The findings point to a growing awareness that sleep apnea contributes to a wide range of public health problems. All of the studies were reported at this week's annual meeting of the American Thoracic Society in San Francisco.
Obstructive sleep apnea is caused by a narrowing or collapse of throat tissues during sleep. Blood-oxygen levels plummet, and the body responds by sending out a flood of hormonal emergency signals. The sufferer wakes, sometimes 30 or more times an hour, his or her body in full "flight or fight" mode.
"That does a number on your sympathetic nervous system," Yale researcher Nader Botros, MD, MPH, tells WebMD. "It is as if you were waked at night because a saber-toothed tiger was chasing you."
This obviously prevents a good night's sleep and results in daytime sleepiness. But it also means that repeated stress signals take their toll. The new studies assess that toll.
Raw data suggest that sleep apnea raises the risk that a person will be involved in a motor vehicle accident. New data not only confirm this finding, but show that sleep apnea patients are at very high risk of serious, life-threatening car wrecks.
Alan Mulgrew, MD, and colleagues at the University of British Columbia in Vancouver compared the claims and accident records of 800 patients with confirmed sleep apnea with those of 800 people who did not have sleep apnea.
Over the three years before their diagnosis, the sleep apnea patients were nearly five times more likely to have serious car crashes than were other drivers. Serious car crashes were defined as those with injury or head-on crashes.
Many things contribute to driving risk. So Mulgrew's team carefully adjusted for things such as caffeine and alcohol consumption and shift work.
"No matter what you try to account for, sleep apnea patients still have these serious crashes in threefold excess," Mulgrew tells WebMD. "When we looked at the small number of truly awful crashes -- head-on collisions and collisions with pedestrians or cyclists -- 80% of the crashes of that kind were in sleep apnea patients."