Long Hours, Little Sleep Contribute to Drowsy Driving Crashes, Study Shows

21 December 1999
Long Hours, Little Sleep Contribute to Drowsy Driving Crashes, Study Shows
    WASHINGTON, Dec. 21 -- In the first-ever study of its kind,
the AAA Foundation for Traffic Safety and the University of North Carolina
Highway Safety Research Center (HSRC) studied hundreds of sleep and fatigue-
related car crashes to identify the driver behavior that caused them.
    Factors strongly associated with having a drowsy driving crash included
sleeping less than six hours per night, being awake for 20 hours or longer,
working more than one job and/or working night shifts, and frequent driving
between midnight and 6 a.m. With 35 million drivers about to travel for the
holidays, this issue is particularly timely.
    "Previous studies about drowsiness and driving were done in a laboratory,"
says David K. Willis, President of the AAA Foundation for Traffic Safety.
"This is the first time anyone has looked at real-world crashes to see what
happens. And what happens is that drivers who have had six or less hours of
sleep or who often drive between midnight and 6 a.m. put themselves at very
high risk."
    The study was performed by Dr. Jane Stutts of the HSRC with Drs. Bradley
Vaughn and Jean Wilkins of the UNC School of Medicine. Researchers who used
police crash reports and driver records to identify and interview 1,400
drivers. The sample included four groups: drivers who fell asleep, drivers who
were fatigued, drivers who crashed for non-sleep reasons, and a control group
of drivers who had not had a crash in three years. The researchers
administered a detailed questionnaire about the drivers' work schedules, sleep
habits, quality of sleep, amount of driving, and the circumstances surrounding
their crash.  Drivers were also asked questions to assess their present levels
of sleepiness.
    Large differences were found among the groups. Sleep and fatigue crash
drivers had been awake longer and had slept less -- just a fifth of them
reported getting 8 or more hours of sleep before the crash, compared with
nearly half of the control group. Drivers in sleep and fatigue crashes were
also more likely to deal with their drowsiness once they were on the road
rather than by planning ahead and taking precautions such as getting enough
sleep or using caffeine.
    The study indicated that many drivers do not know how sleepy they are.
Around half the drivers in sleep-related crashes said they did not feel even
moderately drowsy before they crashed. "People need to think about sleep even
when they don't feel tired," Willis says. "Driving with your eyes closed can
kill you."
    The AAA Foundation for Traffic Safety is a not-for-profit charitable
organization funded by donations from AAA and CAA clubs and members. It is
devoted to preventing crashes and saving lives through research and education
in the field of traffic safety. The full study may be found on the AAA
Foundation's web site, http://www.aaafoundation.org.