Sleep behavior of South African adolescents.

STUDY OBJECTIVES: To survey a large group of South African adolescents about their sleep behavior, daytime behaviors, and morning alertness as compared to those of other teenagers worldwide.

DESIGN: Subjects completed a questionnaire about their sleep habits and daytime behaviors on the previous day, and subjective morning alertness at the time of completing the questionnaire.

SETTING: Four secondary schools in Johannesburg, South Africa on mid-week mornings.

PARTICIPANTS: 825 secondary school students volunteered for this study.

INTERVENTIONS: N/A.

MEASUREMENTS AND RESULTS: The students, (16+/-1 years), 61% female, reported significantly less time in bed (p<0.001) on a school night (453+/-70 minutes), compared to weekend nights (476+/-128 minutes). On the school night, they reported a mean sleep onset latency of 17 minutes, with 45% of the sample falling asleep in less than ten minutes. Short sleep onset latency and short in-bed wakefulness both were positively related to a high sleep efficiency and subjective sleep quality. On the previous day, 72% of the adolescents had consumed caffeinated beverages and 56% had exercised, but these behaviors did not significantly influence their nighttime sleep. The majority (77%) of students had napped the previous day and 8% had taken medication to fall asleep that night. 40% of the students felt that they could fall asleep mid-morning, if given the chance, but their sleepiness was independent of their nighttime sleep quality or duration.

CONCLUSIONS: Similarly to teenagers around the world, South African adolescents get insufficient sleep during the week, which they attempt to compensate for on the weekends. A large proportion of the students are also sleepy during the school day, which may influence their academic performance.