Prolonged Overtime Predicts Worsening Burnout among Healthcare Workers: A 4-Year Longitudinal Study in Taiwan

Background: Overtime adversely affects physical and mental health, contributing to irritability, anxiety, reduced sleep, and even cardiovascular issues, ultimately lowering care quality and increasing turnover intentions. Whether overtime directly correlates with burnout can be explored with longitudinal studies that test this link. Methods: This longitudinal study analyzed secondary data from four survey waves (2021–2024) involving healthcare workers at a medical university hospital in Taichung, Taiwan. Burnout was assessed using the personal burnout (PB) scale from the Copenhagen burnout inventory (CBI), with high PB levels (HPBL) defined as scores in the upper quartile of the 2021 baseline. Survival analysis utilizing the Kaplan–Meier method and Cox regression investigated burnout progression and the effects of overtime. Results: HPBL was defined as PB scores ≥45.83 (upper quartile in 2021). The proportions of HPBL were 30.28% (2021), 33.29% (2022), 36.75% (2023), and 32.51% (2024). Survival analysis confirmed that the risk of burnout increased over time, with the survival time estimated at 2.50 ± 0.03 years and lower survival probabilities observed among participants working overtime (Log-rank test, P < 0.0001). Cox regression revealed overtime work, female gender, being a physician/nurse, reduced sleep, and overweight/obesity as independent risk factors for HPBL (HR = 2.13 for overtime, P < 0.001). These findings support the hypotheses on burnout progression and the impact of overtime. Conclusion: Overtime significantly heightens the risk of burnout, which worsens over time. Female sex, healthcare roles, obesity, and insufficient sleep are additional risk factors. Limiting overtime and proactive interventions are crucial to preventing burnout in healthcare workers.