Working hours and the onset of suicidal ideation and depressive symptoms: A 10-year nationwide longitudinal study in South Korea (2012-2022)

Long working hours are associated with adverse health outcomes. We investigated the association between working hours and suicidal ideation and depressive symptoms. We analyzed a nationally representative sample of 11,116 Korean workers, comprising 64,661 observations from 2012 to 2022, to investigate how working hours were associated with mental health problems. To account for repeated measurements in each participant, we employed a generalized estimating equation to estimate risk ratios (RRs) and 95% confidence intervals (CIs). Of the total observations, 13.1% reported working ≥55 h/week. The RR (95% CI) of the association between long working hours and onset of suicidal ideation in the subsequent year was 1.20 (0.95-1.53) for 41-48 h, 1.35 (1.02-1.78) for 49-54 h, and 1.56 (1.23-1.98) for ≥55 h/week, compared to 35-40 h/week. The RR (95% CI) of the association between long working hours and onset of depressive symptoms in the subsequent year was 1.19 (1.07-1.34) for 41-48 h, 1.11 (0.97-1.28) for 49-54 h, and 1.24 (1.10-1.40) for ≥55 h per week, compared to 35-40 h/week. Those working fewer than 35 h/week also had an increased risk of suicidal ideation and depressive symptoms. Policy interventions are needed to reduce excess working hours and protect workers' mental health.