Researchers found that 13 percent of truckers routinely skimped on sleep, and nearly 5 percent had severe sleep apnea — and that those truckers performed worse on reaction and driving tests.
In fact, some truckers tested as poorly as people who have taken the same tests after drinking alcohol for other studies.
In their study, the University of Pennsylvania's Allan Pack, M.B., Ch.B., Ph.D., and colleagues looked at 406 licensed truck drivers, most of whom were still working as drivers, between 1996 and 2000.
"We identified some very impaired people," Pack says, in a university news release.
His study appears in the August issue of the American Journal of Respiratory and Critical Care Medicine.
The researchers mailed surveys to about 4,800 people with commercial driver's licenses living near Philadelphia.
Around 1,300 truckers completed the surveys, and Pack's team invited them to the University of Pennsylvania's sleep lab for testing.
A total of 406 drivers agreed. Those truckers rated their sleepiness, spent a night at the sleep lab to check for sleep apnea, kept sleep diaries, and wore activity monitors for a week.
Sleep apnea is when breathing briefly stops during sleep.
They also took tests of their reaction time and a simulated driving test. And they were tested to see how easily they fell asleep (a fall asleep test).
After testing the truckers, the researchers found that:
Those with severe sleep apnea stopped breathing more than 30 times while asleep during their night at the sleep lab.
Those with mild sleep apnea stopped breathing at least five times but fewer than 15 times.
When someone with sleep apnea stops breathing during sleep, they wake up to breathe, though they may not realize it.
That makes them sleepier during the day and more likely to fall asleep at inappropriate and unexpected times.
Truckers with sleep apnea didn't always report feeling sleepy, even though they tended to nod off during the fall asleep test, the study shows.
As Bad as Drinkers
Many of the truckers scored as poorly on the tests as people have after drinking alcohol. That was true of:
The poorest performance was generally seen in truckers who routinely got less than five hours sleep and those with severe sleep apnea, although scores varied, the researchers note.
The findings might not apply to all truckers. It's possible those who skipped the study would have scored better or worse than those who chose to take part.
It's also not clear if the results reflect crash risk in the real world.
"There are no data that currently show an association between impairments in the tests we performed and crash risk in commercial drivers," the researchers write.
One of Pack's colleagues formerly worked at the American Trucking Association's Trucking Research Institute, the journal notes.
SOURCES: Pack, A. American Journal of Respiratory and Critical Care Medicine, Aug. 15, 2006; vol 174: pp 446-454. National Highway Traffic Safety Administration: "Driving When You Have Sleep Apnea." News release, University of Pennsylvania. News release, American Thoracic Society.
By Miranda Hitti
Reviewed by Louise Chang, M.D.
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