Objectives: The purpose of this study was to use objective registry data to prospectively investigate the effects of quick returns (QR, <11 hours of rest between shifts) and night shifts on sick leave.
Methods: A total of 1538 nurses (response rate =41.5%) answered questionnaires on demographics and personality and provided consent to link this information to registry data on shift work and sick leave from employers' records. A multilevel negative binomial model was used to investigate the predictive effect of exposure to night shifts and QR every month for 1 year, on sick leave the following month.
Results: Exposure to QR the previous month increased the risk for sick leave days (incidence rate ratio (IRR)=1.066, 95% CI 1.022 to 1.108, p<0.01) and sick leave spells (IRR=1.059, 95% CI 1.025 to 1.097, p<0.001) the following month, whereas night shifts did not. 83% per cent of the nurses experienced QR within a year, and on average they were exposed to 3.0 QR per month (SD=1.6). Personality characteristics associated with shift work tolerance (low on morningness, low on languidity and high on flexibility) were not associated with sick leave, and did not moderate the relationship between QR and sick leave.
Conclusions: We found a positive linear relationship between QR and sick leave. Avoiding QR may help reduce workers' sick leave. The restricted recovery opportunity associated with QR may give little room for beneficial effects of individual characteristics usually associated with shift work tolerance.
Keywords: Quick returns; Sick leave.
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