Theta Activity at Sleep Onset in Children with Autism Spectrum Disorder

Despite the enormous clinical relevance of disordered sleep to autism spectrum disorder (ASD), to date, few studies have employed objective measures of sleep architecture in ASD. Previous studies have identified an association between slow wave activity in electroencephalography (EEG) at sleep onset and daytime cognitive and affective functioning in other neuropsychiatric disorders. However, it is unknown whether slow wave activity, particularly Theta activity, at sleep onset is present more in ASD and whether it is related to daytime functioning. We used polysomnography (PSG) to investigate the presence of Theta activity at sleep onset in 60 children and adolescents aged 5.6-18.3 years old with ASD and 70 typically developing controls (TD). We performed visual analysis of PSG to identify bursts of theta activity at sleep onset (TASO) and examined its association with cognition, affect, and daytime behavior in children with ASD. TASO was more prevalent in ASD participants (30%) compared to controls (6%). The TASO (+) group scored significantly worse on the affect recognition test with a large effect size (18.6 (8.0) vs. 23.5 (5.5), t = 2.30, p = 0.027, d = 0.75). TASO was not associated with any other cognitive or affective measures; however, there was a trend toward association with worse daytime behavior. Our findings identify TASO as a feature of objective sleep in children with ASD, and provide a potential mechanism underlying previous reports of an association between poor sleep and ASD symptom severity, especially social cognition.