engleski

Sleep patterns of adolescents attending classes in two shifts

In comparison to the children, the adolescent sleep patterns remarkably change due to combined influences of biological and psychosocial factors. As they get older, the adolescents tend to go to sleep later in the evenings, sleep longer in the mornings and the difference between their weekday and weekend sleep patterns increases (1). Since on weekdays their wake time is still being determined by the early school start time, many adolescents worldwide tend to sleep less than minimally recommended 8.5 hours. The majority of students in Croatia, both in elementary and high schools, attend classes in two shifts. They usually go to school one week from 08:00 to 13:00 and the next from 14:00 to 19:00. In this study we wanted to examine the effects of two-shift schedule of school time on the sleep characteristics of the adolescents. During October and November 2001 and 2002 students from 5th to 8th grades of elementary school and from 1st to 4th grades of high school were examined in Zagreb. A total of 2365 students from 24 schools completed the Croatian version of School Sleep Habits Survey (2). In this study the results of 1921 students of both genders were analyzed. Their median age ranged from 11 years in the 5th grade of elementary school to 18 years in the 4th grade of high school. ANOVA showed the effect of grade to be statistically significant for all sleep variables. As adolescents progress from the 5th grade of elementary school to the 4th grade of secondary school they go to bed later on morning shift week (F7/1806=77.2), afternoon shift week (F7/1806=48.6) and on weekends (F7/1806=121). Although the school start time in Croatia does not change with transition to high school, older adolescents tend to wake up somewhat earlier on the morning shift week (F7/1806=52.9), since they travel longer to school. On the other hand, older adolescents wake up later than younger ones on the afternoon shift week (F7/1806=2.2) and on weekends (F7/1806=31.2). The sleep length curtails in older adolescents on the morning shift week (F7/1806=126), afternoon shift week (F7/1806= 33.4) as well as on weekends (F7/1806=37.7). Transition to higher grades also results in more pronounced differences in sleep length and bedtime between morning- and afternoon shift weeks on the one hand, and weekends, on the other. Regarding sleep characteristics the adolescents from Zagreb experience beneficial effects of two-shift school schedules. During the afternoon shift and on weekends they generally manage to get enough sleep. They are partially sleep deprived only during five days of the morning shift. Future laboratory and field studies will explore the effects of two-shift school schedules on adolescents’ daytime functioning and sleepiness. 1. Carskadon MA Adolescent Sleep Patterns – Biological, Social, and Psychological Influences. Cambridge: Cambridge University Press, 2002. 2. Wolfson AR, Carskadon MA. Sleep schedules and daytime functioning in adolescents. Child Development 1998 ; 69:875-87.

sleep; adolescents; shiftwork

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