Interaction effects of sex on the sleep loss and social jetlag-related negative mood in Japanese children and adolescents: a cross-sectional study

STUDY OBJECTIVES: Sleep problems, such as accumulated sleep loss and social jetlag (SJL), which is characterized by a discrepancy in a person’s sleep pattern between the weekday and the weekend, are associated with physical and mental health problems, and academic performance in young ages. However, sex differences in these associations are not fully understood. The purpose of this study was to investigate the effect of sex on sleep-related factors, mental health (negative mood), and academic performance in Japanese children and adolescents. METHODS: A cross-sectional online survey was conducted with 9270 students (boys: N = 4635, girls: N = 4635) ranging from the fourth grade of elementary school to the third grade of high school, which typically includes ages 9–18 years in Japan. Participants completed the Munich ChronoType Questionnaire, the Athens Insomnia Scale, self-reported academic performance, and negative mood-related questions. RESULTS: School grade-related changes in sleep behavior (e.g. delayed bedtime, shortened sleep duration, and increased SJL) were detected. Girls had greater sleep loss on weekdays and SJL on weekends than boys. Multiple regression analysis revealed that sleep loss and SJL were more associated with negative mood and higher insomnia scores in girls than in boys, but not with academic performance. CONCLUSIONS: Sleep loss and SJL in Japanese girls had a higher correlation to their negative mood and tendency to insomnia than in boys. These results suggest the importance of sex-dependent sleep maintenance for children and adolescents.