This study aimed to examine sleep problems in children with autism spectrum disorders (ASD), attention-deficit/hyperactivity disorder (ADHD), and epilepsy in clinical settings. We assessed 64 children with ASD, 64 with ADHD, 64 with epilepsy, and 64 typically developing children without any neuropsychiatric disorders by using a sex-and age-matched case-control study design. The parents reported their children's sleep problems. Parents of children with ASD and ADHD reported more current and lifetime sleep problems of their children than parents of children with epilepsy, especially in snoring and restless legs syndrome. Current or lifetime sleep problems did not differ between children with ASD and children with ADHD, or between children with epilepsy and typically developing children. Demographic characteristics and medication status could not fully explain the increased risk of sleep problems in children with ASD and ADHD. Our findings lend evidence to support more sleep problems in children with ASD and ADHD than typically developing children. Our study adds that children with epilepsy do not. These findings emphasize the importance to assess sleep problems in children with neurodevelopmental disorders highly comorbid with ASD or ADHD in clinical practice. (Contains 3 tables.)