Aug 15 2006
A large study of commercial truck drivers has revealed that those who have chronic sleep deprivation and sleep-related breathing problems may be a hazard on the road.
Truck drivers who have severe sleep apnea or who sleep less than five hours each night while at home are more likely to suffer from sleepiness, performance impairment and decreased task vigilance while behind the wheel.
Sleep apnea is a disorder in which the tissues at the back of the throat temporarily collapse, causing a brief pause in breathing until the brain rouses the person from deep sleep.
This can happen dozens of times during the night, and often leads to poor sleep quality and daytime drowsiness.
Allan L. Pack, M.B., Ch.B., Ph.D., and six colleagues from the University of Pennsylvania studied 406 commercial drivers, 247 of whom were at high risk for sleep apnea and 159 at lower risk for sleep impairment.
Dr. Pack says approximately 5,600 people are killed in crashes involving commercial trucks in the United States every year and falling asleep while driving is an important factor in serious crashes involving commercial vehicles.
According to the authors, the reason is because many truckies suffer from chronically insufficient sleep or sleep apnea.
Mild to moderate sleep apnea was defined as from 5 to 30 temporary breathing pauses per hour of sleep, while severe sleep apnea was defined as more than 30 breathing pauses per hour.
The researchers also found that 77 percent of those with mild sleep apnea and 56 percent of with moderate sleep apnea did not have what could be termed "pathologic sleepiness" as a result of their problem.
To assess sleepiness the authors a range of standard tests in a sleep laboratory.
Dr. Pack says of the 406 drivers tested, 93.3 percent were male and were over 45 years old, 81.6 percent were employed as drivers of a commercial vehicle and all had a commercial driver's license.
The researchers found that 28 percent of truck drivers were found to have at least mild sleep apnea, with almost 5 percent having their breathing interrupted 30 or more times per night.
This latter group showed signs of excessive daytime sleepiness, being more likely than drivers without sleep apnea to fall asleep within 5 minutes of hitting the pillow.
Similarly, drivers who normally slept less than 5 hours per night were more likely to be exhausted during the day, and they performed more poorly on tests of alertness and reaction than their better-rested counterparts.
The authors suggest, because drowsy driving is a major cause of collisions involving commercial vehicles, that drivers need to be routinely screened for both sleep apnea and for the impaired performance that can come with chronic sleep deprivation.
They suggest the Federal Motor Carrier Safety Administration should develop plans to implement ways of identifying "sleep-impaired" drivers in order to ensure they receive therapy and to promote increased sleep duration among commercial drivers.
The study is published in the American Journal of Respiratory and Critical Care Medicine, August 2006.
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