engleski

Phase preferences and sleep patterns of adolescents attending school in two shifts

One of the factors that determine adolescent sleep patterns is the phase shift in their preferences towards more pronounced eveningness. Since their wake time is determined by early school start time, many adolescents worldwide do not get enough sleep. We examined the relationship between morningness-eveningness and sleep patterns of adolescents attending school in two shifts, one week in the morning and the other in the afternoon. The data of 2287 students from 12 elementary and 12 high schools in Zagreb were analysed. The students completed the Croatian version of School Sleep Habits Survey (Wolfson & Carskadon, Child Dev 1998 ; 69:875-87), which comprised the Morningness-Eveningness scale for children. The participants' age ranged from 11 to 18 years. The number of male and female participants did not statistically differ between age groups. Univariate ANOVA showed that, irrespective of age, females had somewhat more pronounced morning preferences than males (F(1/2115)=5.52, p<0.05). With increasing age both female and male adolescents reported more pronounced evening preferences (F(7/2115)=2.7, p<0.01). In order to compare actual bedtimes, wake-up times and sleep duration of morning "types" (M), neither "types" (N), and evening "types" (E) the sample was divided into categories according to the morningness-eveningness score. The comparisons were made separately for morning shift week, afternoon shift week and weekends. The results of multivariate ANOVAs showed that E-"types" reported the latest bedtimes and wake-up times on both morning and afternoon shift week, and on weekends. On morning shift week the sleep duration of E-"types" was the shortest (ME-"types" =440min, S.E.=3min ; MN-"types" =463min, S.E.=2min ; MM-"types"=482min, S.E.=3min ; F(2/2083)= 58.62, p<0.01) and on weekends the longest of all groups (ME-"types"=580min, S.E.=5min ; MN-"types"=570, S.E.=3min ; MM-"types"=549min, S.E.=4min ; F(2/2031)=14.84, p<0.01). There was no significant main effect of phase preference on sleep duration on afternoon shift week. Regarding sleep regularity E-"types" had the most pronounced bedtime delay and sleep extension on both afternoon shift (delay F(2/2069)=9.54, p<0.01 ; extension F(2/2069)=37.2, p<0.01) and on weekend (delay F(2/2013)=13.88, p<0.01 ; extension F(2/2013)=77.08, p<0.01) when compared to morning shift week, as well as on weekend when compared to afternoon shift week (delay F(2/2055)=4.87, p<0.01 ; extension F(2/2013)=16.06, p<0.01). The interactions of phase preferences, age and/or gender on sleep patterns were not statistically significant. Evening Preferences in Adolescence Contribute to Greater Sleep Irregulatory ans Short Sleep on Morning Shift Week.

morningness-eveningness; sleep duration; sleep regularity

DOI: 10.1111/j.1365-2869.2008.00690.x