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Sleep apnea linked to car crashes

Study finds sufferers at double the risk

Melissa Leong, National Post Published: Thursday, February 14, 2008

Roy Antal, CanWest News Service

People with sleep apnea, an often undiagnosed breathing disorder, are three to five times more likely to be in a severe car crash involving injury, researchers in British Columbia have found.

Respirologists at the Vancouver Coastal Health Research Institute and University of British Columbia studied almost 1,600 people and their insurance records and have determined that sufferers of sleep apnea, a condition where the airway collapses during sleep, were at double the risk of being in any collision.

"A lot of sleepiness-related crashes tend to be more severe... where you fall asleep at the wheel and you hit a tree or you cross the median and hit an on-coming car," said study author Dr. Najib Ayas of the Vancouver Coastal Health and associate professor of medicine at UBC.

"Even if you do not fall asleep at the wheel, it has been shown that patients with sleep apnea or sleep deprivation have reduced motor function. It affects coordination, dis-tractability or vigilance."

Of the 10 "extremely serious" motor vehicle crashes -- head-on collisions or those involving pedestrians or cyclists -- noted in the three-year period of the study, eight of the accidents involved patients with sleep apnea. But not all of the people in the study were aware of the potential driving hazards caused by their condition -- self-reported sleepiness was not associated with a higher risk of collisions.

Previous studies have linked sleep apnea to an increased risk of car crashes but Dr. Ayas's study is the largest of its kind and the first to look at the severity of the collisions.

When Eric Diehl was a provincial court judge in Saskatchewan, he said he would see strange accident cases -- motorists "driving off the highway," for example.

"Repeatedly, it came up that the driver had fallen asleep," said the 79-year-old retiree. "I realized that this was a medical condition that they were not aware of ... and I was not aware of mine."

For years, Mr. Diehl was chronically tired and napped during the day. He willed himself to remain alert when driving. His wife complained of his snoring and his disrupted breathing at night.

Tests finally revealed that Mr. Diehl had sleep apnea and was waking up 39 times an hour overnight. He has worn continuous airway pressure equipment (CPAC) since 2004 as treatment.

It is estimated that between five and 10% of people older than 30 suffer from sleep apnea, but the vast majority are undiagnosed. The disorder is also linked to obesity and cardiovascular disease.

One out of eight (or four million Canadians) admit to nodding off at the wheel at least once in the past 12 months, according to the Traffic Injury Research Foundation in 2005. Most motor vehicle licensing boards in Canada require doctors to report diagnosed sleep apnea. Patients can have their drivers' licences temporarily suspended until they are treated.