Two consistent findings in the literature on adolescent sleep patterns are that time spent sleeping on school nights decreases from childhood through adolescence, and that differences between weekend and school-night sleep schedules are large for many teenagers (Billiard, Alperovitch, Perot, & James, 1987; Strauch & Meier, 1988; Carskadon, 1990; Szymczak, Jasinska, Pawlak, & Swierzykowska, 1993). In general, school-night sleep is restricted because of early school start times, whereas on weekends, bedtimes and rise times are later and total sleep time is longer. In a recent large survey of over 3,000 high school students, Wolfson and Carskadon (1998) found such irregular bedtimes related to self-reported academic difficulty in school, daytime sleepiness, depressed mood, and sleep-wake behavior problems. Lower amounts of self-reported total sleep time were also related to more difficulties with daytime functioning. We suspect that these difficulties in daytime function may result in part from disturbances in both the homeostatic and circadian timing systems regulating sleep-wake behavior.

Evidence from other studies in children and adolescents supports the importance of total sleep time and sleep schedule regularity as predictors of daytime functioning. Several other survey studies have linked total sleep time with grades, daytime fatigue and struggles to stay awake, and difficulties concentrating in class (Allen, 1992; Epstein, Chillag, & Lavie, 1995).