The Relationship Between Psychological Distress, Precarious Employment, and Unpaid Work Hours in Japanese Adults: Generalized Linear Mixed Model Using Longitudinal Survey of Adults in the 21st Century.

backgroundPrevious studies indicate that precarious employment harms mental health, but the association when combined with unpaid work remains unexplored. This study examined the relationships between psychological distress, employment status, and unpaid work in Japan, where women often engage in precarious work and bear the majority of unpaid work.

methodsWe analyzed data from the Longitudinal Survey of Adults in the 21st Century. Poisson regression analysis with robust standard errors was conducted using a mixed-effects model stratified by gender to calculate adjusted risk ratios (aRR). Additionally, sensitivity analyses were performed by altering the outcome's cutoff point.

resultsThe risk of psychological distress decreased with regular permanent employment for women (aRR = 0.90, 95% CI = [0.85, 0.96]), while no significant association was observed for men (aRR = 0.93, 95% CI = [0.86, 1.01]). Unpaid work hours showed no main effects. For women, an additive negative interaction was observed between employment status and unpaid work hours (relative excess risk due to interaction [RERI] = -0.12, 95% CI: [-0.22, -0.02] for precarious work × 3rd quartile of unpaid work hours; RERI = -0.15, 95% CI: [-0.28, -0.02] for precarious work × 4th quartile unpaid work).

conclusionsThe findings suggest that the mental health benefits of regular employment for women are attenuated by longer unpaid work hours, highlighting the "dual burden" of paid work and disproportionate domestic responsibilities. Consequently, policies aimed solely at increasing job security are insufficient. To improve public mental health, interventions must simultaneously address the gender disparity in unpaid work by promoting work-life balance and redistributing domestic loads.