Previous research has suggested that extensive television viewing may be associated with a variety of sleep problems during childhood and adolescence. This study of 759 families from 2 upstate New York counties followed subjects at ages 6, 14, 16, and 22 years. Adolescents who watched 3 or more hours of television per day were at significantly increased risk for frequent sleep problems at age 22 years, even after adjusting for a variety of personal and family characteristics. Adolescents who reduced their television watching to less than 1 hour per day had a reduction in subsequent sleep problems. This study indicates another important negative effect of excessive television watching among children and adolescents.