1999,
Journal of Autism and Developmental Disorders, 29, 143-147.
X = significant difference between control and experiment groups. NS = non significant. Sleep time 1/3 = the first third period of the total sleep time.
Sleep time 2/3 = the second third period of the total sleep time. US% = percentage of undifferentiated sleep.
51
Table 3. Associations between sleep problems and waking behaviors in subjects with ASD on subjective measures
Instruments Instruments Studies
Sleep parameters +, - Daytime behaviors Patzold et al. Limoges et al. Hoffman et al. Schreck et al.
Diary Diary
Current sleep problems + Problem daytime behavior X
Past sleep problems + X
Night waking + X
Sleep quality - X
DBC
Current sleep problems + Total problems behavior X
Past sleep problems + X
Diary CBC
Current sleep problems + Total problem behavior X
Past sleep problems + X
Past severity rating + X
Diary ADI-R
Total sleep time - Social dimension X
- Communication X
CSHQ GARS
Sleep duration + Social interaction X
+ Developmental disturbances X
+ Autism quotient X
52
Table 3. (Continued)
Instruments Instruments Studies
Sleep parameters +, - Daytime behaviors Patzold et al. Limoges et al. Hoffman et al. Schreck et al.
CSHQ GARS
Night waking + Developmental disturbances X
+ Autism quotient X
Parasomnias + Stereotyped behavior X
+ Social interaction X
+ Developmental disturbances X
+ Autism quotient X
SDB + Stereotyped behavior X
+ Social interaction X
+ Autism quotient X
Daytime sleepiness + Stereotyped behavior X
+ Social interaction X
+ Autism quotient X
Total score + Stereotyped behavior X
+ Social interaction X
Total score + Developmental disturbances X
+ Autism quotient X
53
Table 3. (Continued)
Instruments Instruments Studies
Sleep parameters +, - Daytime behaviors Patzold et al. Limoges et al. Hoffman et al. Schreck et al.
BEDS GARS
Hours slept per night + Stereotyped behavior X
Expressive awakening + Stereotyped behavior X
+ Communication X
+ Social interaction X
Environmental factor + Social interaction X
+ Developmental disturbances X
Note. From “Sleep problems and sympotamology in children with autism,” by C. D.Hoffman, D. P. Sweeney, J.E. Gilliam, D. D., Apodaca, M. C.
Lopez-Wagner, and M. M. Castillo, 2004, Focus on Autism and Other Developmental Disabilities, 20, 194-200. “Sleep problems as possible predictors of
intensified symptoms of autism,” by K. A. Schreck, J. A. Mulick, and A. F. Smith, 2004, Research in Developmental Disabilities, 25, 57-66. “Atypical
sleep architecture and the autism phenotype,” by E. Limoges, L. Mottron, C. Bolduc, Berthiaume, and R. Godbout, 2005, Brain, 128, 1049-1061. “An
investigation into sleep characteristics of children with autism and Asperger’s disorder,” by L. M. Patzold, A. L. Richdale, and B. J.Tonge 1998, Journal
of Pediatrics and Child Health, 34, 528-533.
+ = significantly positive association. - = significantly negative association. CBC = Child Behavior Checklist (the higher the score, the more the
behavioral problem), total problem behavior in CBCL includes internalizing and externalizing behaviors. DBC = Developmental Behavior Checklist (the
higher the score, the more the behavioral problem), total problem behavior in DBC includes disruptive behaviors self-absorbed behaviors, and
communication disturbance. CSHQ = Child’s Sleep Habit Questionnaire (the higher the score, the greater the frequency of problem sleep behavior).
GARS = Gilliam Autism Rating Scale (the higher the score, the more the autistic symptom). ADI-R = Autism Diagnostic Interview-Revised (the higher
the score, the more the autistic symptom). BEDS = Behavioral Evaluation of Disorders of Sleep Scale (the higher the score, the more the sleep problem).
X = significant associations mentioned in studies. SDB = sleep-disordered breathing.
54
Table4. Associations between sleep problems and awakening behaviors in subjects with ASD on objective measures
Instruments Instruments Studies
Sleep parameters +, - Daytime behaviors Elia et al. Limoges et al.
Polysomnography PEP-R (passed items)
Sleep latency - Perception X
Sleep stage shifts - X
Night waking - X
Time in bed + X
Sleep stage shifts - Eye-hand coordination X
First REM latency - X
Night waking - X
Sleep period time + X
CARS
Sleep period time - Visual response X
Night waking + X
Total sleep time - Non-verbal communication X
Density of REM - Relating to people X
CARS
Density of REM - Activity level X
55
Table 4. (Continued)
Instruments Instruments Studies
Sleep parameters +, - Daytime behaviors Elia et al. Limoges et al.
Polysomnography Youth Self-Rating Scale
REM % + Internalizing problem behavior X
Note. From “Sleep in subjects with autistic disorder: A neurophysiological and psychological study,” by M. Elia, R. Ferri, S. A. Musumeci, S. D. Gracco,
M. Bottitta, C. Scuderi, et al., 2000, Development of Brain Dysfunction, 22, 88-92. “Atypical sleep architecture and the autism phenotype,” by E.
Limoges, L. Mottron, C. Bolduc, Berthiaume, and R. Godbout, 2005, Brain, 128, 1049-1061.
+ = significantly positive association. - = significantly negative association. PEP-R = Psychoeducaitonal Profile-Revised (the more passing items, the
better ability). CARS = Childhood Autism Rating Scale (the higher the score, the more severe). X = significant associations mentioned in studies.
56
Chapter III: Methodology

This chapter describes the methodology used in this study. It includes an
overview of the study, a description of the participants, the instruments employed,
the procedure, and the methods of the data analysis.

Overview of the Study
Higher percentages of sleep problems are reported for children with autism
spectrum disorders (Honomichl et al., 2002; Patzold et al., 1998; Richdale, 1999),
as well as a higher degree of sleep-related behavioral problems, such as poor
social skills, compared to typically developing children (Hoffman et al., 2005;
Malow et al., 2006; Patzold et al., 1998; Schreck et al., 2004). Moreover, sleep
problems are considered to be related to sensory processing problems (DeGangi,
2000; Spitzer & Roley, 2001), and sensory processing problems are also thought
to be related to social skills (Case-Smith & Miller, 1999). However, the puzzle of
whether sleep problems, sensory processing difficulties, and social participation
are related in children with autism spectrum disorders has not been studied yet.
Therefore, this pilot study was designed to investigate the question. The Child’s
Sleep Habits Questionnaire (CSHQ) and a researcher-developed sleep history
form were used to gather information on sleep problems. The Sensory Processing
Measure Home Form-R was used to measure social participation and sensory
processing difficulties. The purpose of this pilot study was to begin to explore
sleep problems in a clinical sample of children aged from 5 to 9 years and 4

57
months with autism spectrum disorders and to investigate relationships among
sleep problems, sensory processing difficulties, social participation, and
chronological age.

Participants
Children with autism spectrum disorders, who were receiving pediatric
occupational therapy in a USC affiliated clinic, were selected based on two
inclusion criteria. First, participants needed to have autism spectrum disorders,
including autistic disorders, Asperger’s syndrome, and PDDNOS. Second, their
chronological ages needed to range from 5 to 9 years and 4 months. Their
diagnoses had been given by educational psychologists, psychologists, or
psychiatrists from school districts, regional centers, or hospitals and documented
in their Individualized Education Program (IEP) reports stored in the clinic
records.
To determine the desirable sample size for this study, a power analysis was
conducted. A population correlation .33 was presumed for every given variable.
In order to reach a significance level of .05 with a power of .8, the estimated
sample size was 60 using a one tailed hypothesis test. In other words, 60
participants were planned to be sampled into this study. However, 33 children
were actually sampled due to the time constraint of completion of the researcher’s
MA program.

58
Instruments
Sleep measures
The Child’s Sleep Habit Questionnaire (CSHQ) is a sleep questionnaire
designed for 4 to 12 year old children, who are suspected to have sleep
disturbances (Owens et al., 2000). The CSHQ is not intended to be used to
determine diagnoses of sleep disorders, but for pre-screening possible sleep
problems, which often occur in this age group. The CSHQ contains both a total
score and eight subscales: bedtime behavior, sleep onset delay, sleep duration,
sleep anxiety, night waking, parasomnias, sleep breathing, and daytime
sleepiness.
The CSHQ was designed based on clinical symptoms presented in the
International Classification of Sleep Disorders (ICSD) diagnoses (American
Sleep Disorder Association, 1990). In the CSHQ, parents are asked to recall
events about medical and behavioral sleep problems that happened during the
past week. If the past week was unusual for children, a typical week is asked to
be recalled. Parents rate those events on a 3-point scale: 3= usually/five to seven
times a week, 2= sometimes/two to four times a week, and 1= rarely/ zero to one
time per week. Parents also answer yes or no to each question to indicate the
presence of sleep problems on each item.
With sensitivity of .80 and specificity of .72, the CSHQ has been shown to
validly differentiate between children diagnosed with sleep disorders and a
normative group of community children (Owens et al., 2000). Children having
scores higher than or equal to the cutoff point of 41 are considered to have sleep
problems. The CSHQ manual reports internal consistency coefficients of .68 for a
59
community sample and of .78 for a clinic sample. The internal consistency
coefficients of the 8 CSHQ subscales range from .36 to .93. Test-retest reliability
correlation coefficients range from .62 to .79 (Owens et al., 2000).
In the sleep behavior section of the CSHQ, a question asking about the
usual amount of sleep each day, combining nighttime sleep and naps, was adapted
by the researcher to record only night time sleep. In this way, the answer parents
give to this question can be confirmed by the subtraction of the answers of two
other questions of the CSHQ: the wake-up time and the bed time.
A sleep medical history form was designed by the researcher for this study
to collect data regarding sleep medical history. Questions of primary diagnoses
and sleep diagnoses were included. Questions of whether children took
medication for sleep problems or for their primary diagnoses, whether parents
had sleep problems, and whether parents thought their children had sleep
problems were also asked. Participants’ gender and age were also asked in the
sleep medical history form.

Measures of social participation and sensory processing difficulties
The research edition of the Sensory Processing Measure Home Form (SPM
Home Form-R) (Parham & Ecker, in press) is a questionnaire measuring
children’s sensory processing difficulties and social participation in the home
environment. The SPM Home Form-R, completed by the parents or guardian,
was designed for children aged 5 to 12 years.
The SPM Home Form-R has two parts: social participation and sensory
processing difficulties. Part I contains questions about usual responses of social
60
participation in the social environment. Part II contains sensory questions about
unusual responses in 6 sensory modalities, plus a separate section of questions
about the child’s ideas and planning. The SPM Home Form-R has 4 anchor points
across all items: 1=never, 2=occasionally, 3=frequently, and 4=always. Those
anchor points represent the frequency of the behavior asked. In Part I, a higher
score represents better social participation, while in Part II, a higher score refers
to more frequent sensory processing difficulties. Parents rate children’s social and
sensory-related responses based on children’s typical behavior during the past
month.
The Sensory Scale of the SPM Home Form-R contains items regarding 6
sensory modalities: Vision, hearing, taste and smell, vestibular functions,
proprioceptive function, and touch. Most of these items were derived from the
research version 4 of the Evaluation of Sensory Processing (ESP). The internal
consistency, construct validity, criterion validity, and inter-rater reliability of the
ESP were investigated. Su’s study (2002) of sensory integration theory indicated
that the Cronbach’s alphas across 5 sensory modalities - vision, hearing,
vestibular function, proprioception, and touch - ranged from .69 to .94. More
importantly, Su showed that the sensory systems form valid factors. Most items
of the ESP significantly differentiate between children with autism and typically
developing children (VerMaas-Lee, 1999). Chang (1999) found that > 75 % of
fathers and mothers of children with sensory integration dysfunction and typically
developing children reported their ratings on the ESP with no more than 1 point
difference, indicating that most of fathers and mothers of those children were in
agreement when reporting their children’s sensory processing difficulties.
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Procedure
Data collection was implemented at Pediatric Therapy Network (PTN) in
Torrance, California. Pediatric Therapy Network is a non-profit pediatric therapy
center, serving over one thousand children with special needs.
Flyers with the information on the study and the phone numbers of the
researcher were posted on an information board at PTN, as well as put on the
front desk by the clinical entrance, so that parents or caregivers of potential
participants could easily obtain it. If parents or caregivers were interested in the
study, they would call the researcher. Then on the phone parents or caregivers
were reconfirmed for their participation and requested to meet with the researcher.
In the meeting, the researcher explained the details of the study and the rights of
participants in it to the parents or caregivers, and then requested that they sign an
IRB-approved informed consent and fill out 3 survey forms. The 3 survey forms
were the CSHQ, the SPM Home Form-R, and a sleep medical history
questionnaire. One of the three survey forms, the SPM Home Form-R, was a
routine clinical assessment at PTN. Therefore, some children already had their
SPM Home Form-R filled out and stored in files. Parents of those children were
not asked to fill out the SPM Home Form-R again. Those forms were obtained
with their primary therapists releasing their forms from their clinical records. The
released forms were included in this study.
Because the normative scores on the SPM Home Form-R were not yet
available, raw scores were used. The researcher summed the sensory score and
social score on the SPM Home Form-R and the sleep scores on the CSHQ, filled
out the data collection tables, entered those data to computer, and analyzed them
62
with SAS. A research assistant monitored the data entry for all cases for accuracy.
The research assistant was not allowed to access any identifying data nor was any
identifying information stored on the computer.

Data Analysis
Data were analyzed with SAS version 8.0 for Windows XP. Data analysis
was separated into three parts in order to answer the three research questions in
this study.

Data analysis for research question 1: In a clinical sample of children aged 5 to 9
years and 4 months referred to occupational therapy, what is the prevalence of
sleep problems?
In the first part of the data analysis, participants’ characteristics including
demographics, sleep, sensory processing, and social participation were described
with frequencies, percentages, means, medians, standard deviations, and ranges.
Sleep problems were identified in two ways: CSHQ scores G 41 and parents’
perceptions toward their children’s overall sleep problems.

Data analysis for research question 2: In the sample, what are common sleep
patterns?
For this part of the data analysis, children were grouped into three groups,
based on the consistency of their sleep problems reported both on the CSHQ total
score and parental responses on the question of whether the child has a sleep
problem asked in the sleep medical history form. Group A is comprised of
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children for whom sleep problems were consistently indicated both on CSHQ
total score (G 41) and parent responses on the sleep medical form. Group B
consists of children for whom sleep problems were inconsistently reported on the
CSHQ and the sleep medical history form. Parents of group B reported CSHQ
total scores G 41, indicating sleep problems, but answered “no” to the question on
the sleep medical history form. Group C contains children whose parents
consistently indicated no sleep problems both on CSHQ total score (<41) and the
question asked in the sleep form.
Sleep patterns were depicted by the presence of sleep disturbances and the
severity of sleep problems. Presence of sleep disturbances was measured by total
number of yes responses to questions parents answered on the CSHQ. Severity of
sleep problems was measured by the CSHQ subscales scores.
In order to observe the differences in sleep patterns in these three groups,
numbers and percentages were used to summarize the presence of sleep
disturbances. The Kruskal Wallis test and Wilcoxon rank sum tests with
Bonferroni adjustment were used to test the between-group and within-group
differences in the ordinal data related to the severity of sleep problems. The
ANOVA on ranks and T-test with Scheffe’s adjustment were used to test the
between-group and within-group differences in the continuous data related to
sleep problems.

64
Data analysis for research question 3: Are sleep problems and sensory processing
difficulties negatively correlated with social participation? Are sleep and sensory
processing problems negatively correlated with chronological age?
In this part of the data analysis, Spearman correlation coefficients were
computed to observe the correlations among sleep problems, sensory processing
difficulties, social participation, and chronological age. Correlations among
subscales of sleep measures and sensory processing measures, social participation,
and chronological age were also generated. Since the type of our data is ordinal,
Spearman correlation coefficients were used.

65
Chapter IV: Results

This chapter presents the findings of this study in order to answer the three
research questions: First, in a clinical sample of children with autism spectrum
disorders referred to occupational therapy, what is the prevalence of sleep
problems? Second, in this sample, what are common sleep patterns? Third, are
sleep problems and sensory processing difficulties negatively correlated with
social participation, and are sleep and sensory processing problems negatively
correlated with chronological age? In order to systematically present the findings
for the three research questions, the results are presented in the following three
sections: 1. Basic description of participants’ characteristics including
demographic characteristics, sleep characteristics, sensory processing difficulties,
and social participation, 2. Sleep patterns: Presence of sleep disturbances and
severity of sleep problems, and 3. Correlations among measures.

Description of Participants’ Characteristics
Demographic characteristics
Children with autism spectrum disorders with a mean age of 6 years and 6
months were sampled (N=33). Participants’ gender, diagnoses, and race are
summarized in Table 5.

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Table 5 Demographic characteristics of participants
Characteristics Participants (N = 33)
Mean ± SD Range

Age (yr) 6.6 ± 1.2 5-9.4

Frequency %
Gender
F: 2 6%
M: 31 94%
Diagnoses
Autism 31 94%
Asperger’s 1 3%
PDDNOS 1 3%
Ethnicity
Hispanic: 4 12%
Caucasian: 9 27%
African American: 1 3%
Asian: 9 27%
American Indian: 1 3%
Pacific Islanders: 1 3%
Mixed: 8 24%
Note. PDDNOS = pervasive developmental disorders not otherwise specified. SD =
standard deviation.

Sleep characteristics
Tables 6a, 6b, and 6c present descriptive information on sleep
characteristics. Due to missing data, the total number of participants for each
variable varies in the Tables.
Parents of 35% of the sample answered yes when they were asked whether
they thought their children had sleep problems; 78% of participants had CSHQ
total scores G 41, indicating that 78% of children had sleep problems. Only one
child was reported to have a medical diagnosis indicating a sleep problem. The
specific diagnosis was not given. Two children reportedly took melatonin for
their sleep problems. Four children reportedly took medication for their primary
diagnoses. One of these four took zonisamide for partial seizures and risperidone
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an antipsychotic medication. Another one took guanfacine, a medication for
attention deficit problems, particularly for the symptoms of impulsivity.
Medication for the remaining two was not specifically identified. Eight parents
reported that they had sleep problems (See in Table 6a).
Table 6a. Sleep characteristics obtained from the sleep medical history
questionnaire and the CSHQ
Characteristics Participants
N Frequency %
Parent perception of whether child has
sleep problems 31
Yes 11 35%
No 20 65%
CSHQ total 32
G 41 25 78%
< 41 7 22%
Medical diagnosis of sleep disorder 31
With 1 3%
Without 30 97%
Medication for sleep problems 32
Yes 2 6%
No 30 94%
Medication for primary diagnoses 31
Yes 4 13%
No 27 87%
Sleep problems in parents 32
Yes 8 25%
No 24 75%
Table 6b displays the continuous data of sleep characteristics obtained
from the CSHQ. The average amount of night sleep was 595 minutes (9.9 hours)
per day. The average duration of night waking was 14.30 minutes per night.
Fourteen (46%) parents of participants reported that their children had 0 minutes
of night waking. Seven (23%) parents reported that their children had over 20
minutes of night waking.

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Table 6b. Amount of night sleep and duration of night waking obtained from the
CSHQ
Characteristics Participants
N M (± SD) Range
Amount of night sleep (min) 31 594.68 (± 32.94) 525-660
Duration of night waking (min) 30 14.30 (± 28.18) 0-120
Note. CSHQ = Child’s Sleep Habits Questionnaire. M = mean. SD = standard deviation.
Min = minutes.

Table 6c displays the ordinal data related to sleep problems obtained from
the CSHQ. Numbers of items in each subscale vary. Means, medians, standard
deviations, and ranges of the total score and scores of items of the CSHQ are
presented. Mean and median of CHSQ total are both above the CSHQ cutoff
score of 41, indicating sleep problem based on previous CSHQ research.
Table 6c.The CHSQ total and subscale scores
Characteristics (# of items) Participants (N=32)
Mean (± SD) Median Range
CSHQ Total (33) 46.34 (± 8.43) 44.00 35-61
Subscales
Bedtime resistance (6) 10.22 (± 3.24) 11.00 6-15
Sleep onset delay (1) 1.53 (± 0.67) 1.00 1-3
Overall sleep duration (3) 4.25 (± 1.61) 3.00 3-8
Sleep anxiety (4) 6.53 (± 2.12) 6.00 4-12
Freq of night waking (3) 4.50 (± 1.72) 4.00 3-9
Parasomnias (7) 9.16 (± 1.42) 9.00 7-12
Sleep breathing (3) 3.66 (± 1.10) 3.00 3-7
Daytime sleepiness (8) 10.13 (± 2.78) 10.00 6-17
Note. CSHQ = Child’s Sleep Habit Questionnaire. SD = standard deviation.

Sensory processing difficulties and social participation
Table 7 displays the sensory and social data obtained form the SPM Home
Form-R. Due to missing data, the numbers of valid data vary in the table. Means,
medians, standard deviations, and ranges are summarized.

69
Table 7. Sensory processing difficulties and social participation
SPM Home Form-R Participants
N Mean (± SD) Median Range
Part I: Social 32 51.38 (± 07.82) 51.00 32-67
Part II: Sensory 23 259.52 (± 49.53) 284.00 193-378
Subscales
Vision 32 43.66 (± 10.53) 42.59 29-65
Hearing 32 30.28 (± 06.46) 30.50 21-45
Touch 32 60.56 (± 14.59) 59.00 38-104
Taste/smell 32 18.94 (± 04.13) 19.00 12-28
Proprioception 32 31.00 (± 06.91) 31.00 19-49
Vestibular functions 24 36.25 (± 09.29) 33.00 24-59
Ideas and planning 23 35.39 (± 05.95) 35.00 24-45
Note. SD = standard deviation.

Sleep Patterns
Sleep patterns were designated by the presence of sleep disturbances and
severity of sleep problems. Presence of sleep disturbances refers to the
accumulation of yes responses to items parents answered on the CSHQ. Severity
of sleep problems refers to the scores measured with the CSHQ subscales.
To describe sleep patterns in our sample, participants were grouped into
three groups, based on the consistency of their sleep problems reported both on
the CSHQ total score and parent responses on the question of whether the child
has a sleep problem asked in the sleep medical history form. Group A is
comprised of children for whom sleep problems were consistently indicated both
on CSHQ total score (G 41) and parent responses on the sleep medical form.
Group B consists of children for whom sleep problems were inconsistently
reported on the CSHQ and the sleep medical history form. Parents of group B
reported CSHQ total scores G 41, indicating sleep problems, but answered “no” to
the question on the sleep medical history form. Group C contains children whose
parents consistently indicated no sleep problems both on CSHQ total score (<41)
and the question asked in the sleep form.
70
The reason why we grouped participants in this way is that data regarding
the presence of global sleep problems as measured by CSHQ total score and
parent responses on the question of whether the child has a sleep problem asked
in the sleep medical history form indicate the existence of these three distinct
groups of participants. Therefore, the three groups of children may demonstrate
different presence of sleep disturbance and severity of sleep problems. Because of
missing data for two children, the total number of children in this analysis was
31.

Presence of sleep disturbances
Table 8 displays the numbers and percentages of participants whose parents
reported yes to each item of the CSHQ, indicating that the sleep disturbance
represented by the item was presented in their children. Figure 2 displays the
percentages of the presence of sleep disturbances in the three groups of
participants.
In group A (n=11), each of the 31 sleep disturbances were more frequently
answered with a yes, compared to groups B and C. That means children whose
sleep problems were consistently indicated on both measurements of global sleep
problems collectively suffered from all of the specific sleep disturbances on the
CSHQ more frequently than children in groups B and C. Three sleep disturbances,
failing to fall asleep alone, struggling at bedtime, and having too little sleep were
most frequently answered with a yes. Eighty two percent of Group A parents
indicated that their children were not able to fall asleep alone in own bed , 73%

71
answered that struggling at bedtime was a sleep problem, and 64% indicated that
their children slept too little.
In group B (n=13), wetting the bed at night was identified as a problem by
5 (38%) of parents; other sleep disturbances were relatively rarely reported as
problems. In group C (n=7), two items, being afraid of sleep in the dark and
wetting the bed at night were reported as problems by 14% parents.
Severity of sleep problems
Medians of CSHQ total and subscale scores were compared for the three
groups using the Kruskal Wallis test and Wilcoxon rank sum tests with
Bonferroni adjustment (See in Tables 9a and 9b). Comparisons on amount of
night sleep and duration of night waking were also performed with ANOVA on
ranks (See in Table 10) and T-test with Scheffe’s adjustment.
Table 9a displays the between-group comparisons using the Kruskal Wallis
test on CSHQ total and subscale scores. CSHQ total score (p < .001) and 5 of the
8 subscale scores: bedtime resistance (p < .001), overall sleep duration (p = .004),
sleep anxiety (p = .008), frequency of night waking (p < .001), and daytime
sleepiness (p = .001) are significantly different among groups.
In order to conduct a more rigorous test of differences among these three
groups, Wilcoxon rank sum tests with Bonferroni adjustment was performed.
Since in total 6 comparisons were among these three groups, the adjusted
alpha .0083 was obtained by dividing the .05 of original alpha with the 6
comparisons. In other words, if the p was less than .0083, the difference was
significant. Because of no significant difference among these three groups in
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sleep onset delay, parasomnias, and sleep breathing, within-group comparisons
didn’t need to be performed on them.
Table 9b displays that between group A and B frequency of night waking
has a significant difference, which points out that group A parents reported more
frequent night waking than group B parents. Significant differences between
group A and C are in CSHQ total, bedtime resistance, overall sleep duration,
frequency of night waking, and daytime sleepiness. Compared to Group C
parents, group A parents reported their children had more overall sleep problems,
resisted to go to bed more, generally slept less, more frequently waked up during
the night, and had more severe daytime sleepiness. Between group B and C,
CSHQ total, bedtime resistance, sleep anxiety, and daytime sleepiness show
significant differences. In other words, compared to group C parents, group B
parents indicated that their children had more overall sleep problems indicated on
CSHQ total score, resisted to go to bed more, had more sleep anxiety, and
showed more sleepiness in the daytime.
In order to analyze group differences in amount of night sleep and duration
of night waking, ANOV A on ranks were performed. Table 10 displays that
between-group difference is only significant in duration of night waking. With
T-test with Scheffe’s adjustment, the difference was found between group A and
group C. In other words, group A parents reported their children woke up in the
night with longer duration than group C parents.
73
Table 8. Numbers and percentages of children whose parents reported
with a yes on each item of the CSHQ
Item of the CSHQ Group A Group B Group C
n (%) n (%) n (%)
1 3(27) 1 (8) 0 (0)
2 5(45) 0 (0) 0 (0)
3 9(82) 1 (8) 0 (0)
4 6(55) 2 (16) 0 (0)
5 6(55) 1 (8) 0 (0)
6 8(73) 2 (16) 0 (0)
7 2(18) 0 (0) 1 (14)
8 6(55) 0 (0) 0 (0)
9 7(64) 1 (8) 0 (0)
10 1 (9) 0 (0) 0 (0)
11 3 (27) 0 (0) 0 (0)
12 2 (18) 5 (38) 1 (14)
13 0 (0) 0 (0) 0 (0)
14 5 (45) 2 (16) 0 (0)
15 1 (9) 0 (0) 0 (0)
16 4 (36) 0 (0) 0 (0)
17 2 (18) 2 (16) 0 (0)
18 2 (18) 0 (0) 0 (0)
19 2 (18) 0 (0) 0 (0)
20 4 (36) 0 (0) 0 (0)
21 2 (18) 2 (16) 0 (0)
22 1 (9) 1 (8) 0 (0)
23 2 (18) 0 (0) 0 (0)
24 6 (55) 0 (0) 0 (0)
25 2 (18) 0 (0) 0 (0)
26 4 (36) 0 (0) 0 (0)
27 5 (45) 0 (0) 0 (0)
28 1 (9) 1 (8) 0 (0)
29 2 (18) 1 (8) 0 (0)
30 2 (18) 0 (0) 0 (0)
31 3 (27) 1 (8) 0 (0)
Note. Group A (n =11) = children for whom sleep problems were
consistently indicated both on CSHQ total score (G 41) and parent responses
on the question of whether the child has a sleep problem asked in the sleep
medical history form. Group B (n =13) = children for whom sleep problems
were inconsistently reported on the CSHQ and the sleep medical history
form. Group B parents reported CSHQ total scores G 41, indicating children’s
sleep problems, but answered a no to the question on the sleep medical
history form. Group C (n =7) = children who had no sleep problems
consistently indicated both on CSHQ total score (<41) and the sleep form.

74
Figure 2. Percentages of children on the presence of sleep disturbances
Note. Dot line with squares = group A (n=11). Broken line with circles = group B (n=13). Non-broken line with triangles = group C (n=7). Item 1 = go to
bed at different time at night. Item 2 = fall asleep not within 20 minutes. Item 3 = fail to fall asleep. Item 4 = fall asleep in parents’ or sibling’s bed. Item
5 = need parents in the room to fall asleep. Item 6 = struggle in bed (cries, refuse to stay in bed, etc). Item 7 = be afraid of sleeping in the dark. Item 8 =
be afraid of sleep alone. Item 9 = sleep too little. Item 10 = not sleep the right amount. Item 11 = sleep different amount each day. Item 12 = wet the bed
at night. Item 13 = talk during sleep. Item 14 = be restless and move a lot during sleep. Item 15 = sleepwalk during the night. Item 16 = move to
someone’s bed during the night. Item 17 = grind teeth during sleep. Item 18 = snore loudly. Item 19 = seem to stop breathing during sleep. Item 20 =
snort and/or gasp during sleep. Item 21 = having trouble sleeping away from home. Item 22 = awaken during night screaming, sweating, and
inconsolable. Item 23 = awaken alarmed by frightening dream. Item 24 = awaken once during the night. Item 25 = awaken more than once during the
night. Item 26 = wake up not by himself/herself. Item 27 = wake up in negative mood. Item 28 = wake up by adults or siblings. Item 29 = have difficulty
getting out of bed in the morning. Item 30 = take a long time to become alert in the morning. Item 31 = seem tired.
0
10
20
30
40
50
60
70
80
90
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Item of CSHQ
percentages (%)
75
Table 9a. Between-group comparisons of median CSHQ total and subscale scores
Characteristics Group A (n =11) Group B (n =13) Group C (n =7)
LQ Median UQ LQ Median UQ LQ Median UQ p
CSHQ total 48 52 61 43 44 48 35 36 36 <.001
CSHQ subscales
Bedtime resistance 9 12 15 8 11 13 6 6 7 <.001
Sleep onset delay 1 2 3 1 1 2 1 2 2 .267
Overall sleep duration 4 6 7 3 3 4 3 3 3 .004
Sleep anxiety 5 8 9 6 7 7 4 4 5 .008
Freq. of night waking 5 6 8 3 4 4 3 3 3 <.001
Parasomnias 9 9 10 8 10 10 7 8 9 .177
Sleep breathing 3 3 5 3 3 4 3 3 4 .943
Daytime sleepiness 10 12 14 10 10 11 7 7 8 .001
Note. Kruskal Wallis test. Alpha = .05. LQ = lower quartile. UQ = upper quartile.
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Table 10. Between-group comparisons of mean amount of night sleep and duration of night waking
Measures A (n =11) B (n =13) C (n =7)
Mean (± SD) Mean (± SD) Mean (± SD) F p
Amount of night sleep (min) 599.5 (± 37.2) 594.1 (± 29.8) 587.1 (± 35.1) 0.12 .89
Duration of night waking (min) 33.5 (± 41.6) 7.2 (± 11.5) 0 (± 0) 8.97 .001
Note. ANOVA on ranks. Alpha=.05. SD = standard deviation.
Table 9b. Within-group comparisons of median CSHQ total and subscale scores
Measures A-B A-C B-C
Z p Z p Z p
CSHQ total 2.23 0.025 -3.46 <0.001* -3.58 <0.001*
CSHQ subscales
Bedtime resistance 0.96 0.334 -3.40 <0.001* -3.39 <0.001*
Overall sleepduration 2.54 0.011 -2.80 0.005* -0.89 0.375
Sleep anxiety 1.10 0.264 -2.36 0.018 -2.93 0.003*
Freq. of night waking 2.78 0.005* -3.14 0.002* -1.72 0.086
Daytime sleepiness 1.20 0.229 -2.75 0.006* -3.49 <0.001*
Note. Wilcoxon rank sum tests with Bonferroni adjustment. Alpha=.0083. Two-sided. * = significant difference.
77
Correlations among measures
Spearman correlation coefficients were performed to observe the
correlations among measures. Because our sample size was not large enough to
generate meaningful correlations within each group, correlations were computed
for the total sample. Since the type of our data is ordinal, Spearman correlation
coefficients were used.
Table 9 displays Spearman correlation coefficients. Chronological age was
positively significantly correlated with sensory total score (r=.46, p=.03), visual
score (r=.46, p=.008), and proprioception score (r=.44, p=.01). That means the
older the participants, the worse their overall sensory function, visual processing,
and proprioception. However, social participation was not significantly correlated
with chronological age.
Moreover, chronological age was negatively significantly associated with
duration of night waking (r=-.41, p=.02), CSHQ total score (r=-.39, p=.03),
bedtime resistance (r=-.042, p=.02), sleep anxiety (r=-.35, p=.05), frequency of
night waking (r=-.44, p=.01), and daytime sleepiness (r=-.39, p=.02). In other
words, the older the participants, the shorter the duration of night waking, the
better the overall sleep function, the less the bedtime resistance, the less frequent
the night waking, the less the daytime sleepiness, and less sleep anxiety.
Amount of night sleep was negatively significantly correlated with
vestibular functions (r=-.50, p=.02). The longer the participants slept at night, the
better their vestibular functions were. Duration of night waking was negatively
significantly associated with proprioception (r=-63, p <.001). The longer duration
participants were awake at night, the worse their proprioception was.
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Parasomnias were negatively significantly correlated with social participation
(r=-.42, p=.02). The more severe parasomnias participants had, such as wetting
bed, talking during sleep, being restless and moving a lot, and sleepwalking, the
worse their social skills were.

79
Table 11. Correlations(r) among variables
Variables Social Sensory
Vision Hearing Touch Taste / Smell Prop. Vest. Ideation Age
Social 1.00 -.29 -.30 -.002 -.28 -.12 -.28 -.29 -.33 .08
Age .08 .46* .46* .24 .27 .27 .44* .38 .33 1.00
Amount of night sleep -.03 -.27 -.15 -.09 .002 .12 -.19 -.50* -.19 -.25
Duration of night waking .16 -.30 -.12 .16 .05 -.02 -.63* -.28 -.16 -.41*
CSHQ total -.16 -.06 -.08 .10 .11 .02 -.17 -.09 -.03 -.39*
CSHQ subscales
Bedtime resistance -.18 -.08 -.11 .09 .20 .04 -.24 -.11 -.16 -.42*
Sleep onset delay .02 -.09 .18 .09 .12 -.10 -.13 .06 .25 .14
Overall sleep duration -.15 -.08 -.03 -.06 -.07 -.02 -.06 .14 .05 -.22
Sleep anxiety -.23 -.09 -.04 .03 .16 .04 -.28 -.09 -.16 -.35*
Freq. of night waking .13 -.32 -.20 -.03 -.17 -.21 -.32 -.24 -.19 -.44*
Parasomnias -.42* .27 .02 .04 .26 .01 .32 .15 .14 -.15
Sleep breathing -.13 -.09 -.13 -.23 -.19 .06 .001 .05 -.14 -.23
Daytime sleepiness -.14 -.06 -.15 .13 .06 .03 -.07 -.06 .18 -.39*
Note. Social = social participation measured in the SPM Home Form-R (the higher the score, the better the social skills). Sensory = sensory
processing difficulties measured in the SPM Home Form-R (the higher the score, the worse the sensory function). CSHQ = Child’s Sleep Habit
Questionnaire (the higher the score, the more the sleep problems).
r = Spearman r. * = PW .05. Prop. = proprioception. Vest. = vestibular functions. N varies in each correlation ranging from 23 to 33.
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Chapter V Discussion

In this chapter, interpretation and implication of results, clinical
significance, limitations, and suggestions for future studies are provided.
In the implications and interpretation section, answers for our three
research questions are first given. Then, comparisons of our findings to those of
previous studies are then provided. After that, interpretation and implications of
the comparisons described. Besides the findings specifically pointing to our three
research questions, other findings are also presented.

Interpretation and Implications of Findings

Research question 1: In a clinical sample of children aged 5 to 9 years and 4
months with autism spectrum disorders referred to occupational therapy, what is
the prevalence of sleep problems?
In our sample, if the existence of global sleep problems is defined by parent
responses on the question of whether you think in general your child has sleep
problems in the sleep history form, the prevalence of sleep problems is 35%. If
sleep problems are determined with the CSHQ cutoff score of G 41, the
prevalence is 78%.
Previous studies of children with autism spectrum disorders (Patzold et al.,
1998; Richdale, 1999) that examined parent perceptions of children’s global sleep
problems indicates a rate ranging from 44% to 83%. Honomichl et al. (2002)
using the CSHQ found that 54% of children with PDD in their sample had sleep
problems. Comparing those rates with ours, our rate of 35% is low.
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The lower rate of parent perceptions of children’s global sleep problems on
our question in the sleep medical history form may result from the fact that this
question directly follows the question of whether your child has been diagnosed
with a sleep disorder. The sequence of these two questions might mislead parents
to consider that the sleep problems in the earlier question refer to medical
diagnosed sleep disorders. Moreover, parent perceptions of children’s specific
sleep patterns, such as co-sleeping or bed wetting probably affect parents’
judgments of the presence of children’s global sleep problems. Some parents in
our sample did not consider co-sleeping or wetting bed as sleep problems, and
answered a no to our question in the medical history form. Since the CSHQ
identifies those patterns as sleep problems, their children’s CSHQ total scores
were over 41.
Regarding whether parents of children with autism spectrum disorders tend
to report their children’s sleep problems, previous studies have no consistent
agreement on it. Hering et al. (1999) argued for the possibility of parent over
reporting children’s sleep problems; however, Cotton & Richdale (2006),
Hoffman et al. (2005), and Patzold et al. (1998) positively accepted parental
reports. As for our study, parent perceptions of children’s global sleep problems
indicated in our medical history form were less sensitive than the CSHQ cutoff
score to detect children’s sleep problems; illustrating another possible explanation
that parents of children with autism spectrum disorders being referred to OT
might less notice their children’s global sleep problems so that they might not be
able to immediately recognize possible global sleep problems in their children as

82
they are generally asked about them. In other words, they might easily identify
their children’s sleep problems by presenting specific sleep patterns.

Research question 2: In this sample, what are common sleep patterns?
In order to carefully answer this question, sleep patterns in our three groups
are presented separately. Group A is comprised of children whose sleep problems
were consistently indicated both on CSHQ total score (G 41) and parent responses
on the sleep medical form. More parents in this group answered a yes on each
sleep disturbance in the CSHQ, indicating that more sleep problems may be
presented in group A children. Seven sleep disturbances that over 50% of Group
A parents reported with a yes were failing asleep alone in own bed, falling asleep
in parents’ or sibling’s bed, needing parents in the room to fall asleep, struggling
at bedtime, being afraid of sleeping alone, sleeping too little, and awakening once
during the night. Those sleep disturbances are categorized into three CHSQ
subscales: bedtime resistance, sleep duration including night sleep and daytime
naps, and night waking. In other words, sleep patterns we found in this group
were more bedtime resistance, less overall sleep duration, and more night waking.
Comparing our findings with those in the previous studies in children with
autism spectrum disorders (Cotton & Richdale, 2006; Couturier et al., 2005;
Diomedi et al., 1999; Elia et al., 2000; Limoges et al., 2005; Patzold et al., 1998;
Schreck & Mulick, 2000) our findings are in agreement.
Group B has children whose sleep problems were inconsistently reported
on the CSHQ and the sleep medical history form. Group B parents reported
CSHQ total scores G 41, indicating children’s sleep problems, but answered a no
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to the question on the sleep medical history form. In this group, wetting bed was
the most frequent problem reported by their parents. A higher percentage of
wetting bed in Group B was reported than that in Group A, indicating that parents
in group A may not consider bed wetting as troublesome as other sleep
disturbances, such as failing to fall asleep alone and struggling at bedtime.
Group C contains children who had no sleep problems consistently
indicated both on CSHQ total score (<41) and the sleep medical history form.
Being afraid of sleeping in the dark and wetting bed were two problems reported
by Group C parents.
Differences in severity of sleep problems measured by the CSHQ subscale
scores were tested among our three groups. Significant between-group
differences were in overall sleep problems measured by the CSHQ total score,
bedtime resistance, overall sleep duration, sleep anxiety, frequency and duration
of night waking, and daytime sleepiness.
Specifically, the differences in overall sleep problems, bedtime resistance,
overall sleep duration, frequency and duration of night waking, and daytime
sleepiness were between group A and group C. That means children whose sleep
problems were consistently indicated both on CSHQ total score (G 41) and parent
responses on the sleep medical form may have more overall sleep problems,
resist to go to bed more often, have less overall sleep duration, awaken in the
night more often and longer, and have more daytime sleepiness, compared to
children who had no sleep problems consistently indicated both on CSHQ total
score (<41) and the sleep medical history form.

84
Between group B and C, the differences were indicated in overall sleep
problems, bedtime resistance, sleep anxiety, and daytime sleepiness. In other
words, children whose sleep problems were inconsistently reported on the CSHQ
and the sleep medical history form may still have more severe sleep problems
than those whose parents consistently reported non sleep problems on both
measurements of global sleep problems.
The difference in frequency of night waking between group A and B along
with the difference in the same measure between group A and C demonstrates that
Group A children may awaken during the night most frequently, compared to
Group B and C children.
Another difference we found in duration of night waking was indicated
between group A and group C. In order words, group A children may awaken in
the night with longer duration than group C children.

Research question 3: Are sleep and sensory processing problems negatively
correlated with chronological age? Are sleep problems and sensory processing
difficulties negatively correlated with social participation?
Overall sleep problems and chronological age were significantly and
negatively correlated. This finding may imply that as children with autism
spectrum disorders mature, their sleep problems may be less. Moreover, duration
and frequency of night waking, CSHQ total score, bedtime resistance, sleep
anxiety, and daytime sleepiness were negatively and significantly associated with
age, also indicating that the older the participants, the shorter the duration of

85
night waking, the better the overall sleep function, the less the bedtime resistance,
the less frequent the night waking, and the less the daytime sleepiness.
Our findings are in agreement with those in previous studies (Patzold et al.,
1998; Richdale & Prior, 1995; Richdale, 1999). Richdale and Prior (1995) found
that younger children with autism spectrum disorders tend to have more sleep
problems. Patzold et al. (1998) discovered that younger children with autism
spectrum disorders tend to have more night waking. Richdale (1999) indicated
that older children with autism spectrum disorders might have fewer sleep
problems.
Sensory processing difficulties were positively and significantly correlated
with chronological age, which implies that sensory processing difficulties in
children with autism spectrum disorders may become more severe as they mature.
A possible reason might be that the sensory demands in children’s daily life are
much higher than the improvement of their sensory processing function along
with their growth. This possible explanation gives an alarm to therapists to be
more aware of the connection between children’s sensory processing function and
their daily life. Another possible reason is that older children in our sample might
start their treatments late. This possible reason also draws therapists’ attention to
consider the timing for those children to start therapy.
Moreover, although the CSHQ total score and sensory processing
difficulties were not significantly correlated, there were two significant
associations between sleep subscale scores and sensory subscale scores.
Vestibular functions were significantly and negatively correlated with amount of
night sleep, and proprioception was significantly and negatively associated with
86
duration of night waking. In other words, the longer the participants slept at night,
the better their vestibular functions were. The longer duration participants were
awake at night, the worse their proprioception was. These two findings may be
very important to sensory-based occupational therapy because it may imply that
amount of night sleep and duration of night waking may affect vestibular and
proprioceptive functions in children with autism spectrum disorders, or the other
way around, vestibular and proprioceptive functions might influence amount of
night sleep and duration of night waking. Future studies of the relationships of
sleep and sensory processing, especially vestibular-proprioceptive functions are
strongly recommended.
Considering the association between CSHQ total score and social
participation, although in our findings they were negatively correlated, the
correlation was not significant. These findings contradicted previous findings.
Limoges et al. (2005) indicated that total sleep time was significantly negatively
correlated with social dimension measured by the ADI-R. However, our findings
show that neither overall sleep duration, amount of night sleep, nor overall sleep
problems were significantly associated with social participation. Hoffman et al.
(2004) found that social interaction measured by the GARS was significantly
correlated with overall sleep duration, parasomnias, sleep breathing, daytime
sleepiness, and the CSHQ total score, whereas, except for parasomnias, none of
those had a significant association with social participation in our study. These
discrepancies may result from two reasons, sample size and the purpose of social
measurements. Hoffman et al. had 80 participants with autism spectrum disorders;
whereas we had 33. The instruments, ADI-R and GARS, were specifically
87
designed to screen or diagnose autism spectrum disorders so that their social
interaction questions may be more sensitive to the specific weaknesses of social
functions in children with autism spectrum disorders.
Among sub-sleep problems, parasomnias were significantly negatively
associated with social participation. The more severe parasomnias participants
had, such as wetting bed, talking during sleep, being restless and moving a lot,
and sleepwalking, the worse their social skills were. This is in agreement with
that in the Hoffman et al. study (2004). The possible reason underlying this
association is still unclear and, therefore, needs to be further studied in the future.
Insignificant associations between social participation and chronological
age, and between social participation and sensory processing difficulties dictate a
need for more studies with larger sample sizes to more carefully investigate their
relationships. They may imply that social participation in children with autism
spectrum disorders may be indirectly related to chronological age, or to sensory
processing. Instead, social participation may be directly relevant to other factors,
such as the ability to detect and interpret social cues, the flexibility to receive
constant changes in social context, the ability to sympathize and empathize with
others, and the ability to reciprocally speak to others with proper body language.
Studies investigating the interrelationships among those factors, social skills, and
sensory processing in children with autism spectrum disorders are highly
recommended.

88
Clinical Significance

The present study provides important information for pediatric
occupational therapists to refine their clinical reasoning. First of all, the two rates
of prevalence of sleep problems in children with autism spectrum disorders not
only show that sleep problems are indeed in this population, but also imply that
when parents are asked about their children’s overall sleep problems, they may
not be able to recognize those problems. However, the most common sleep
patterns, such as more bedtime resistance, less sleep duration, and more night
waking, seem to be more easily recognized by parents. Therefore, therapists need
to look for this information when interviewing parents
Moreover, more bedtime resistance, frequent night waking, and less overall
sleep duration in children with autism spectrum disorders might adversely affect
parents’ and other family members’ psychological statuses and occupational
orchestration resulting in decreased well being in the whole family (Cotton &
Richdale, 2006; Honomichl et al., 2002; Richdale et al., 2000). Although our
study didn’t investigate the effect of sleep problems in children with autism
spectrum disorders on the well being of other family members, therapists may
need not only to consider treatments on children, but also be concerned with
possible unbalance of family members’ occupation caused by children’s problem
sleep. Therefore, questions like whether specific sleep problems, such as settling
problems in their children, would increase family members’ stresses or affect
members’ night time management or routines may be also applied when
therapists interview parents.
89
Furthermore, with consideration of the relationships among sleep, age,
sensory processing, and social skills, therapists’ clinical reasoning could be
enriched. Three associations found are especially clinically meaningful. They are
associations between duration of night waking and proprioception, between
amount of night sleep and vestibular functions, and between social skills and
parasomnias. The relationship between amount of night sleep and duration of
night waking and vestibular-proprioceptive functions could help sensory based
occupational therapists to carefully monitor vestibular-proprioception input in
daytime and sleep in nighttime in children with autism spectrum disorders, in
order to offer appropriate treatments and home programs to both enhance
children’s sensory processing function and increase the quality and quantity of
their sleep. The association between social skills and parasomnias could offer
therapists and parents one more possible reason that social participation in
children with autism spectrum disorders is much more difficult. Therefore, it
might be inappropriate that therapists and parents assume those children respond
with proper social skills in daytime without considering their nighttime sleep.
In addition, for clinical therapists, the difference in duration of night
waking in our finding between groups A and C shows a specially valuable
meaning as being added with the information from the association between
duration of night waking and proprioception. That means as parents answer yes to
the question of whether in general, you think your children have sleep problems,
their children may have more severe proprioceptive function.
Finally, that no association was found in this study between social
participation and sensory processing may draw sensory-based pediatric
90
occupational therapists’ attention because an assumption that autistic children’s
impairments in sensory processing would possibly affect their social participation
might outweigh therapists’ considerations of other factors, such as the ability to
detect and interpret social cues, the flexibility to receive constant changes in
social context, the ability to sympathize and empathize with others, and the
ability to reciprocally speak to others with proper body language. Therefore,
when reasoning about social participation and sensory processing difficulties,
therapists need to be more cautious.

Limitations

Limitations are many. First, participants’ diagnoses were not confirmed by
performing a consistent diagnostic procedure; instead, diagnoses were obtained
from their annual IEP reports stored at PTN and reconfirmed by parents’
responses to question 4 in the question list of the sleep medical history form.
Consequently, the accuracy of their diagnostic categorizations could be
questioned.
Moreover, sleep patterns are different in children with different diagnoses
(Hoban, 2000; Robinson & Richdale, 2003). In our sample of children with
autism spectrum disorders, ADHD or other neurological disorders such as
epilepsy were not excluded. Therefore, sleep patterns measured in our study
might not represent specifically the features of autism spectrum disorders.
Consequently, generalization of any findings in our study to all autistic children
can not be made with confidence.
91
Other factors, such as IQ (Couturier et al., 2005; Richdale, 1999)), the
severity of autism, excitement and tiredness levels before bed, bedtime routines,
and parents’ concepts of sleep problems (Stores, 2001) may affect sleep patterns.
This study did not measure these factors because children’s IEP reports do not
usually contain these types of information. Additionally no extra IQ test or
autistic diagnosis test was performed.
Although our original plan was to recruit children aged 5 to 12 years, the
age range of our actual sample of children was 5 to 9 year and 4 months, because
of the small sample size and the small age range in our sample, testing whether
children with autism younger than 8 years old have more sleep problems
(Richdale, 1999) could not be performed. Despite this limit, it is remarkable that
our findings show significant associations between age and some sleep problems.
Different cultures have different attitudes toward co-sleeping (Wolf et al.,
1996). However, Co-sleeping is indicated as a problem in a subscale, bedtime
resistance in the CSHQ. It is unknown if culture/ethnicity affects parents’
consideration of co-sleeping as a problem, and if parents’ consideration of this
particular sleep pattern may alter their perceptions of the existence of their
children’s global sleep problems in our study. This is definitely an interesting
topic for future study.
Finally, because a clinical sample is used, interpretations of the results from
the clinical sample to community samples may not be appropriate. Future studies
including community samples would increase the confidence of generalization.

92
Suggestions for Future Studies

Several lines of studies are suggested. First, similar studies with
increasing sample size would offer enough data that might be statistically
meaningfully analyzed with regression procedures to find possible
interrelationships and predictors among measures. In addition, recruiting a
non-autistic control group would also assist to find comparisons not only on the
existence of sleep problems in the autistic group, but also on the difference of
sleep patterns between different populations. Recruiting both clinical samples and
community samples might uncover the differences in their sleep, social, and
sensory processing patterns in different environments.
Finally, studies specifically investigating the relationship between sleep
and vestibular-proprioceptive functions are definitely needed. Investigating
cultural differences on co-sleeping in family of autistic children is worthy of
further study. The relationships among social participation, sensory processing,
and other factors, such as the ability to detect and interpret social cues, in children
with autism spectrum also need to be further investigated.
Another line of study about possible unbalance of occupational
orchestration in the families of autistic children with sleep problems is worthy of
attention. Concerns of sleep problems in children with autism spectrum disorders
accumulating parents’ daily stresses and dwindling the whole family’s well being
are indicated in previous studies (Cotton & Richdale, 2006; Honomichl et al.,
2002; Richdale et al., 2000). Since family centered treatment is emphasized in
occupational therapy, data on confirmation of the increased stresses and
93
decreased well being and of outcomes of sensory-based strategies on sleep are
strongly recommended to be collected.
In conclusion, the prevalence and patterns of sleep problems found in this
study proves that sleep problems in children with autism spectrum disorders
require therapists’ attention. The associations among sleep problems, sensory
processing, social participation, and chronological age give valuable information
to therapists to enrich their clinical reasoning.
Sleep, sensory processing, and social participation are three very
complicated factors. Sleep and sensory processing affect not only daytime
behavior, but also the engagement in daily occupation in children with autism
spectrum disorders. Their relationships are even more complex. More studies in
occupational therapy are needed to not only investigate individual factors, but
also accumulate data on their relationships.

94
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Appendix A
Definition of Terms

1. Actigraphy: Actigraphy is a portable device usually attached to participants’
wrists and arms to record their activity levels and, indirectly, sleep
behaviors.
2. Activities of daily living (ADL): ADL refers to activities oriented to care of
individual’s own body, such as bathing dressing, and eating.
3. Autism spectrum disorders (ASD): ASD are a group of disorders sharing
similar symptoms, involving quality of social skills, communication, and
frequency of stereotypical behaviors, also called pervasive developmental
disorders (PDD). ASD include autism disorders, Asperger’s syndrome, and
pervasive developmental disorder not otherwise specified (PDDNOS), Rett’s
syndrome, and childhood disintegrated disorder. In this study, ASD refers to
autistic disorders, Asperger’s syndrome, and PDDNOS.
4. Bedtime resistance: Bedtime resistance refers to feelings and behaviors
happening during bedtime, such as fear to sleep alone, sleeping in others’
bed, parent co-sleeping, and struggling at bedtime
5. Circadian sleep rhythm: Circadian sleep rhythm is a biological time clock. It
regulates the timing and duration of the wake-sleep cycle. Physiologically,
this factor can be seen as a wake drive.
6. Confounders: Confounders refer to factors whose own effects distort
associations between dependent variables and independent variables.

104
7. Continuous performance test (CPT): CPT is used for measuring sustained
visual attention. Participants are required to respond to a certain image as
soon as possible, presented on a screen.
8. Declarative learning: Declarative learning is a “what” learning involving
fact-based information and requiring few exposures to the new information.
9. Disoriented awakening: Disoriented awakening is one of the 5 factors:
expressive sleep disorders, sensitivity to environment, disoriented
awakening, sleep facilitator, and apnea/ bruxism, categorized in the BEDS.
Sleep problem behavior in this factor includes being sluggish or confused
when waking.
10. Dyssomnias: Dyssomnias refers to difficulties in initiating and maintaining
sleep at night and problems with excessive sleepiness at day.
11. Effect modifiers: Effect modifiers are factors that associations between other
factors depend upon.
12. Executive functions (EF): Executive functions are defined as a cognitive
construct for goal-oriented and future-oriented behaviors and includes
“planning, inhibition of predominant responses, flexibility, organized search,
self-monitoring, and the use of working memory”.
13. Explicit learning: Explicit learning is the learning in which learners are
intentionally aware of what they learn.

105
14. Expressive sleep disorders: Expressive sleep disorders are one of the 5
factors: expressive sleep disorders, sensitivity to environment, disoriented
awakening, sleep facilitator, and apnea/ bruxism, categorized in the BEDS.
Sleep problem behavior in this factor includes nightmare type disturbances
such as screaming, night walking, and acting out dreams.
15. Homeostatic: Homeostatic is a sleep drive which gradually increases as
night sleeping approaches. It modulates the depth and length of sleep.
16. Implicit learning: Implicit learning is the learning in which learners have
little awareness of learned new skills.
17. Interaction: Interaction refers to a condition where the relationship of a study
variable of interest and an effect modifier is different with the levels of the
effect modifier.
18. Irregular sleep-wake schedule: Irregular sleep-wake schedule refers to
frequent transitions between light sleep stage and deep sleep stages.
19. Light-off time: Light-off time refers to the time parents or children turn off
the light when going to bed. Sleep onset time is the time sleep starts.
20. Night arousal: Night arousal refers to sleep termination during the night.
21. Number of REM activity: Number of REM activity is the number of rapid
eye movements.
22. Number of REM cycle: Number of REM cycle refers to the number of REM
periods followed by at least 15 minutes non-REM sleep.
23. Non-REM density: Non-REM density refers to the density of eye
movements during non-REM sleep.

106
24. Parasonmias: Parasonmias refer to undesirable automatic motor phenomena
during sleep, such as sleepwalking and sleep terrors.
25. Phasic inhibition index: Phasic inhibition index is the ratio of the number of
chin muscle activities (twitches) for more than 2.0s and total number of
muscle activities.
26. Polysomnography: A polysomnogram contains electroencephalogram (EEG),
electromyogram (EMG), and electroocculogram (EOG) to record brain
electric activity, eye movements, and muscle activation in sleep.
27. Procedural learning: Procedural learning, categorized in non-declarative
learning, is a “how” learning, such as learning an action, a habit, or a skill.
Procedural motor learning often requires more practice and more motor
repetition then declarative learning.
28. REM density: REM density refers to the density of eye movements during
REM sleep.
29. Sensory processing: Sensory processing is a fundamental function for a
person to be able to manage and organize sensory information to
appropriately adapt into social, cultural, spatial, and temporal environments.
30. Sensitive to environment: Sensitive to environment is one of the 5 factors:
expressive sleep disorders, sensitivity to environment, disoriented
awakening, sleep facilitator, and apnea/ bruxism, categorized in the BEDS.
Sleep problem behavior in this factor includes sleeping in parents’ bed and
sensitivity to light or sounds.
31. Sleep: Sleep is a period in a 24 hour sleep-wake rhythm. In this period,
patterns of physical activity and neurobiological activity change.
107
32. Sleep anxiety: Sleep anxiety refers to being afraid of sleeping alone or in the
dark, parent co-sleeping, and having trouble sleeping away from home.
33. Sleep architecture: Sleep architecture refers to the progression of the entire
sleep.
34. Sleep cycle: A sleep cycle refers to a period of a rapid eye movement (REM)
sleep and non rapid eye movement (NREM) sleep. A night of sleep contains
repeated sleep cycles.
35. Sleep facilitator: Sleep facilitator is one of the 5 factors: expressive sleep
disorders, sensitivity to environment, disoriented awakening, sleep facilitator,
and apnea/ bruxism, categorized in the BEDS. This factor includes
medicines and pacifiers.
36. Sleep hygiene: Sleep hygiene refers to sleep routines or habits that initiate
sleep onset and help sleep maintenance.
37. Sleep latency: Sleep latency, also called sleep onset delay or sleep onset
latency, is defined as the period of time from when a child is in bed to when
the child falls asleep.
38. Sleep offset: Sleep offset is the time sleep ends.
39. Sleep percent: Sleep percent is the percentage of true sleep time within total
sleep duration.
40. Sleep problems: A sleep problem is a sleep pattern that interferes with sleep
architecture and interrupts parents’ sleep.
41. Sleep quality: Sleep quality is the satisfaction that people have about their
sleep.

108
42. Sleep stages: Sleep stages refer to the 4 sleep stages during the NREM sleep
state.
43. Sleep states: Sleep states mainly refer to REM sleep and NREM sleep.
44. Sleep time 1/3: Sleep time 1/3 refers to the first third period of true sleep.
45. Sleep time 2/3: Sleep time 2/3 refers to the second third period of true sleep.
46. Symbol-digit substitution (SDS): SDS is a test that requires participants to
match symbol and digit on a screen, based on 6 symbol-digit pairs, shown
on the top of a screen.
47. The R index: The R index refers to the ratio of high frequency REM and low
frequency REM.
48. The Sleep efficiency index: The Sleep efficiency index refers to the index of
true sleep time divided by total time in bed.
49. The Tonic inhibition index: The Tonic inhibition index is the ratio between
the number of chin muscle activities (twitches) for less then 0.5s and that for
more than 2.0s.
50. Time in bed: Time in bed refers to a period when a person is in bed.
51. Total night sleep: Total night sleep, sometimes also called sleep period time,
or sleep duration, refers to the period of time from sleep onset to sleep
offset.
52. True sleep period: True sleep period, sometimes also called total sleep time,
refers to the total night sleep minus the duration of night waking.
53. True sleep time: True sleep time is the time from sleep onset to sleep offset
minus the duration of night waking.

109
54. Two-process sleep model in humans: Two-processing model of sleep is a
model containing two processes: homeostatic and circadian sleep rhythm, to
explain the underlying mechanisms of 24 hour sleep-wake circadian in
humans.
55. Undifferentiated sleep: Undifferentiated sleep refers to the sleep features
presenting both REM and non REM sleep elements in a 30 second epoch.
56. Wake %: Wake % refers to the percentage of night waking.

110
Appendix B
Flyer

An Invitation to Participate
In an Important Study

Dear Parents or Caregivers,

I am conducting a study about sleep problems, sensory processing
difficulties, and social participation in children with autism spectrum
disorders.
I am a master student in the Department of Occupational Science and
Occupational Therapy at USC. If you have children who are 5-12 years old and
who have a diagnosis of autism spectrum disorder, I would like you to
participate in this study. This study will be at PTN. You may obtain more details
of this study in an information packet that includes information about your
rights of participation. This packet is on the front desk at PTN. If you are
willing to participate, please contact me at the phone numbers below or leave
your information in the envelope in the information packet. I will contact you and
request that you sign an informed consent form and fill out three survey forms:
the Children’s Sleep Habit Questionnaire, a sleep medical history form, and the
Sensory Processing Measure.
If you are interested in participation, please contact me:
Day phone #: 310-328-0276 exe 313 Night phone #: 626-534-3301
Thank you very much for your attention.
Chia-Chen Wu
111
Appendix C
Informed consent

STUDY INFORMATION FOR PARENTS

TITLE OF STUDY: SLEEP PROBLEMS, SENSORY PROCESSING
DIFFICULTIES, AND SOCIAL PARTICIPATION IN CHILDREN WITH
AUTISM SPECTRUM DISORDERS
PRINCIPAL INVESTIGATOR: CHIA-CHEN WU

RESEARCH COORDINATOR: CHIA-CHEN WU

TELEPHONE NUMBER: (626) 534-3301

CO-PRINCIPAL INVESTIGATOR: L. Diane Parham, Ph.D., OTR, FAOTA

TELEPHONE NUMBER: (323) 442-2879

DEPARTMENT: OCCUPATIONAL SCIENCE AND OCCUPATIONAL
THERAPY
SCHOOL: UNIVERSITY OF SOUTHERN CALIFORNIA
24-HOUR TELEPHONE NUMBER: (626) 534-3301
PURPOSE OF THE STUDY
The purpose of this study is to better understand sleep problems in children with
autism spectrum disorders, and whether these problems are associated with social
participation and sensory processing difficulties. We will gather information on
about 60 children in this study using survey forms that you, the parent will fill
out.

PROCEDURE:
If you decide to participate, we will introduce the details of the study and your
rights of participating in it and then request that you sign this informed consent.
After you sign the informed consent, we will also ask you to fill out the 3 survey
forms that are enclosed in this packet: the Child’s Sleep Habit Questionnaire
(CSHQ), the Sensory Processing Measure (SPM): Home Form-R, and a brief
sleep medical history form. If you have previously filled out the SPM: Home
Form-R at PTN, then we will not ask you to fill it out again. We will request your
therapist to release the one you have filled out to us in order to copy it to include
in this research study.
112
When you are finished, please return the forms to the research coordinator along
with the informed consent in the packet in which they arrived. The informed
consent will be copied for you immediately. Your child will not be examined or
observed by the researchers in any way as part of this study.

In order to make sure that the identifying information about you and your child
are strictly protected in this study, a study identification number will be assigned
on the packet right after you finish filling out the forms. The study identification
number will also be assigned on the top of each copied form after the original
forms are copied. Other identifying information on the copied forms such as
names, address, or phone numbers will be blacked out. The original forms will be
put back to your child’s record in the files at PTN. The copied forms with the
study identification numbers will be used in the study. They will be stored in a
locked drawer. Only the research coordinator will be allowed to access it. Your
child’s gender, age, and diagnosis will be obtained from the brief sleep medical
history form. At the end, the researcher coordinator will enter the study
identification numbers, your child’s gender, age, diagnosis, and your responses to
the survey forms into a computer for statistical analysis. After the data are entered
into the computer, all of the copied forms will be destroyed. Only the research
coordinator will be allowed to access the computer.

RISKS:
Your child will not be examined or observed by the researchers in any way as part
of this study. However, you may feel inconvenienced by spending the time to
read and complete the survey forms. Some of the questions may make you feel
uneasy or embarrassed. You can choose to skip or stop answering the questions
that make you uncomfortable.

BENEFITS:
You, and your child may receive no direct benefit from his or her
participation in this study. However, your participation in this study will help
us learn more about children with autism spectrum disorders and their
families to obtain more effective and helpful intervention.

WHAT OTHER OPTIONS ARE THERE?
Your alternative would be to not participate in this study.

WILL YOUR INFORMATION BE KEPT PRIVATE?
As noted earlier, the original completed forms will be stored in your child’s
record at PTN. Only PTN staff is allowed to access them. The copied forms and
the packet with study identification numbers will be stored in a locked drawer.
Only the research coordinator will be allowed to access it. Other identifying
information on the copied forms, such as address or names will be blacked out in
113
order to strictly maintain confidentiality. After all of the data are entered into the
research coordinator’s computer, all copied forms will be destroyed. The
information from this study may be published in scientific journals or presented
at scientific meetings, but your child’s identity will not be revealed.

WHAT ARE THE COSTS?
There is no cost to you to participate in this study.

ARE THERE ANY PAYMENTS TO YOU FOR TAKING PART IN THE
STUDY?
There are no payments to you for taking part in this study.

WHAT HAPPENS IF YOU GET INJURED OR NEED EMERGENCY
CARE?
If an injury occurs to you or your child during the study, the financial responsibility for medical
care will be yours.

WILL YOU RECEIVE INFORMATION ABOUT THIS STUDY?
When filling out the forms, if you have any questions, you may ask the research
coordinator freely. If you are interested in the results and conclusion of this study,
please contact the research coordinator.

UNDER WHAT CIRCUMSTANCES CAN YOUR PARTICIPATION BE
TERMINATED?
At any time, if you want to withdraw your child’s participation in this study,
please inform your therapists, and the questionnaires you filled out will not be
used in this study.

WHAT ARE YOUR RIGHTS AS A PARTICIPANT, AND WHAT WILL
HAPPEN IF YOU DECIDE NOT TO PARTICIPATE?
Your participation in this study is voluntary. Your decision whether or not to
participate will not interfere with your child’s right to health care or other
services to which you or your child is otherwise entitled. You and your child are
not waiving any legal claims or rights because of participation in this study. If
you do decide to permit your child to participate, you are free to withdraw your
permission and discontinue your child’s participation at any time.

ARE THERE ANY POTENTIAL CONFLICTS OF INTEREST?
There are no any potential conflicts of interest in this study.

114
WHOM DO YOU CALL IF YOU HAVE QUESTIONS OR CONCERNS?
If you have questions and concerns regarding your child’s participation, or if you feel your child
has been injured as a result of his or her participation, you may contact the Principal Investigator,
Chia-Chen Wu at (626) 534-3301. If you have any questions regarding your child’s rights as a
study subject, you may contact the Institutional Review Board Office at (323) 223-2340.

AGREEMENT:
I have read (or someone has read to me) the information provided above. I have
been given a chance to ask questions. All my questions were answered. I have
decided to sign this form in order to take part in this study.

Name of Parents or Caregivers Signature Date Signed
I have personally explained the research to the parents or caregivers and
answered all questions. I believe that he/she understands the information
described in this informed consent and freely consents to participate.

Name of Investigator

Signature Date Signed
115
Appendix D
Sleep Medical History From

Dear parents:
There are some sleep-related questions that we will like to ask. Part one is
asking about your child; part two about you. These questions can help us make
this study more informative. Thank you very much for answering them.

Part one

1. What is your Child’s age today? _____________________

2. Child’s gender: _____ male ____ female

3. Who filled out this form? ____________________

4. Child’s primary diagnosis? _____________________________
Does your child take any medicine because of his/her diagnosis?
______________________________________________________

5. Has your child been diagnosed with a sleep disorder? If so, what kind?
_______________________________________________________
If yes, does he/she take medicine for sleep disorders? What medicine?
_______________________________________________________

6. In general, do you think your child has sleep problems? ____________

Part two

1. Do you or your partner or other adults in the house have sleep problems?
_________ If yes, what are they? (circle all that apply)
muscle twitches sleep apnea
narcolepsy insomnia
sleep walking others________________________

Thank you very much for helping us understand your child’s sleep.

116
Appendix E
Child’s Sleep Habits Questionnaire
117
118
119
Appendix F
Data Collection Tables
Table 1. Demographic characteristics
Subjects Age (month) Gender Primary Diagnoses Race
120
Table 2a. Sleep characteristics
Sub PDS M for PD Dx of sleep Medicine for sleep Parents’ sleep Bedtime WUtime Amount of NS Duration of NW
Sub: Subject; PDS: Parental description of their children’s sleep; M for PD: Medicine for Primary diagnoses; Dx of sleep: Diagnosis of sleep
disorders; WUtime: Wake-up time; Amount of NS: Amount of night sleep; Duration of NW: Duration of night waking.
121
Table 2b. Sleep characteristics
Sub CSHQT TotalG41 BR Sleep O Sleep D Sleep A NW Parasomnias Sleep B Daytime sleepness
Sub: Subject; CSHQT: CSHQ total score; TotalG41: CSHQ total scoreG41; BR: Bedtime resistance; Sleep O: Sleep onset delay; Sleep D:
Sleep duraiton; Sleep A: Sleep anxiety; NW: Night waking; Sleep B: Sleep breathing;
122
Table 3. Sensory porcessing
Sub SPMsocial SPMsensory vision hearing touch tastesmell body balance ideation
Sub: Subject

Abstract (if available)

Abstract The aim of this pilot study is to investigate the prevalence and patterns of sleep problems in a clinical sample of children aged from 5 to 9 years and 4 months with autism spectrum disorders, and to explore currently unclear associations among sleep problems, sensory processing difficulties, social participation, and chronological age. Surveys including the Child's Sleep Habit Questionnaire (CSHQ), the Sensory Processing Measure Home Form-R (SPM Home Form-R), and a researcher-generated sleep medical history form were given to parents of participants during their visits in a sensory-based occupational therapy program in a private clinic. Thirty three children with a mean age of 6 years and 6 months were sampled. Seventy eight percent of children had sleep problems determined with the CSHQ cutoff score. Sleep patterns in children for whom sleep problems were consistently indicated both on CSHQ total score (greater than or equal to 41) and parent responses on the sleep medical form were more bedtime resistance, less overall sleep duration, and frequent night waking. Chronological age was positively significantly associated with overall sensory functions, but negatively significantly associated with overall sleep problems, night waking, and daytime sleepiness. Moreover, the longer the children slept at night, the better their vestibular functions were. The longer duration that children woke at night, the worse their proprioceptive function was. The more severe parasomnias the children had, the worse their social skills were. These findings not only affirm sleep is related to daily behavior and further to the engagement in occupations in this particular population, but also indicate compelling clinical implications. Further studies are strongly recommended.

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Asset Metadata

Creator Wu, Chia-Chen (author)

Core Title Sleep problems, sensory difficulties, and social participation in children with autism spectrum disorders

School Independent Health Professions

Degree Master of Arts / Master of Public Administration

Degree Program Occupational Therapy

Publication Date 04/10/2007

Defense Date 12/14/2006

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag autism spectrum disorders,OAI-PMH Harvest,sensory difficulties,sleep problems,Social participation

Language English

Advisor Parham, L. Diane (committee chair), Clark, Florence A. (committee member), Neville-Jan, Ann (committee member), Wincor, Michael Z. (committee member)

Creator Email wuchiach@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-m368

Unique identifier UC1324723

Identifier etd-Wu-20070410 (filename),usctheses-m40 (legacy collection record id),usctheses-c127-326062 (legacy record id),usctheses-m368 (legacy record id)

Legacy Identifier etd-Wu-20070410.pdf

Dmrecord 326062

Document Type Thesis

Rights Wu, Chia-Chen

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Repository Name Libraries, University of Southern California

Repository Location Los Angeles, California

Repository Email cisadmin@lib.usc.edu