8288018 Night and shift work and medically certified sickness absence due to common mental disorders among healthcare staff: a prospective cohort study

<h3>Objective</h3> The aim is to investigate the risk of first-time medically certified sickness absence (&gt;14 days) due to common mental disorders (CMDs) in healthcare staff by types of shift work (shift work with evenings and/or night shifts, consecutive nights and quick returns). <h3>Methods</h3> The design was a prospective cohort study with an 11-year follow-up. 25,631 nurses and nurse assistants with more than 100 shifts per year employed for at least one year between 2008-2019 by Region Stockholm were included. Detailed information on working hours was obtained from a computerized employee register. Data on first-time medically certified sickness absence due to CMDs (N=5,122) was obtained from the Swedish Social Insurance Agency. Cox regression analyses were used to estimate hazard ratios (HR), adjusting for age, profession, sex, and country of birth. <h3>Results</h3> A decreased risk of sickness absence due to CMDs was found among those who, during the preceding year, had night shift work (HR 0.80, 95% CI 0.72-0.89), and worked only nights (HR 0.81, 95% CI 0.65-0.99), compared to day workers. Frequently working nights (&gt;121 shifts in 1 year) showed a decreased risk of sickness absence (HR 0.77, 95% CI 0.65-0.90) compared to those who never work nights. Frequently (&gt;49 times in 1 year) having quick returns from afternoon shifts (&lt;11 h) showed a decreased risk of sickness absence (HR 0.87, 95% CI 0.75-1.00) compared to day workers. <h3>Conclusion</h3> Intensive night work was associated with a decreased risk of sickness absence due to CMDs in healthcare staff. The reason for this finding is not known but could be related to a selection of psychically fit individuals for night-work, partly related to mandatory medical examinations of night workers. <h3>Funding</h3> The study was funded by FORTE: Swedish Research Council for Health, Working Life and Welfare (Grant no. 2017-01947; 2021-00386).