The impact of increasing sleep restriction on cortisol and daytime sleepiness in adolescents

► Sleep debt is a widespread phenomenon among adolescents in industrialized societies. ► Sleep restriction impacts relevant health outcomes. ► Objective daytime sleepiness was linearly elevated with increasing sleep restriction. ► No effect of sleep restriction on evening or morning cortisol levels was observed. ► Detrimental effects of sleep restriction might be unmasked under highly stressful living conditions.