Sleep disorders (SD) are common in autism spectrum disorder (ASD), yet relatively little is known about the potential genetic mechanisms involved in SD and ASD comorbidity. The current study begins to fill this gap with a gene enrichment study that (1) identifies risk genes that contribute to both SD and ASD which implicate circadian entrainment, melatonin synthesis, and several genetic syndromes. An over-representation analysis identified several enriched pathways that suggest dopamine and serotonin synapses as potential shared SD and ASD mechanisms. This overlapping gene set and the highlighted biological pathways may serve as a preliminary stepping-stone for new genetic investigations of SD and ASD comorbidity.