engleski

Interindividual differences in napping and sleep extension in Croatian adolescents attending school in two shifts

If school time is arranged one week in the morning, the other in the afternoon, and weekends are off, then early start of school restricts sleep only on days of morning shift, while opportunities for longer sleep exist both on weekends and days of afternoon shift. Therefore, Croatian adolescents involved in such a school system report reduced sleep on days of morning shift, and extended sleep on weekend and afternoon shift days. In present study we examined individual differences in paying off the sleep debt from morning shift days by napping or by extension of main sleep in situations with opportunities for longer sleep. Adolescents 11-18 years of age (n=2363, 52% females) were surveyed by means of the Croatian version of School Sleep Habits Survey. In all age groups the main sleep duration on morning shift days was positively associated with main sleep duration on weekends and afternoon shift days ; adolescents reporting shorter sleep on morning shift days reported also shorter sleep in situations with opportunities for longer sleep. At the same time, in all age groups sleep duration on morning shift days was negatively associated with the amount of sleep extension both on weekend days and afternoon shift days ; adolescents with shorter sleep on morning shift days extended their sleep on weekends and afternoon shift days more than those with longer sleep. A significant increase of number of adolescents napping was observed from the 11-year age group (36%) to the 18-year age group (71%). Adolescents who napped reported greater sleep need than adolescents who did not nap in all age groups. However, adolescents who napped reported shorter sleep on days of morning shift than adolescents who did not nap only in 16- and 17-year olds. These results indicate that adolescents attending school in two shifts use extension of main sleep in situations with less external constraints to pay off insufficient sleep from morning shift days. Napping is a strategy used for paying off the sleep debt only in some adolescents.

naps; sleep deprivation; sleep extension; school schedule; interindividual differences

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