engleski

Paying-off the sleep debt in adolescents attending school in shifts: are there similarities with shiftworkers?

Objectives: Studies show that early morning starts to the school day restrict the sleep of adolescents during a school week, and that sleep is extended the following weekend. The organisation of school time in Croatia does not limit opportunities for extended sleep to the weekend. The majority of Croatian adolescents attend school one week in the morning and the following week in the afternoon ; extended sleep is possible during the week of the afternoon shift. The question is whether additional opportunities for extended sleep affect sleep in the week with a morning schedule. This study compared the sleep of a group of adolescents attending continuously on the morning schedule, with a group attending for one week on the morning schedule followed by a week on the afternoon schedule. Methods: Two groups of secondary school students aged 16 years participated. One group (N1=76, 27 girls) attended school between 8.00 and 13.00. The other (N2=97, 55 girls) attended between 8.00 and 13.00 in one week, and between 14.00 and 19.00 in the following week. The school week consisted of 5 days with free weekends. Sleep data were collected using sleep-wake diaries. The characteristics of the main sleep in the two groups were compared by ANOVA. Differences between the groups in daytime sleepiness and napping were tested by Chi-square tests. Individual differences in sleep extension at the weekend were examined by correlation analyses. The relationship between napping and sleep duration was examined by ANOVA. Results: The duration of the main sleep on school nights of a morning schedule (M1 =6.74, SD1=0.97 ; M2 =6.82, SD2=0.67) was significantly shorter than on weekend nights (M1 =8.81, SD1=1.60 ; M2 =9.01, SD2=1.34), but did not differ between the two groups. Adolescents from the two systems did not differ in daytime sleepiness or in naps taken on school and weekend days. In both groups, a shorter main sleep on school nights was associated with more frequent napping during the school week and longer sleep extension at the weekend. Conclusion: Adolescents who attend school in two weekly rotating shifts do not change their main sleep or napping during a week on the morning schedule, because opportunities for additional sleep are anticipated in the following week while on the afternoon schedule. Both extension of sleep at the weekend and napping on school days are used to compensate for reduced main sleep, indicating some similarities with shift workers paying-off the sleep debt.

School start time; Sleep restriction; Sleep extension; Double-shift schools

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