Maternal psychological control has been linked consistently to poorer adjustment for adolescents, however, studies of variability in the association between psychological control and adjustment are rare. Sleep serves crucial bioregulatory functions that promote well-being and protect youths against poor adjustment associated with negative family environments. We hypothesised that the link between maternal psychological control and adolescent maladjustment would be strongest for youths with poorer actigraphy-based sleep. The current study included 245 adolescents (Mage  = 15.79 years, 52.2% girls, 33.1% Black/African American and 66.9% White/European American; 43% at or below the poverty line). Adolescents reported on their mothers' psychological control toward them, as well as their internalising and externalising symptoms (aggressive and rule breaking behaviours). Several sleep variables were derived: minutes, onset time, and variability in each parameter over 1 week. For youths with shorter, less consistent sleep (both mean levels and variability in minutes and onset), maternal psychological control was associated with adjustment difficulties, especially externalising symptoms. This association was not significant for youth obtaining longer, more consistent sleep. The results were most evident for variability in sleep minutes and onset as moderators of effects. The findings suggest that longer and more consistent sleep is an important protective factor in the context of more controlling parenting.