OBJECTIVE (1) Compare sleep behaviors of children with autism spectrum disorders (ASD) with sleep behaviors of typically developing (TD) children using the Children's Sleep Habits Questionnaire (CSHQ); (2) compare sleep quality--defined as mean activity, sleep latency, number of awakenings, sleep efficiency and total sleep time--of the cohort of children with ASD and TD, as measured by 10 nights of actigraphy; and (3) estimate the prevalence of sleep disturbances in the ASD and TD cohorts. METHODS Descriptive cross-sectional study. METHODS The Children's Hospital of Philadelphia. METHODS Randomly selected children from the Regional Autism Center. The ASD cohort of 59 children, aged 4 to 10 years, (26 with autism, 21 with pervasive developmental disorder-not otherwise specified [PDD-NOS], and 12 with Asperger disorder) were compared with 40 TD control subjects. RESULTS The CSHQ, sleep diaries, and 10 nights of actigraphy using the Sadeh algorithm of children with ASD and TD control subjects were compared. CSHQ showed 66.1% of parents of children with ASD (62.5% autism, 76.2% PDD-NOS, 58.3% Asperger disorder) and 45% of parents of the control subjects reported that their children had sleep problems. Actigraphic data showed that 66.7% of children with ASD (75% autism, 52.4% PDD-NOS, 75% Asperger disorder) and 45.9% of the control subjects had disturbed sleep. CONCLUSIONS The prevalence estimate of 45% for mild sleep disturbances in the TD cohort highlights pediatric sleep debt as a public health problem of concern. The prevalence estimate of 66% for moderate sleep disturbances in the ASD cohort underscores the significant sleep problems that the families of these children face. The predominant sleep disorders in the ASD cohort were behavioral insomnia sleep-onset type and insomnia due to PDD.