ABSTRACT
Backgrounds: Sleepiness is reported to predict sleep quality, academic performance and self-regulation. This study aimed to discover determinants of sleepiness. Methods: On 2722 questionnaires obtained from pupils in grades 5 - 12 in the Kanto district of Japan, lifestyle habits associated with sleepiness were analyzed using a multivariable logistic regression model. Results: The rate of sleepy pupils (who feel sleepy during class as often and always) increased from elementary school (6.3%) to senior high school (42.4%) via junior high school (17.1%). Higher grade (adjusted odds ratio [OR], 1.28; 95% confidence interval [CI], 1.21 - 1.37; p < 0.001), later bedtime before school day (OR, 1.41; CI, 1.26 - 1.57; p < 0.001), longer non-school day screen time (OR, 1.27; CI, 1.16 - 1.40; p < 0.001), poor self-reported academic performance (OR, 1.41; CI, 1.24 - 1.60; p < 0.001), skipping breakfast (OR, 1.18; CI, 1.01 - 1.39; p = 0.041), earlier wake time on school day (OR, 0.84; CI, 0.71 - 0.98; p = 0.026), and higher after-school (OR, 1.03; CI, 1.02 - 1.04; p < 0.001) and physical activities (OR, 1.06; CL, 1.03 - 1.10; p < 0.001) were independently associated with sleepy pupils. Conclusions: To reduce adolescents’ sleepiness in the Kanto district of Japan, we recommend them to have adequate waking time, and to avoid late bedtime, breakfast skipping, excessive screen time, after-school activity, and physical activity. Further prospective studies are needed to confirm involvements of these recommended factors in sleepiness and both physical and mental health outcomes.