• police;
  • occupational injury;
  • shift work;
  • work hours;
  • fatigue;
  • sleep;
  • activity levels



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.


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.


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).


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. Am. J. Ind. Med. 55:217–227, 2012. © 2011 Wiley Periodicals, Inc.