RESUMEN
BACKGROUND: Sleep shortage has been pervasive among pupils. METHODS: Multiple regression analysis was used to analyze 2,722 questionnaires obtained from grade 5 to 12 pupils, to determine factors associated with sleep duration. RESULTS: Significant regression formulae for sleep duration were obtained for all school types: adjusted R2 / P value were 0.14/<0.001 for elementary school; 0.11/<0.001 for junior high school; 0.06/<0.001 for high school. Longer after-school activities (standardized regression coefficient/ P value were -0.22/<0.001 for elementary school; -0.10/<0.01 for junior high school; -0.18/<0.001 for high school) and more sleepiness (-0.09/<0.001 for elementary school; -0.07/<0.05 for junior high school; -0.07/<0.05 for high school) were significantly associated with reduced sleep duration for all school types. In both elementary and junior high schools, the higher grade (-0.53/<0.001 for elementary school; -0.10/<0.01 for junior high school), and longer weekday screen time (-0.15/<0.001 for elementary school; -0.19/<0.001 for junior high school) were also significantly associated with sleep loss. In elementary school, irregular dinner (-0.07/<0.05), breakfast skipping (-0.11/<0.001), longer weekend screen time (-0.09/<0.05) and better self-reported academic performance (0.07/<0.05) also revealed significant associations with sleep loss. In high school, reduction of sleep duration was also significantly associated with higher standardized body mass index (-0.08/<0.05). CONCLUSIONS: Excessive after-school activity might be considered in association with pupils' sleep reduction.