(Philadelphia, PA) - 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. The study results are
published in the August 15th issue of the American Journal of
Respiratory and Critical Care Medicine.
This study is among the largest and most comprehensive studies
of truck drivers and fatigue ever done. Penn 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
Allan Pack, MB, ChB, PhD, who headed the study,
said the tired truck drivers had impaired performance similar to
that of drivers who are legally drunk. “We identified some
very impaired people,” said Pack, a sleep expert who directs
Penn’s Center for Sleep and Respiratory Neurobiology.
Nearly five 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. “There are daytime neurobehavioral performance
impairments that are found commonly in commercial drivers, and these
are more likely among those who get an average of five or less hours
of sleep a night and those who suffer from severe obstructive sleep
apnea,” the researchers concluded.
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 five 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’s 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
- 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.
The results of this study are published in the August 15th issue
of the American Journal of Respiratory and Critical Care Medicine.
You can access the journal on-line.
The article is titled, “Impaired Performance in Commercial
Drivers: Role of Sleep Apnea and Short Sleep Duration.” Other
Penn researchers who worked on the study were: Greg Maislin; Bethany
Staley; Frances Pack and David Dinges. William Rogers, formerly
of the Trucking Research Institute, American Trucking Associations
as well as Charles F. P. George of the University of Western Ontario
were also involved.
The research was funded through a contract from the Trucking Research
Institute, American Trucking Associations -- that was funded by
the Federal Motor Carrier Safety Administration. The National Institutes
of Health also provided funding.
This was a single site study conducted at Penn.
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