Maturational trend of daytime sleep propensity in adolescents

Study Objectives: The teenage increase in sleepiness is not simply a response to decreasing nighttime sleep duration. Daytime sleepiness increases across adolescence even when prior sleep duration is held constant. Here we determine the maturational trend in daytime sleep propensity assessed with the multiple sleep latency test (MSLT) and assess the trend’s relation to pubertal maturation and changes in the sleep electroencephalogram. We also evaluate whether the relation of daytime sleep propensity to prior sleep duration changes between ages 10 and 23 years. Methods: Participants (n = 159) entered the study between ages 9.8 and 22.8 years and were studied annually for up to 3 years. Annually, participants kept each of three sleep schedules in their homes: 7, 8.5, and 10 hours in bed for 4 consecutive nights with polysomnography on nights 2 and 4. MSLT-measured daytime sleep propensity was assessed in the laboratory on the day following the fourth night. Results: A two-part linear spline model described the maturation of daytime sleep propensity. MSLT sleep likelihood increased steeply until age 14.3 years, after which it did not change significantly. The maturational trend was strongly associated with the adolescent decline in slow-wave (delta, 1–4 Hz) EEG power during NREM sleep and with pubertal maturation assessed with Tanner stage measurement of breast/genital development. The effect of prior sleep duration on sleep likelihood decreased with age. Conclusions: Adolescent brain changes related to pubertal maturation and those reflected in the delta decline contribute to the adolescent increase in daytime sleep propensity.