May 22, 2007 - Bad enough by itself, sleep apnea can lead to worse things --
such as serious car wrecks, heart disease, diabetes, and pregnancy complications.
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
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
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."
All sleep apnea patients appeared to be at risk of crashing their cars. The
problem wasn't limited to those with severe apnea.
"It didn't matter how severe your sleep apnea was. We found that you still
have the same increased risk even if you have mild sleep apnea," Mulgrew
And patients seemed unable to tell when they were at greater risk. Patients
who said they drove even when they felt sleepy were no more likely than other
sleep apnea patients to wreck their cars.
The results of the study were so striking that Mulgrew now carefully asks
his sleep apnea patients about their driving histories and about any "near
misses" they might be having. He is much more likely to recommend the most
apnea treatment -- a continuous positive air pressure or CPAP device -- to
patients with driving problems, even if their sleep apnea is relatively