Gender differences in the association between long working hours and the onset of depressive symptoms in middle-aged and older workers in Korea: A population-based longitudinal study (2006–2022)

Background: Korean society is projected to undergo a rapid aging of its workforce. We explored gender differences in the association between working hours and the onset of depressive symptoms among middle-aged and older workers. Study design: This study included workers aged ≥45 years from a nationwide panel study with biennial follow-ups (n = 4941, observations = 18,531). Weekly working hours were self-reported. We employed generalized estimating equations with log link function to explore the association between working hours and the onset of depressive symptoms at the two-year follow-up. Main outcome measures: The 10-item version of the Center for Epidemiologic Studies Depression Scale. Results: The incidence of onset of depressive symptoms was 10.7 % among those working 35–40 h/week and 13.0 % among those working ≥55 h/week. In the overall sample, those working ≥55 h/week had increased risk of the onset of depressive symptoms at the two-year follow-up (risk ratio: 1.12, 95 % confidence interval: 1.01–1.24). There was a positive interaction between being female and working ≥55 h/week in their effect on the risk of onset depressive symptom (P = 0.010). In the gender-stratified analysis, working ≥55 h/week was associated with an increased risk of the onset of depressive symptoms at the two-year follow-up among women (risk ratio: 1.29, 95 % confidence interval: 1.08–1.53); however, we observed no clear associations among men. Conclusion: Long working hours are positively associated with the of onset depressive symptoms in middle-aged and older workers, and this association is pronounced among women.