Association of state happiness with mortality: Evidence from a prospective cohort study in Japan.

OBJECTIVE: The aim of this study was to examine whether the association between happiness and all-cause mortality persists after adjustment for health status and sociodemographic factors in Japanese adults. The study addressed the gap in understanding the relationship between happiness and mortality in Japanese populations. METHOD: A total of 3,187 adults from Minami-Izu, Japan, were included in a prospective study tracking all-cause mortality from October 2016 to October 2023. Happiness was assessed using a single-item, self-report measure of state emotional well-being. Sociodemographic factors (age, sex, marital status, education, and economic status) and health status (body mass index and physical function) were considered as covariates. Binary logistic regression models were used to examine the association between happiness and mortality, adjusted for these factors. RESULTS: During the follow-up, 277 participants died. The risk of all-cause mortality was higher in those who reported being unhappy compared with those who reported being happy after adjustment for age and sex (OR: 2.69, 95% CI: 1.63-4.44) and also significantly higher in those who reported being unhappy compared with those who reported being happy after adjustment for age, sex, all socioeconomic factors and health status (OR: 1.85, 95% CI: 1.09-3.16). Sensitivity analyses excluding deaths within the first year showed consistent results. CONCLUSIONS: Happiness is independently associated with reduced mortality risk, even after adjustment for sociodemographic and health status factors. These findings highlight the importance of promoting positive well-being in Japanese populations. (PsycInfo Database Record (c) 2026 APA, all rights reserved).