Forty per cent of police officers have a sleep disorder, which could increase the risk of accidents or death, a new study suggests.

"A large proportion of police officers in our sample showed a positive sleep disorder screening result, which was associated with adverse health, safety, and performance outcomes," the authors wrote.

Researchers at Brigham and Women's Hospital Boston examined the risk of sleep disorders — and the negative consequences such as disorder can have — among 4,957 police officers in Canada and the U.S between July 2005 and December 2007. The average age of the police officers was 38.5 years, with12.7 years the average length of service.

Of the 4,957 participating officers who were either assessed in person or via an online questionnaire, 2,003 or 40.4 per cent tested positive for at least one sleep disorder. And 1,666 of the total group screened positive for obstructive sleep apnea (OSA), a sleep disorder which causes the airway to close during sleep, leaving a person choking or gasping for breath.

The study found 281 screened positive for moderate to severe insomnia and 269 with shift work sleep disorder, a condition in which a person wakes multiple times a night because their internal clock is disturbed.

The researchers point out that sleep disorders can severely affect a person’s quality of life and ability to function. They found that of those police officers who tested positive for a sleep disorder:

• 10.7 per cent also suffered from depression.
• 34.1 per cent reported they had burnout.
• 20 per cent said they fell asleep while driving.

"Positive OSA screening was also associated with diagnosis of diabetes, cardiovascular disease, and high caffeine consumption," reads the study.

Among the entire group of study participants — those who had sleep disorders and those who did not — sleepiness scores were high. In the group, 45.9 per cent reported they had dozed off while driving, with 56.9 per cent reporting they had fallen asleep driving at least once or twice a month. And 13.5 per cent said they fell asleep at least one to two times a week while driving.

Among those with sleep disorders, the study also found a higher incidence of:

• Administrative errors.
• Committing safety violations due to fatigue.
• Being uncontrollably angry on the job.
• Having frequent absences.
• Falling asleep during meetings.

The study is to be published in the Wednesday issue of the Journal of the American Medical Association.