The relationship between subjective happiness and sleep problems in Japanese adolescents

Objectives: Low sleep quality in adolescents is an important public health concern, as it relates to both their current and future physical and mental health. Furthermore, subjective happiness is also often regarded as a major life goal. Although Japan is an economically powerful country, the reported levels of subjective happiness among Japanese adolescents is low. Thus, this study aims to examine the relationship between subjective happiness and sleep problems in Japanese adolescents. Methods: We conducted a nationally representative cross-sectional study of adolescents enrolled in junior and senior high schools in Japan. We used a questionnaire to determine the prevalence of sleep problems (eg, insomnia, short sleep duration (SSD) and poor sleep quality) and to evaluate the participants' reported levels of subjective happiness. Multivariable logistic regression analyses were used to examine the associations between subjective happiness and sleep problems. Adjusted variables were basic demographic characteristics (eg, gender and school grade), lifestyle behaviors, and mental health status. Results: Data from 64,329 students were analyzed (age range 12–18 years, mean age 15.7 years, 53.9% male). The results indicated that reported levels of subjective happiness were strongly associated with the prevalence of sleep problems. Linear relationships can be observed between sleep problems and subjective happiness scores. The multivariable logistic regression analysis showed that dose–response association of subjective happiness score was observed with all three sleep problems. Conclusions: Due to these findings, we recommend that policy makers and school officials educate adolescents on the importance of both subjective happiness and good sleep hygiene.