How work and family dynamics shape mental health across the life course: Insights from a longitudinal study in Japan

•Family status changes modified the within-person impact of the psychosocial work environment on women's mental health.•Entering into marriage strengthened the positive association between flexible work arrangements and women's mental health.•Acquiring a parental role weakened the positive association between flexible work arrangements and women's mental health.•The mental health impact of the psychosocial work environment remained stable for men, regardless of family status changes.