Adolescents often experience insufficient, inconsistent and poor-quality sleep. Deviant peer affiliation may promote insufficient or inconsistent sleep schedules, and could be an important factor in understanding adolescents' sleep. Furthermore, parenting behaviours have been shown to impact sleep in youth. We examined relations between deviant peer affiliation and sleep in adolescents, and assessed the role of maternal management of peer relationships as a moderator of these associations. A sample of 131 adolescents (M