Adolescence is accompanied by striking changes in sleep behavior and in the phenomenology of sleep. Maturational changes in the central nervous system underlie changes in adolescent sleep structure. Sleep behaviors change during adolescence in response to maturational changes in sleep regulatory processes and competing behaviors. This pattern leads to insufficient sleep for many teens on school nights. Associations of reduced sleep with poorer school performance beg the question of how prelearning and posttraining sleep affect the learning process. Thus, insufficient sleep can impair acquisition and retrieval when sleep reduction results in sleepiness, irritability, distractibility, inattention, and lack of motivation. Strong evidence indicates that adequate sleep enhances memory consolidation and resistance to interference. Hence, insufficient sleep can also threaten learning by jeopardizing this part of the memory formation process.