engleski

Associations of the timing of physical activity during the day with duration and quality of sleep in adolescents

Purpose: The aim of this observational study is to determine the way in which the period of performing physical activity affects sleep quality and duration based on objective measurement. Methods: This investigation is a part of the CRO- PALS study. For the purpose of this investigation, 123 adolescents (mean age=15.6 years, SD=0.4) with objective data on both sleep and physical activity (PA) were included in the analyses. To objectively measure sleep and PA we asked the participants to wear the SenseWear Pro3 Armband™ (SWA) activity and sleep monitor (BodyMedia Inc) for 5 consecutive days. PA was divided according to intensity in 2 categories ; 4 to 7 METs was categorized as moderate physical activity, while physical activity of intensity greater than 7 METs was categorized as vigorous physical activity. Four periods in the day were examined (6-12 a.m., 12-6 p.m., 6-9 p.m. and 9-12 p.m.). The sleep parameters examined were: total sleep time as an indicator of sleep quantity, and sleep efficiency and sleep onset latency as indicators of sleep quality. The hypothesis that there is an association between the period of physical activity with sleep was tested by multilevel modeling for repeated measures with different activity parameters or a part of the day as independent variables and individual sleep parameters as dependent variables. All models included interaction between sex and physical activity in a period of the day. Significant interactions were observed only for physical activity in the period 21-24h and sex for sleep onset latency and these analyzes were repeated within a male and female sex separately. Results: Physical activity was not associated with total sleep time or sleep efficiency in neither of the periods of the day examined (p=0, 09-0, 88). Conversely, physical activity performed after 9 p.m. was accompanied with longer sleep onset latency in girls (p<0, 001), but not in boys (p=0, 81). This particularly refers to vigorous physical activity, with every 30 minutes of PA followed by 35 minutes longer sleep onset latency. Conclusion: Girls should avoid vigorous physical activity after 9 p.m. in order not to prolong sleep onset latency

exercise ; sleep ; school age children ; pediatric population

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