Subjective and objective measures of sleep patterns and sleepiness as predictors of depressiveness in adolescents on rotating school schedules

Introduction: Our previous survey and diary studies have shown that the adolescents attending school on rotating morning and afternoon school schedules obtain recommended amount of sleep and schedule their sleep at preferred time in 9 out of 14 days of such schedule. In this study, we wanted to compare several objective and subjective indices of sleep and sleepiness over two consecutive weeks with different school start times (SST). We also wanted to examine the relative contribution of different sleep and sleepiness measures in predicting depressiveness on weekends following each school schedule. Methods: A total of 21 secondary school students (11 females, 16 y) participated in the study. They were keeping sleep-wake diaries, wearing wrist actigraphs, and giving sleepiness ratings at predesignated times with actigraph-score option for two consecutive weeks with alternating morning and afternoon SST, and the respective week-ends. On Fridays of each school week they came to laboratory where MSLT measurements were conducted four times at two-h intervals. Results: During both school weeks students went to bed at similar times, reported similar sleep quality and had similar sleep efficiency. However, on week with afternoon SST they slept on average 81 min longer (p< 0.001) due to significantly later wake-up times. On week with morning SST, social jetlag was on average 2.03 h in contrast to 1.23 h on week with afternoon SST (p< 0.01). Differences in self-reported sleepiness during school weeks and in physiological sleepiness at the end of school weeks with different SST were not found. Regression model for morning schedule explained 53.2% of variance of depressive symptoms (p< 0.05), with average sleep duration and subjective daytime sleepiness being significant individual predictors. Physiological sleepiness at the end of school week did not predict depressiveness on the respective weekend. The regression model for afternoon school schedule was overall not significant. Conclusion: In adolescents on weekly rotating school schedules, morning SST results both in shorter sleep duration and greater sleep irregularity between school days and weekends than the afternoon SST. Our results indicate that sleep loss on school days and subjectively reported sleepiness have a significant impact on depressive symptoms reported on weekend following morning SST. Disclosure: No