State-Dependent Differences in Functional Connectivity in Young Children With Autism Spectrum Disorder

•We used EEG to examine the connectivity in young children in awake, rapid eye movement, and slow wave sleep (SWS) states.•Differences in coherence between the autism group and the other groups were maximal during SWS.•Sleep may be the most sensitive time to measure differences in neuro-development before they are observable in behavior.