The purpose of this review article is to describe the clinical data linking autism with sleep and epilepsy and to discuss the impact of treating sleep disorders in children with autism either with or without coexisting epileptic seizures. Studies are presented to support the view that sleep is abnormal in individuals with autistic spectrum disorders. Epilepsy and sleep have reciprocal relationships, with sleep facilitating seizures and seizures adversely affecting sleep architecture. The hypothesis put forth is that identifying and treating sleep disorders, which are potentially caused by or contributed to by autism, may impact favorably on seizure control and on daytime behavior. The article concludes with some practical suggestions for the evaluation and treatment of sleep disorders in this population of children with autism.