Children and adolescents with autistic spectrum disorders (ASD) suffer from sleep problems, particularly insomnia, at a higher rate than typically developing children, ranging from 40% to 80%. Sleep problems in ASD might occur as a result of complex interactions between biological, psychological, social/environmental, and family factors, including child rearing practices that are not conducive to good sleep. Interestingly, children with a history of developmental regression have a more disturbed sleep pattern than children without regression. Even though regulation of sleep in children with ASD is still poorly understood, circadian abnormalities in autism might be the result of genetic abnormalities related to melatonin synthesis and melatonin's role in modulating synaptic transmission. Recently a bifurcation of the sleep/wake cycle with increased sensitivity to external noise and short sleep duration causing irregular sleep onset and wake up times has been suggested. Identifying and treating sleep disorders may result not only in improved sleep, but also impact favorably on daytime behavior and family functioning. Several studies have also demonstrated effectiveness of behavioral interventions for sleep onset and maintenance problems in these populations. When behavioral interventions are not effective or lead only to a partial response, pharmacological treatment options should be considered. Studies of melatonin use in children with ASD provide evidence for its effectiveness and safety in the long run. The clinician assessing a child with an ASD should screen carefully for sleep disorders and make referrals as indicated. Copyright 2010 Elsevier B.V. All rights reserved.