The objective of this Child and Adolescent Mental Health Academic Award application is to assist in scholarly activities in the chronobiology of Childhood and Adolescent Mood, Sleep and Seasonality and to develop a Biomedical Research Section within the Division of Child and Adolescent Psychiatry. This award will focus his efforts in five specific areas: review and refine criteria needed to diagnose bipolar mood disorders in children and adolescents and develop operational definitions of mania, hypomania and hyperthymia; investigate the epidemiology of Seasonal Affective Disorder (SAD) in junior and senior high school students; develop ambulatory measures of circadian and infradian (seasonal) behavioral rhythms of mood, energy, sleep and appetite to validate the symptoms reported in highly seasonal adolescent; initiate a series of treatment studies to determine the most effective timing and duration of phototherapy for adolescents with SAD; and develop family cohorts for the study of the genetic aspects of mood, sleep and seasonality. These research projects would occur within the context of a Family Mood, Sleep and Seasonality Clinic.