People with SMS, a neurodevelopmental disorder resulting from haploinsufficiency of the RAI1 gene and bearing many similarities to autism spectrum disorder (e.g., speech and language impairment, behavioral inflexibility, motor stereotypies, and other repetitive behavior; [167–169]), exhibit disturbances in sleep and circadian rhythms that are tightly linked to inverted circadian patterns of melatonin secretion [170–175]. The gene discussed is RAI1; the disease is Smith-Magenis syndrome.