Non-School Day Catch-Up Sleep among Pupils in Japan

Abstract

Backgrounds: Weekend catch-up sleep is the difference in sleep duration between the weekend and weekdays, and reflects sleep debt, whose significance is hypothesized to be altered by weekday sleep duration. This study aimed to assess this hypothesis. Methods: Multiple-comparison tests and multiple-regression analyses were conducted on questionnaires asking various lifestyle habits obtained from 2722 pupils in grades 5 to 12 and stratified by groups of pupils with shorter (≤7 hours) or longer (>7 hours) sleep duration on the nights before schooldays. Results: The percentage of pupils in negative non-school day catch-up sleep category was 6.6%, whereas that in non-school day catch-up sleep > 2 hours was 14.4%. In comparison with the reference category (non-school day catch-up sleep of zero), multiple comparison tests on lifestyle habits revealed significantly longer screen time in the shorter sleep-duration group of pupils with negative non-school day catch-up sleep and those with non-school day catch-up sleep > 2 hours. This analysis also demonstrated a significantly longer screen time in the longer sleep-duration group of pupils with non-school day catch-up sleep > 2 hours. Physical activity in pupils with negative non-school day catch-up sleep in the longer sleep-duration group was significantly longer, while that in pupils with non-school day catch-up sleep > 2 hours in the shorter sleep-duration group was significantly shorter. In the longer sleep-duration group, pupils with non-school day catch-up sleep > 2 hours showed poorer academic performance. Multiple regression analysis revealed that longer physical and after-school activities were significantly associated with non-school day catch-up sleep decrease in both the study groups. In the longer sleep-duration group, male gender, shorter screen time, and higher standardized body mass index were significantly associated with decreased non-school day catch-up sleep. Conclusions: Sleep duration before school days contributed differently to the non-school day catch-up sleep evaluation.