Associations of combined work schedules and atypical working hours with mental health among South Korean police officers: a cross-sectional study

Abstract

Background: Atypical working hours, including long working hours and weekend work, are established psychosocial risk factors for poor mental health and suicide in the general working population. Despite South Korea’s demanding working environment—characterized by extended hours—the mental health effects of combined atypical working hours and work schedules remain poorly understood, particularly in high-risk occupations such as policing. This study compared mental health outcomes among police officers according to combinations of work schedules and atypical working hours. Methods: This cross-sectional study analyzed data from 1,087 police officers collected in 2022 as part of the Mental Health Cohort of Police Officers in Korea. Combined work patterns were defined by work schedules (rotating shift work vs. fixed-day work) and atypical working hours: long working hours (> 52 h/week) and weekend work (≥ 4 h on weekends). Associations with mental health outcomes were examined using Poisson regression to estimate prevalence ratios and 95% confidence intervals (CIs). Analyses were stratified by sex for work schedule comparisons and pooled with sex adjustment for combined patterns to ensure statistical power. Results: Rotating shift work was associated with a higher prevalence of insomnia than fixed-day work, with more than a twofold increase among female officers (multivariable-adjusted prevalence ratio [aPR] = 2.38, 95% CI = 1.11–5.11). In pooled analyses, rotating shift work with or without long working hours was associated with insomnia compared with fixed-day work without long working hours or weekend work. Notably, fixed-day work combined with both long working hours and weekend work exhibited the highest aPRs for insomnia (aPR = 2.76, 95% CI = 1.23–6.16) and anxiety (aPR = 2.50, 95% CI = 1.27–4.89), and was significantly associated with depression (aPR = 1.61, 95% CI = 1.04–2.52). Conclusions: Rotating shift work was associated with insomnia, whereas the combination of long working hours and weekend work within fixed-day work showed the strongest associations with insomnia, depression, and anxiety. These results suggest that circadian variability primarily affects sleep among shift workers, whereas psychosocial variability (e.g., mandatory or unpredictable overtime) may contribute to insomnia, depression, and anxiety concurrently among fixed-day workers. Organizational interventions to limit mandatory overtime and reduce schedule unpredictability are urgently needed to protect police officers’ mental health.