Sleep architecture is associated with core symptom severity in autism spectrum disorder

Study Objectives: While caregiver-reported sleep disturbances are common in children and adolescents with autism spectrum disorder (['), few studies have measured objective sleep in ASD compared to controls, and their findings are mixed. We investigated (1) differences in sleep architecture, specifically slow-wave sleep (SWS) and rapid eye movement (REM) sleep, between ASD and typically developing controls (TD); and (2) if any observed differences in sleep were associated with core ASD symptoms. Methods: We used ambulatory polysomnography (PSG) in 53 participants with ASD (ages 4-18) and 66 age-matched TD in their home sleeping environment. The primary outcome measures were SWS and REM sleep. Core behavioral ASD symptoms were assessed using the Autism Diagnostic Interview-Revised (ADI-R). Spectral power bands during sleep, and additional behavioral measures, were examined in exploratory analyses. Results: Compared to TD, participants with ASD exhibited a higher SWS ratio and lower REM sleep ratio. Within the ASD group, higher SWS was associated with more severe symptoms on the Restricted, Repetitive, and Stereotyped Behaviors subscale of the ADI-R. No association was observed between REM sleep ratio and any ASD symptom. Conclusions: Increased SWS and reduced REM sleep ratio differentiated ASD from TD. However, only increased SWS was associated with more severe core ASD symptoms. Increased SWS may reflect neuronal immaturity specific to ASD in this age group. These findings may inform the underlying mechanisms of clinical symptoms observed in children and adolescents with ASD.