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This study compared parent-reported sleep characteristics in 2- to 5-year-old children with autism spectrum disorders (ASD) to children with other developmental delays (DD) and typical development (TD). We included 529 children (303 ASD [167 males], 63 DD [46 males], and 163 TD [134 males]) enrolled in the CHARGE study, an ongoing population-based case–control study. The mean age of participants was 3.6 years (standard deviation, 0.8 years). ASD diagnosis was confirmed with Autism Diagnostic Interview-Revised (ADI-R) and Autism Diagnostic Observation Schedules (ADOS). Cognitive and adaptive functioning was assessed using Mullen Scales of Early Learning (MSEL) and Vineland Adaptive Behavior Scales (VABS), respectively. Demographic, medical and sleep history information were ascertained from California birth records, telephone interview, medical assessments at clinic visit, and parent-administered questionnaires. Fifty-three percent of children with ASD had at least one frequent sleep problem, followed by 46% of children with DD, and 32% of the TD group (P < 0.0001). Exploratory factor analyses of sleep history data yielded two factors: sleep onset problems and night waking. Children with ASD had marginally higher sleep onset factor scores and significantly higher night waking factor scores compared with the TD group. Factor scores for children with DD were intermediate between the ASD and TD groups. Cognitive or adaptive development did not predict severity of sleep problems in the ASD group.
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Sleep problems are commonly reported by parents of young children. Approximately 25% of typically developing preschool-aged children have sleep problems pertaining to bedtime resistance, sleep onset delays, and night awakenings (Armstrong et al., 1994; Jenkins et al., 1984; Johnson, 1991; Scher et al., 1995). Other less common sleep disturbances that concern parents include night terrors or nightmares and repetitive rhythmic behaviors, which manifest during the toddler-preschool period in some children (Anders et al., 2000). Finally, 1–3% of children experience sleep-disordered breathing (Ali et al., 1993; Gislason and Benediktsdottir, 1995), a medical condition that also contributes to a reduced quality of sleep. Sleep problems have been broadly classified into three major categories (American Academy of Sleep Medicine., 2001; American Psychiatric Association., 1994): (1) dyssomnias include sleep onset delays and night awakenings, (2) parasomnias include behaviors involving motor and autonomic activation, which intrude on sleep (e.g. night terrors, nightmares, repetitive rhythmic behaviors), and (3) sleep disorders secondary to a physical illness or another psychological disorder. The extant literature has focused primarily on the presence of dyssomnias in both typically developing children as well as clinical samples (Malow, 2004; Sadeh et al., 2002; Wiggs and Stores, 2001).
Autism spectrum disorders (ASD) are pervasive developmental disorders characterized by deficits in social interaction, language development and communication, as well as restricted and stereotyped behavior patterns or interests. Children with ASD experience similar sleep problem types to those observed in typically developing children, although the existing literature suggests that the prevalence of sleep problems in autism is markedly higher than expected, occurring in 44–83% of school-age children (Richdale, 2001). Richdale and Prior (1995) compared preschool- and school-aged children with ASD to a normative sample and found significantly higher levels of current general sleep difficulties according to parent report (44% versus 27%). Parents of autistic children commonly express that their children resist going to bed at an appropriate time (Couturier et al., 2005; Wiggs and Stores, 2004), have difficulties in initiating sleep (Allik et al., 2006b; Couturier et al., 2005; Gail Williams et al., 2004; Honomichl et al., 2002; Patzold et al., 1998; Richdale and Prior, 1995; Wiggs and Stores, 2004), and exhibit nighttime (Allik et al., 2006b; Gail Williams et al., 2004; Honomichl et al., 2002; Patzold et al., 1998; Richdale and Prior, 1995; Schreck and Mulick, 2000; Wiggs and Stores, 2004), and early morning waking (Hering et al., 1999; Patzold et al., 1998; Polimeni et al., 2005; Richdale and Prior, 1995).
There is a bidirectional impact between sleep problems and child development. Sleep disturbances increase the parenting burden and family stress (Doo and Wing, 2006; Mindell and Durand, 1993; Polimeni et al., 2005; Sadeh et al., 2002; Wiggs and Stores, 1998). Recently, in a large population-based study, mothers of typically developing preschoolers with a parent-reported sleep problem also endorsed poor general health (Martin et al., 2007). Family stress was associated with poorer sleep quality in school-aged children with typical development and in children with developmental disabilities (El-Sheikh et al., 2006; Wiggs and Stores, 1998).
Other results indicate that parental hassle intensity is associated with sleep problems in children with autism (Richdale et al., 2000). Additionally, there is accumulating evidence for a relationship between sleep and developmental functioning in children (Sadeh et al., 2002; Wolfson and Carskadon, 1998). Disturbed sleep in children has been associated with cognitive, verbal and attention impairments (Fallone et al., 2005; Gozal, 1998; Quine, 1991; Randazzo et al., 1998), self-help and daytime behavior problems (Allik et al., 2006a; Quine, 1991) including injury-prone behavior (Owens et al., 2005). Daytime dysfunction due to disturbed sleep patterns may be especially taxing for children with neurodevelopmental disorders such as ASD, who already have difficulties in social interaction and communication.
Most research on sleep problems in children has used subjective measures such as sleep diaries and parent-reported questionnaires. Although biases are introduced when utilizing this method, parent reports remain an established measure of sleep behavior in children. Honomichl et al. (2002) found that children whose parents reported a sleep problem, in contrast to those who did not, consistently displayed more delayed sleep onsets and greater sleep fragmentation, which was reflected in subscale scores of the Children’s Sleep Habits Questionnaire (CSHQ; Owens et al., 2000), a validated measure of sleep problems, and sleep diaries. Parents may be unaware of certain sleep behaviors, and thus, underreport them if their child does not alert them in any way. Several studies have demonstrated parental underreporting of sleep problems using objective measures (e.g. actigraphy, videosomnography) (Allik et al., 2006b; Minde et al., 1993; Sadeh, 1996; Sadeh et al., 1991), although Hering et al. (1999) found that parental reports of sleep problems were overstated when compared to actigraphic recordings. In general, parent reports of their children’s sleep problems appear to be a conservative but reliable measure (Minde et al., 1993).
The underlying cause of poor sleep may include behavioral factors, medical factors or an interaction of both factors. Medical conditions that can impact sleep patterns in children include the presence of seizures, cerebral palsy, sleep disordered breathing, and pharmacological side effects (Newman et al., 2006; Owens et al., 1998). A recent report indicated a significant association between the presence of insomnia and parasomnias with gastrointestinal symptoms as reported by parents (Liu et al., 2006). Children with ASD in particular may be prescribed medications, e.g. respiridone, that may have a disruptive impact on sleep (Mindell and Owens, 2003).
Research investigating sleep patterns in children with ASD has documented parental concerns, although shortcomings in the existing literature include small sample sizes, inconsistent diagnostic definitions, and convenience samples of controls. None of the studies to date have used a population-based sample for comparison; thus limiting both the validity and the generalizability of their findings. The aim of this report was to compare parent-reported sleep characteristics in young children with ASD between 2 and 5 years of age to typically developing children of the same age as well as children with other developmental delays (DD) using a large, well-characterized population-based study sample.
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The mean age of children included in the analyses (n = 529) was 3.6 years (SD 0.8); TD children were significantly younger compared with the DD (3.3 years versus 3.6 years, P = 0.04) or the ASD (3.3 years versus 3.7 years, P < 0.0001) groups. Males represented 88% (n = 167) in the ASD group, 73% (n = 46) in the DD group, and 82% (n = 134) in the TD group (P = 0.01). Overall, close to half the children were White, one-third Hispanic, and the remainder of other race/ethnicity (Table 2). Mothers of DD children had the lowest level of education: 27% with college degree, as compared with mothers of ASD (45%, P = 0.01) or of TD (52%, P = 0.001) children (Table 2).
Table 2. Demographic and perinatal characteristics of children with ASD, delayed and typical development*
|Characteristic||ASD (n = 303)||DD (n = 63)||TD (n = 163)|
|Child’s age (years)|
| 3||102||33.7||28||44.5||62||38.1|| |
| 4||108||35.6||21||33.3||41||25.1|| |
| 5||22||7.3||0||0.0||0||0.0|| |
|Sex, % male||267||88.1b||46||73.0bc||134||82.2c||0.01|
| Hispanic||98||32.3||28||44.4||52||31.9|| |
| Other||50||16.5||10||15.9||33||20.2|| |
|Maternal age at birth of child (year)|
| 25–34||187||61.7||39||61.9||93||57.1|| |
| ≥35||80||26.4||11||17.5||39||23.9|| |
|Paternal age at birth of child (year)|
| 25–34||144||48.6||31||51.7||78||48.4|| |
| ≥35||128||43.2||20||33.3||61||37.9|| |
|Mother’s level of education|
| ≤High school||38||12.5b||20||31.7b||33||20.3||<.0001|
| Some college||130||42.9a||26||41.3c||46||28.2ac|| |
| ≥College degree||135||44.6b||17||27.0bc||84||51.5c|| |
|Highest level of education in household|
| ≤High school||24||7.9b||14||22.2b||20||12.3||0.006|
| Some college||97||32.0||25||39.7||52||31.9|| |
| ≥College degree||182||60.1b||24||38.1bc||91||55.8c|| |
|Birth weight (g)|
| ≥2500||281||92.7||55||87.3||154||94.5|| |
|Gestational age (weeks)|
| ≥37||236||87.7||54||91.5||130||87.8|| |
| First born||135||44.6||21||33.3||75||46.0||0.19|
| Second born or later||168||55.4||42||66.7||88||54.0|| |
About one-fifth of children with DD had a history of non-febrile seizures compared with children with ASD (6.6%, P = 0.002) or children with TD (0%, P < 0.0001); the proportion of children with ASD and history of non-febrile seizures was also significantly higher than that of children in the TD group (P < 0.0001, Table 3). Current use of medications and/or dietary supplements was significantly higher in children with ASD (34%) and DD (48%) compared with TD controls (17%; P < 0.0001, P < 0.0001, respectively). Similarly, frequent gastrointestinal symptoms such as gaseousness/bloating, diarrhea and/or constipation were reported more frequently in the ASD (30%) and DD (21%) groups compared with the TD group (5.1%; P < 0.0001, P = 0.0008, respectively, Table 3).
Table 3. Clinical and developmental characteristics of children with ASD, delayed or typical development*
|Characteristic||ASD (n = 303)||DD (n = 63)||TD (n = 163)|
|History of seizures|
| Febrile seizure||18||6.6||2||3.4||3||1.9||0.06|
| Non-febrile seizures||18||6.6b||12||20.7bc||0||0.0c||<0.0001|
| Any seizures||28||10.3||12||20.7c||3||1.9c||<0.0001|
|Current use of medications or supplements for§|
| Allergic disorders||24||8.9||3||5.2||10||6.4||0.48|
| Central nervous system||22||8.1a||11||19.0c||1||0.6ac||<0.0001|
| Endocrine system||1||0.4b||3||5.2b||2||1.3||0.04|
| Gastrointestinal tract||11||4.1||5||8.6c||2||1.3c||0.04|
| Respiratory tract||14||5.2b||10||17.2b||12||7.7||0.01|
| Dietary supplements||46||17.0a||9||15.5c||7||4.5ac||0.0002|
| Any medications/supplements||93||34.3a||28||48.3c||26||16.7ac||<0.0001|
|Current gastrointestinal symptoms|
| Any gastrointestinal symptoms||91||30.4a||13||20.6c||8||5.1ac||<0.0001|
| Cognitive function, ≤ 70||237||79.8ab||60||95.2bc||0||0.0ac||<0.0001|
| Adaptive function, <70||220||73.1a||44||69.8c||0||0.0ac||<0.0001|
| Combined low cognitive/adaptive function||193||65.4a||41||65.1c||0||0.0ac||<0.0001|
| Normal IQ†||39||13.2ab||0||0.0bc||163||100ac||<0.0001|
Overall, 53% of children with ASD and 46% of DD children had at least one sleep problem that was reported as occurring ‘frequently’ or ‘always’ compared with 32% of TD children (P < 0.0001, P < 0.05, respectively, Table 4). In the ASD group, 21% of parents perceived that their child’s sleep problem affected the child’s daily functioning and 23% of parents reported that their child’s sleep problem affected the family’s daily functioning. Similarly, 20% of children in the DD group had a sleep problem that affected their daily functioning and 21% of children in this group had a sleep problem that affected their family’s daily functioning. In contrast, 1.2% of children in the TD group had a sleep problem that affected their daily functioning and 2.5% had sleep problems that affected their family’s daily functioning (AU versus TD, P < 0.0001; DD versus TD, P < 0.0001, Table 4). The majority of children slept between 10 and 12 h in a 24-h period, but TD children tended to get one additional hour of sleep compared with children with ASD (median: 11 versus 12 h, P < 0.0001).
Table 4. Sleep problems of children with ASD, delayed or typical development*
| ||ASD (n = 303)|| DD (n = 63)|| TD (n = 163)|
|Summarized sleep patterns|
| Any frequent sleep problems||159||52.5a||29||46.0c||52||31.9ac||<0.0001|
| Any frequent sleep onset problems||155||51.2a||29||46.0c||52||31.9ac||0.0003|
| Any frequent night waking problems||30||9.9a||2||3.2||3||1.8a||0.0007|
| Does sleep problem affect child’s daily functioning||61||20.7a||12||19.7c||2||1.2ac||<0.0001|
| Does sleep problem affect family’s daily functioning||69||23.1a||13||21.3c||4||2.5ac||<0.0001|
|Factor 1. Sleep onset problems|
| Has trouble falling asleep||74||24.4a||12||19.0c||14||8.6||<0.0001|
| Goes to bed at different times||67||22.1a||20||31.7c||21||12.9ac||0.0035|
| Resists going to bed at night||66||21.8||10||15.9||26||15.9||0.23|
| Sleeps better in places other than his/her bed||53||17.5a||11||17.5||14||8.6a||0.02|
| Sleeps less than children his/her own age||46||15.2a||6||9.5||8||4.9a||0.0018|
| Throws tantrums at bedtime||30||9.9a||6||9.5c||5||3.1ac||0.01|
| Gets less than 6 h sleep in a 24 h period||7||2.3a||1||1.6||0||0.0a||<0.05|
|Factor 2. Night waking|
| Wakes up screaming during the night||20||6.6a||1||1.6||1||0.6a||0.0014|
| Screams during the second half of the night||19||6.3a||1||1.6||1||0.6a||0.0022|
| Has nightmares||13||4.3a||1||1.6||1||0.6a||0.03|
| Wakes up screaming approximately 2 h after going to sleep||8||2.6||1||1.6||3||1.8||0.79|
Exploratory factor analysis
The exploratory factor analysis produced two factors involving 11 sleep history items which were retained for further analysis. The factors were: Sleep Onset Problems [7 items] and Night Waking [4 items] (Table 4). Internal consistency (i.e., Cronbach α, an index of reliability for a set of items that indicates the extent to which items measure the same characteristic) was calculated for each factor and was within conventional levels (Sleep Onset Problems α = 0.79 and Night Waking α = 0.81). ‘Has trouble falling asleep’ was the most common item in factor 1, sleep onset problems, reported as occurring frequently in 24% of children with ASD, 19% of DDs, and 9% of TDs (P < 0.0001, Table 4). In factor 2, night waking, parents of 7% of ASDs, 2% of DDs, and 1% of TDs indicated the item ‘Wakes up screaming during the night’ as occurring frequently (P = 0.0014, Table 4).
The item scores were evaluated for a possible cut-off total associated with significantly elevated, or ‘high’, factor scores (defined as a factor score 1 standard deviation or higher above the mean). The sum of item scores that corresponded to ‘high’ factor scores in all children were selected as cut-offs. On factor 1, sleep onset problems, the maximum sum of items was 28 points, and 15 or more item score points corresponded to a ‘high’ factor score. Overall, 53 (10%) participants met this cut-off of 15 or more points on sleep onset items. The largest proportion of elevated sleep onset problems was in those with ASD (n = 41, 13%) followed by participants with DD (n = 6, 9.5%) and TD (n = 6, 3.7%). On factor 2, night waking, a sum of items equal to 7 or more points (out of 16 points total) corresponded to a ‘high’ factor score, and 8.5% of participants (n = 45) met this point cut-off. The ASD group had the highest proportion of participants with elevated item scores (n = 34, 11%), followed by 6.3% participants with DD (n = 4), and 4.3% with TD (n = 7).
Multivariate linear regression analyses
The primary set of regression analyses focused on comparing children with ASD, DD and TD on (1) sleep onset factor scores, (2) night waking factor scores, and (3) hours of sleep in a 24-h period with adjustment for covariates. In a model adjusted for child’s sex, age, current use of allergy, CNS and respiratory medications, and frequent gastrointestinal symptoms, children with ASD had higher sleep onset factor scores compared with TD children, although the difference was of borderline statistical significance (β [coefficient] = 0.177, SE [standard error] = 0.091, P = 0.05). Higher sleep onset scores, indicating more sleep onset problems, were associated with CNS medication use (β = 0.366, SE = 0.153, P = 0.02) and frequent gastrointestinal symptoms (β = 0.385, SE = 0.099, P = 0.0001) in all groups whereas respiratory medication use was significantly associated with lower sleep onset factor scores (β = −0.370, SE = 0.152, P = 0.01). Children with DD did not differ significantly from the ASD or TD groups on sleep onset factor scores. Night waking factor scores were significantly elevated in the ASD group compared with TD children (β = 0.294, SE = 0.090, P = 0.001) after adjusting for child’s sex, age, allergy and respiratory medications, and birth order. Factor scores significantly decreased by 0.16 for each year increase in a child’s age (β = −0.164, SE = 0.050, P = 0.001). Use of respiratory medications was also significantly associated with lower night waking factor scores (β = −0.347, SE = 0.159, P = 0.03). For parent report of average sleep duration in a 24 h period, a model adjusted for child’s age, sex, mother’s education level, and use of respiratory medications suggested that children with ASD tended to sleep about half an hour less than TD children (β = −0.473, SE = 0.156, P = 0.003). Mother’s education and child’s use of respiratory medications were also strong predictors of increased sleep duration (β = 0.431, SE = 0.140, P = 0.002; β = 0.607, SE = 0.265, P = 0.02, respectively) in all children.
As cognitive and adaptive development appeared to play a role in the frequency of sleep problems, we examined the entire study sample for associations between cognitive and adaptive scores and sleep onset and night waking factor scores as well as total amount of sleep, adjusted for child’s age and sex. Overall, participants’ higher cognitive and adaptive scores were significantly associated with (1) lower sleep onset factor scores (cognitive: β = −0.049, SE = 0.021, P = 0.02; adaptive: β = −0.080, SE = 0.024, P = 0.0009); (2) lower night waking factor scores (cognitive: β = −0.055, SE = 0.022, P = 0.01; adaptive: β = −0.081, SE = 0.024, P = 0.001); and (3) increase in amount of sleep (cognitive: β = 0.121, SE = 0.036, P = 0.001; adaptive: β = 0.115, SE = 0.042, P = 0.006). However, in secondary analyses of the ASD group alone, sleep disturbances were not associated with cognitive and/or adaptive delays.
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In this population-based study of parent reported sleep problems in preschool children with ASD, DD, and TD, parents in all three groups reported very high rates of sleep concerns. Approximately half of the parents of children with ASD and children with DD reported at least one sleep difficulty, while one-third of the parents of children with TD had similar concerns. These prevalence rates of at least one sleep problem are similar to those reported previously (Cotton and Richdale, 2006; Couturier et al., 2005; Gail Williams et al., 2004; Hering et al., 1999; Liu et al., 2006; Owens et al., 1998; Polimeni et al., 2005; Richdale and Prior, 1995; Wiggs and Stores, 2004). Given that this is the first large sample of children with ASD to be assessed for sleep problems and to be compared with a population-based comparison sample, it is interesting to observe comparable rates.
An exploratory factor analysis of the CHARGE Sleep History yielded two factors indicating two types of sleep problems predominant in this group of young children: problems with sleep onset and with night awakenings. Regression models that adjusted for age, sex and medical factors suggested that children with ASD have a trend towards more problems with sleep onset and have significantly more night awakenings compared to their peers with TD. Children with DD fell between these two groups, with fewer problems reported in both areas than for children with ASD, but more than for typically developing children. Medical factors, such as use of psychoactive medications and gastrointestinal problems, were also associated with reported sleep problems in all children, although in different ways. Psychoactive medications were associated with increased sleep onset difficulties but not night waking. Likewise, frequent gastrointestinal symptoms were related to more problems with sleep onset but not night waking.
The CHARGE Sleep History factor scores were subsequently dichotomized for two groups of participants: one with ‘high’ sleep problems scores, meaning that scores were 1 standard deviation or more above the mean sleep factor score, and another group with ‘low’ scores, meaning less than 1 standard deviation above the mean. Hence, while all of the children that met the item score cut-off had significantly high factor scores, children with elevated factor scores but item scores below the set cut-offs were not considered as having a ‘high’ or severe sleep problem in this set of analyses. Using this conservative definition, our results suggest that while children with ASD are more likely to have high sleep disturbances (13%) compared with children with DD (9%) or TD (5%), all three groups have a lower incidence of more severe sleep disturbance than previously reported (Cotton and Richdale, 2006; Couturier et al., 2005; Polimeni et al., 2005).
In contrast, when we compared a parent report of at least one frequent sleep problem, 52% of children with ASD, 46% of children with DD, and 32% of typically developing children had a current sleep problem. These findings are in the middle of a range of reported rates of sleep problems in children with ASD (44–86%) (Cotton and Richdale, 2006; Couturier et al., 2005; Gail Williams et al., 2004; Hering et al., 1999; Liu et al., 2006; Polimeni et al., 2005; Richdale and Prior, 1995; Wiggs and Stores, 2004). Likewise, our results in children with other developmental disabilities corresponded to those of Cotton and Richdale (2006) who found a prevalence of 44% for current sleep problems in a group of 43 children with intellectual disabilities. The previously reported prevalence of sleep problems in a typically developing sample of children ranged between 11% and 50% (Cotton and Richdale, 2006; Couturier et al., 2005; Owens et al., 1998; Polimeni et al., 2005); our findings were consistent with the mid-range of the reported rates. Direct comparison of the frequency of sleep problems across studies is difficult because of variations in instruments used to ascertain the data on sleep problems or in the definition of sleep problems. Nevertheless, our results approximated previously reported prevalence of sleep problems as reported by parents.
The relationships between cognitive and adaptive development and sleep patterns in young children with ASD have not been previously investigated with such a large sample. In our combined analyses with all diagnostic groups together, lower cognitive and adaptive function was associated with increased difficulties with sleep onset and night awakening, as well as shorter duration of sleep. In studies of children with mild to severe intellectual disabilities of mixed etiologies, more severe levels of intellectual disability were associated with more parent-reported sleep problems, both in terms of sleep onset latency and night waking duration (Didden et al., 2002; Richdale et al., 2000). However, in the ASD group alone, cognitive level and adaptive function did not predict the severity of either type of sleep problem or the duration of sleep. Similar results have been reported previously in a smaller sample (Richdale and Prior, 1995).
The impact of parent-reported sleep problems also differed across the diagnostic groups. Very rarely did parents of children with TD report that their children’s sleep problems affected child or family function, whereas a high percentage of parents from the other groups so reported. These results are consistent with a previous report (Richdale et al., 2000) of the impact of a child’s sleep problem on the family. We found one in five families of children with ASD and with DD reported sleep problems affecting both child and family function.
One limitation of our study is the reliance on parent report. In studies that have compared both parent report of sleep problems and objective actigraphy of sleep patterns in school age children with ASD, parents were accurate reporters of sleep patterns if their child made them aware of their difficulty (e.g. child disturbs the parent when they are awake at night) (Wiggs and Stores, 2004). The results of the current study are similar to other studies of children with ASD that utilized parent report only using the CSHQ (Couturier et al., 2005; Honomichl et al., 2002), although the CHARGE study is the first to examine sleep in a large, well-defined, population-based sample with confirmed ASD cases and population-based controls; thus, we are confident that these findings are less confounded by recruitment bias or diagnostic uncertainty than previously published reports.
Another potential limitation of this study includes the short response format used to describe the type of sleep problems, a 5-point Likert scale. Other questionnaires, such as the CSHQ (Owens et al., 2000), include a number of statements that parents respond to for clarification of the sleep problems noted. However, the rapidity in which the CHARGE Sleep History can be completed (5 min) and the similarity to outcomes using longer questionnaires such as the CSHQ suggest that accurately probing about sleep problems is not time-consuming and the use of a briefer questionnaire is valid and useful.
In summary, this study supports previous research indicating that children with ASD have greater difficulty with sleep onset and night waking than children with DD and TD. This confirmation is notable, given that the study sample was well-defined, population-based, and that we controlled for medical and other factors affecting sleep. Sleep onset and night awakenings are the predominant problem areas, and these problems affect daily functioning of both the child and the families of one in five children with either ASD or developmental delay. Further research related to both etiology of these sleep disturbances as well as effective interventions is warranted.