There are several converging reasons to focus on sleep regulation in relation to healthy adolescent development: (a) Sleep appears to be particularly important during periods of brain maturation; (b) there are substantial biological and psychosocial changes in sleep and circadian regulation exist across pubertal development; (c) interactions between physical and psychosocial domains can lead to dramatic alterations in sleep patterns and habits during adolescence; (d) increasing evidence that many adolescents frequently obtain insufficient sleep exists; (e) there is mounting evidence that sleep deprivation has its greatest negative effects on the control of behavior, emotion, and attention, a regulatory interface that is critical in the development of social and academic competence, and psychiatric disorders; (f) the most obvious direct health consequences of insufficient sleep are high-risk behaviors associated with substance abuse and automobile accidents; (g) substantial evidence for bidirectional effects between sleep and behavioral/emotional regulation exists. Although the past decade has seen research progress in these areas, there continue to be major gaps in existing knowledge and a paucity of well-controlled studies to guide specific health policy decisions and recommendations regarding sleep in adolescence. In particular, there is need for improved understanding of the acute and chronic effects of inadequate sleep in adolescents, guidelines for defining adequate sleep in adolescents, and a better delineation of the links among sleep, behavior, and affect regulation. Finally, this paper briefly examines one specific application of this knowledge area regarding early starting times among some high schools.