Objective and subjective sleep characteristics across severity subgroups in children with autism spectrum disorder.

BACKGROUND: Sleep disturbances are common in children with autism spectrum disorder (ASD), yet the relationship between objective sleep characteristics and ASD severity remains unclear. We examined polysomnography-derived and caregiver-reported sleep characteristics in children with ASD and typically developing children (TDC), with additional analyses across ASD severity subgroups. METHODS: We included 111 children aged 3-13 years: 81 with ASD and 30 TDC. Participants underwent home PSG, and second-night PSG data were used for the primary analyses. Caregiver-reported sleep behaviors were assessed with the Children's Sleep Habits Questionnaire. Children with ASD were classified by Childhood Autism Rating Scale scores into mild (M-ASD, n = 36) or moderate-to-severe (MS-ASD, n = 45) subgroups. Group comparisons used age- and sex-adjusted analysis of covariance with correction for multiple comparisons. Exploratory logistic regression and receiver operating characteristic analyses were conducted in the ASD group. RESULTS: Compared with TDC, children with ASD showed poorer sleep continuity, including lower sleep efficiency and longer sleep latency, with greater wake after sleep onset in the primary model. Sleep-architecture differences were not significant after correction. Across severity subgroups, sleep-continuity difficulties were present in both ASD subgroups, whereas increased wake after sleep onset and greater caregiver-reported bedtime difficulties were most evident in MS-ASD. Bedtime resistance, sleep onset delay, and sleep anxiety differed across severity subgroups. Exploratory ASD-only analyses suggested that selected PSG and caregiver-reported variables may provide complementary information for characterizing differences between M-ASD and MS-ASD. CONCLUSIONS: Children with ASD showed poorer sleep continuity than TDC, and children with MS-ASD had more pronounced caregiver-reported bedtime difficulties. Objective and caregiver-reported sleep measures may provide complementary information for characterizing sleep phenotypes across ASD severity.