Shift work and the incidence of injury among police officers

Background: Police officers may be injury prone due to fatigue, erratic work hours, and insufficient sleep. This study explored injury incidence among police officers across shifts. Methods: Day-to-day shift data from computerized payroll records (1994-2010) were available from a mid-sized urban police department (n=430). Sleep duration, shift activity level, returning to work after days off, and injury incidence over time were also examined. Results: Age-adjusted incidence rate ratio (IRR) for injury on the midnight shift was 72% larger than the day shift (IRR=1.72; 95% CI=1.26-2.36) and 66% larger than the afternoon shift (IRR=1.66; 95% CI=1.23-2.25). Injury incidence for the first day back on the midnight shift was 69% larger than day shift (IRR=1.69; 95% CI=1.23-2.32) and 54% larger than the afternoon shift (IRR=1.54; 95% CI=1.36-1.76). High activity level combined with midnight shift work put officers at increased injury risk (IRR=2.31; P=0.0003). Probability of remaining free of injury was significantly higher for day shift than midnight shift (P<0.0001). Conclusions: Higher injury risk was associated with night shift work in police officers. Night shift combined with high work activity was strongly associated with injury risk. There was a significantly higher probability of not being injured on day compared to midnight or afternoon shifts.