An Electroencephalographic Study of Sleep Spindle and Infraslow Oscillation in Children With Autism Spectrum Disorder

We investigated whether sleep microstructures show spatial differences in young children with autism compared with typically developing peers. 32-channel electroencephalography (EEG) during natural sleep after 5-6 h of partial sleep deprivation was recorded from 53 children (26 with autism, 27 typically developing; 1.1-5.1 years). Quantified EEG features included spindle density, frequency, morphology, slow oscillations and the relative power of infraslow oscillations (0.005-0.03 Hz). Clinical associations were examined using the Autism Diagnostic Observation Schedule, the Childhood Autism Rating Scale and the Gesell Developmental Schedules. Children with autism showed greater modulation of spindle frequency by the phase of slow oscillations at a right frontal scalp electrode (F8). An infraslow peak slightly below 0.02 Hz was present in both groups. Although group differences in infraslow power did not remain significant after correction for multiple comparisons, infraslow power correlated positively with autism severity in males, over posterior and temporal regions. These findings indicate that sleep microstructures in early childhood reflect thalamocortical and cortical dysfunction with sex-specific clinical associations.