Although previous studies suggested a relationship between headache and sleep disturbances, polysomnographic findings in children with headache are rarely described. We investigated polysomnographic findings in children with headaches, and correlated them with headache type and severity, body mass index, and medical treatment. Analysis of polysomnographic findings of 90 children with migraine (60), chronic migraine (11), tension headache (6), and nonspecific headache (13) indicated that sleep-disordered breathing was more frequent among children with migraine (56.6%) and nonspecific headache (54%) vs chronic migraine (27%). Tension headache was not associated with sleep-disordered breathing. In the nonspecific headache group, children with sleep-disordered breathing had higher body mass indexes (P = 0.008). Severe migraine and chronic migraine were associated with shorter sleep time, longer sleep latency, and shorter rapid eye movement and slow-wave sleep. Fifty percent of children with tension headache manifested bruxism vs 2.4% of children with nontension headache (odds ratio, 1.95; 95% confidence interval, 1.2-4.34). Our results support an association between migraine and sleep-disordered breathing, and between tension headache and bruxism, in children. Moreover, disrupted sleep architecture with reduced rapid eye movement and slow-wave sleep in severe and chronic migraine headaches may support an intrinsic relationship between sleep and headache disorders.