A key task for schools is to ensure that the conditions in which learning is to take place address the biological needs of the learners. This book examines sleep needs of adolescents and discusses the implications of these needs for school starting times. This book is a collection of five articles that appeared in a special section of the Phi Delta Kappan in January 1999. The chapters are: (1) "The Prickly Politics of School Starting Times" (Kyla L. Wahlstrom); (2) "When Worlds Collide: Adolescent Need for Sleep versus Societal Demands" (Mary A. Carskadon); (3) "The Consequences of Insufficient Sleep for Adolescents: Links between Sleep and Emotional Regulation" (Ronald E. Dahl); (4) "The Impact of School Starting Time on Family Life" (Gordon D. Wrobel); and (5) "Starting Time and School Life: Reflections from Educators and Students" (Patricia K. Kubow, Kyla L. Wahlstrom, and Amy E. Bemis). (KB)