Police on night shift at greater risk for serious injury

"Not only do more crimes occur during these hours," says John Violanti, "but the calls for service are generally more hazardous and more frequent, which could result in more serious injuries." (Credit: PBS NewsHour/Flickr)

Police officers working the night shift in urban settings are significantly more likely to suffer serious on-the-job injuries than officers on day and afternoon shifts.

A new study shows that independent of age and gender, officers working nights were three times more likely than those on the day shift, and 2.2 times more likely than those on the afternoon shift, to suffer injuries resulting in leaves of more than 90 days.


“Leaves of this length suggest more serious types of injury and indicate that night shift work poses a more significant threat to the life and health of officers than previously assumed,” says epidemiologist John Violanti, a research scientist in the department of social and preventive medicine at the University at Buffalo.

Published in the Scandinavian Journal of Work and Environmental Health, the study assessed the association of daily shift schedules with the occurrence of injury leave and lengths of injury leave from 1994 to 2009 among a cohort of 419 officers from the City of Buffalo Police Department.

“The study results also point to the problems long-term injuries provoke for police managers as long injury absences put a strain on police personnel who must cover for the injured officers,” Violanti says. “This could lead to health problems for them, as well.”

An earlier study found that police on night shifts suffer more on the job injuries overall than their colleagues on day and afternoon shifts.  Violanti says there are several possible explanations for the high injury rates.

“Sleep disturbance and fatigue-related impairment provoked by circadian disruption have been reported in previous studies of night shift workers and have been found to affect the kind of decision making that is required in fast-paced, ambiguous, high-risk police situations.

“Evening and night police shifts are inherently more active than day shifts, too. Not only do more crimes occur during these hours, but the calls for service are generally more hazardous and more frequent, which could result in more serious injuries.”

More hazardous calls

Subjects included 312 men and 107 women with an average age of 43 (range 27–70 years) who had completed the Buffalo Cardio-Metabolic Occupational Police  Stress Study, a cross-sectional study designed to examine associations between physiological biomarkers of stress, subclinical metabolic and vascular disease markers, lifestyle, and psychosocial symptomology among police officers.

In this study, 16 years of day-to-day work records enabled researchers to take into account differences in age and gender across shifts and draw conclusions more accurately than previous research that relied heavily on self-reported data. The shifts considered were: day (8 a.m. to 4 p.m.), afternoon (4 p.m. to 11 p.m.) and night (11 p.m. to 8 a.m.).

The percentages of subjects who worked predominantly on the day, afternoon, and night shifts were 41 percent, 32 percent, and 27 percent, respectively. Participants were followed for the incidence of injuries that occurred while on duty.

Night shift workers were younger and more likely to be male, had fewer years of work experience and were composed of a larger number of patrol officers (84 percent) than were the day shift workers.

Overall 9.6 percent of the officers experienced a long term injury during the 16 year period. After adjustment for age and gender, long-term injury incidence rates were 3.1 times higher in night shift workers than in day shift workers and 2.2 times higher than in afternoon shift workers.

“Research that integrates frequency and duration of injuries would be worthwhile, as would objective measurement, over time, of sleep duration and workload,” Violanti says. “Both would enhance our understanding of the role these factors might play in influencing the risk of police injury.”

Researchers from Washington State University contributed to the study.

Source: University at Buffalo