August 2006 - Lack of Sleep Affects the Performance of Many Commercial Drivers

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 researchers at the University of Pennsylvania School of Medicine. 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.

As the basis for the study, the researchers used information collected from an earlier study on the prevalence of sleep apnea among commercial vehicle drivers. This earlier study was funded by the Federal Motor Carrier Safety Administration (FMSCA) and the American Trucking Associations. The new findings build upon the research by looking at the effect that inadequate sleep and sleep apnea had on driving performance.

The researchers focused on 247 drivers that had been identified as being at a high risk for sleep apnea. Their behavior was compared against 159 drivers at low risk. The researchers analyzed the information collected to evaluate the role of short sleep durations and sleep apnea on the subjective sleepiness of the drivers, objective sleepiness, and neurobehavioral functioning. The functioning tests involved driver attention, reaction time, and "lane tracking ability."

When the results were compiled, investigators discovered:

• 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.
• 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 only 10 percent of drivers who got more than eight hours of sleep regularly.
• About 60 percent of the drivers with severe sleep apnea had two or three impairments.

Based upon these results, the researchers concluded that addressing impairment in commercial drivers requires addressing both insufficient sleep and sleep apnea.

The study results were published in the August 15th issue of the American Journal of Respiratory and Critical Care Medicine. The article is titled, "Impaired Performance in Commercial Drivers: Role of Sleep Apnea and Short Sleep Duration." An abstract of the article is available at http://ajrccm.atsjournals.org/cgi/content/abstract/174/4/446.

A summary of the earlier study on the prevalence of sleep apnea in commercial vehicle drivers is available from the FMCSA Web site at www.fmcsa.dot.gov/facts-research/research-technology/tech/Sleep-Apnea-TechBrief.pdf. The Web site also provides information for purchasing the complete study from the National Technical Information Service (NTIS).

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