[The characteristics of sleep-wake rhythm in adolescents aged 15-20 years. A survey made at school during ten consecutive days].

UNLABELLED: Adolescents' fatigue is a worrying subject.

PATIENTS AND METHOD: A survey was carried out over a period of ten days (a school week between two weekends). Through a daily questionnaire, 386 adolescents aged 15-20 years were asked about sleep onset and offset, time delay of sleep onset, quality of sleep, daytime sleepiness and naps.

RESULTS: The results confirmed that the length of sleep was lessened during weekdays. This duration was one hour shorter than on Saturday nights or during holidays. However, a significant delay occurs in sleep onset on Saturday nights and sleep offset on Sunday mornings, which represents the main irregularity in the sleep schedule. Poor quality of sleep is due to difficulties in sleep onset (16%) and night awakenings (39%). Daytime sleepiness is reported by 38% of the adolescents, and many of them have a nap on Sundays, or other days of the week. Daytime activities (out-of-school sports, particularly) and evening activities were studied as well as the use of hypnotics and stimulants.

CONCLUSION: This work stresses sleep insufficiency during the week at school, changes in sleeping patterns during weekends, and sometimes poor quality of sleep. Similar facts have already been found in children, and this may explain the consequences on the life and behaviour of adolescents. The population has to be informed about the effects of sleep on health.