engleski

Circadian preference and sleep patterns of adolescents involved in two different systems of school time

Objectives: The first objective of our study was to explore differences in morningness-evenigness (ME) between adolescents attending school always in the morning and those who attend school one week in the morning and the other in the afternoon. The second objective was to examine the relationships between ME and characteristics of adolescents’ sleep. Methods: 183 high school students (modal age 16 years) completed the Initial Questionnaire as a part of a larger sleep study. Out of them 64 students (30 males) attended school each week in the morning, and 119 students (32 males) attended school one week in the morning and the other in the afternoon. The Questionnaire included questions on student’s sleep and a Morningness-Eveningness Scale for children (Carskadon et al, 1993). Data for sleep characteristics were analysed by means of univariate ANOVAs with school system (morning only, rotating shifts), and ME typology (Morning (M), Neutral (N) and Evening (E) types) as independent factors, and sleep characteristics as dependent measures. Results: The average ME scores did not differ between adolescents involved in different school systems. The main effect of ME was significant for the majority of sleep parameters, and no significant interaction between circadian type and school system was observed. Evening types reported the latest bedtime both on school days and weekends, and the latest wake-up time on weekends. Furthermore, compared to other circadian types, E types reported the shortest sleep on school days (E=403min ; N=428min ; M=439), and the longest sleep on weekends (E=568min ; N=544min ; M=520). The observed differences in wake up time and sleep duration between school days and weekends were the greatest for the E types. Evening types reported greater sleep need compared to morning types (E=570min ; M=520), and their sleep debt during school days (with respect to their sleep need) was greater than sleep debt of other types (E=167min ; N=109min ; M=81min). Conclusion: Adolescents involved in different school systems do not differ in their ME preferences. Eveningness preferences are consistently associated with shorter sleep and greater sleep debt on school days, and greater irregularity of sleep patterns, irrespective of differences in organisation of school time.

adolescents ; circadian preferences ; school time system

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