Associations of Shift Work Patterns With Work-Related Accidents and Dozing Off: Combining Objective Working-Time Registers and Retrospective Questionnaire Data

Introduction: The present study examined associations between different work shift characteristics and self-reported work-related accidents as well as incidents of dozing off at work and while driving to or from work.

Methods: Data were obtained from the payroll register of a Norwegian hospital in 2020 encompassing information on the number of quick returns (<11 hours between shifts), day-, evening-, night-, and long (>9 hours) shifts worked during the last year. These payroll data were subsequently linked to retrospective questionnaire data, collected from 1195 healthcare workers (85.4% females; mean age 38.3 years, SD=12.6) in January 2021. The questionnaire included items about dozing off at work the last month and dozing off while driving to or from work the last year, as well as assessment of work-related accidents resulting in harm to (1) oneself, (2) patients/others, and/or (3) equipment during the last year. A composite score indicating overall harm (all three items) was also computed. Negative binomial regression analyses were performed to investigate the relationship between different work shifts and work-related accidents, controlling demographics, shift work experience, circadian type, and monthly work hours. To correct for multiple testing, the Benjamini-Hochberg procedure with a false discovery rate of 5% was applied.

Results: Number of quick returns during the last year was positively associated with healthcare workers causing harm to themselves (IRR=1.021; 95% CI=1.009–1.034). Number of day shifts were negatively associated with causing harm to patients/others (IRR=0.987; 95% CI=0.981–0.992), equipment (IRR=0.988; 95% CI=0.982–0.994), and overall harm (IRR=0.992; 95% CI=0.988–0.995). Number of night shifts were positively associated with dozing off at work (IRR=1.005; 95% CI=1.002–1.008) and while driving to or from work (IRR=1.007; 95% CI=1.003–1.010). Lastly, the number of evening shifts was negatively associated with causing harm to patients/others (IRR=0.989; 95% CI=0.982–0.996).

Conclusion: Number of quick returns was associated with increased risk of causing harm to oneself, while number of day shifts was associated with a lower risk of overall harm, harm to patients/others, and to equipment. The number of evening shifts was associated with a lower risk of causing harm to patients/others, whereas number of night shifts was associated with a higher risk of dozing off at work and while driving to or from work. A novel element and strength of the present study is that it combines objective working-time registers with subjectively reported work-related accidents. A limitation concerns the challenge of adjusting for medical operations/workload variations across shifts, potentially influencing risk estimates, especially during night shifts. Future studies should aim to measure and adjust for relevant occupational and operational confounders.

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Artikel online veröffentlicht:
08. Oktober 2025