Among the many behavioral changes associated with adolescent development are later bedtimes and less sleep. This article presents an overview of healthy adolescent sleep in humans along with a review of the maturation of homeostatic (process S) and circadian (process C) processes regulating sleep. We propose that maturational changes to the homeostatic and circadian processes push adolescents toward later bedtimes, while societal demands, such as early school start times, result in a pattern of insufficient and ill-timed sleep. The implications of sleep curtailment during this developmental period are discussed.