Truck drivers who routinely get too little sleep or suffer from sleep apnea show signs of fatigue and impaired performance that can make them a hazard on the road, according to a major new study by researchers at the University of Pennsylvania School of Medicine.
Tennesseans and others in the Mid-South who depend on Interstate 40 for regular travel should be aware of the dangers of sleep deprived truck drivers.
The study results are published in the Aug. 15 issue of the American Journal of Respiratory and Critical Care Medicine. The study is among the largest and most comprehensive studies of truck drivers and fatigue ever done.
Researchers examined 406 truck drivers and found that those who routinely slept less than five hours a night were likely to fare poorly on tests designed to measure sleepiness, attention and reaction time and steering ability.
Drivers with severe sleep apnea, a medical condition that causes a poor quality of sleep, also were sleepy and had performance impairment.
The physician who headed the study said the tired truck drivers had impaired performance similar to that of drivers who are legally drunk.
Nearly 5 percent of the truckers had severe sleep apnea (a condition in which someone stops breathing often during sleep), and about 13 percent of the drivers got fewer than five hours of sleep a night on a regular basis.
To measure the impact of fatigue on driver performance and safety, Penn researchers sent questionnaires to 4,826 truck drivers who had commercial licenses and lived within 50 miles of the Penn sleep centers. After getting complete responses from 1,329 drivers, they focused on 247 drivers at high risk for sleep apnea and 159 drivers at low risk.
The truck drivers, almost all men and on average 45 years old, were given wrist motion detection devices to measure how much they slept during a week. They then were put through a battery of tests at the sleep center. The drivers were monitored in the sleep lab while they slept to see if they had sleep apnea. About 28 percent of the drivers were found to have some degree of sleep apnea, with nearly five percent of them having a severe case.
Three tests were then given to measure daytime sleepiness and performance. The drivers were put in a dark room and observed to see how long it took them to doze off. Drivers who logged less than five hours of sleep dozed-off more quickly than those who got seven to eight hours of sleep. Drivers with severe sleep apnea also dozed-off more rapidly. A lab test to analyze attention and reaction time and another to gauge “lane tracking ability" also turned up performance impairment among the sleep-deprived.
When the results were compiled, investigators discovered:
- Just over 5 percent of drivers showed impairment on all three performance-related tests.
- Nearly 60 percent did not fare well by at least one measure.
- About half of the drivers who got less than five hours of sleep had two or three impairments. That is compared to 10 percent of driver who got more than eight hours of sleep regularly.
- Likewise, about 60 percent of the drivers with severe sleep apnea had two or three impairments.
According to the journal article, about 5,600 people are killed each year in the U.S. in crashes involving commercial trucks. Many of the crashes happen when the driver falls asleep at the wheel. Penn researchers are now suggesting specific steps for the Federal Motor Carrier Safety Administration to take to improve safety for everyone on our roads:
- Develop strategies to identify impaired drivers through objective testing.
- Implement programs to identify and test drivers with severe sleep apnea and monitor that they stick to their treatment.
- And introduce programs to assess and promote longer durations of sleep among commercial drivers.