engleski

View from Croatia: The interplay between chronotype and irregular school start times

In Croatia more than 50% of primary and secondary school still switch school start times for students weekly. It means that the same students attend school one week in the morning and the other in the afternoon. At the Institute for Medical Research and Occupational Health in Zagreb we have conducted a series of studies examining the effects of such school start time rotation to sleep patterns and daytime functioning of adolescents. The main findings from two studies – the survey study (N = 2363, 11-18 yrs, 52% f) and the diary study (N = 97, 15-17 yrs, 57% f) are central to this presentation. Differences in bedtime, wake-up time, and sleep duration between three situations (school days with morning schedule, school days with afternoon schedule, and weekends) across age and across chronotype will be presented. The delay in sleep timing and expected differences in sleep duration depending on the situation, age and chronotype will be shown. It will be demonstrated how all age groups and each chronotype manage to get the minimally recommended 8.5h of sleep on 9 out of 14 consecutive nights (school nights and weekend nights). Furthermore, the importance of the first weekend night after the morning schedule for paying off the sleep debt accumulated over that school week will be shown. It will also be pointed how daytime functioning of such “shift-working adolescents” is generally well preserved. On school days with morning schedule somewhat more pronounced sleepiness upon waking and slightly higher depressive symptoms were observed, but overall it seems that different sleep opportunities do not result in significantly different levels of daytime impairment. Individual differences in morningness-eveningness preferences remain the most consistent predictor of self-reported measures of daytime functioning.

adolescents, sleep, daytime functioning, alternating shifts

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