To tell you the truth, I thought I was fine." This is what 29-year-old Jamie Summerlin told police and researchers at the University of North Carolina (UNC) Highway Safety Research Center after she dozed off behind the wheel of her car, sending it veering across the median of the road and smashing into a parked truck on the opposite side of the street.
Summerlin, a third-shift worker at a plastic manufacturing company in Harrisburg, N.C., was making her daily 27-mile commute home. She recalls feeling sleepy prior to the crash and pulling into a restaurant parking lot where she slept for a few minutes before deciding she felt clear-headed enough to drive home.
"I went about three blocks, turned right, and I can't tell you anything from there. That's when I had the wreck," she told researchers.
At the time of the accident, Summerlin was working several extra hours per week and attributes working third shift as the primary cause of her exhaustion. "It doesn't matter how much sleep you get on third shift, you're still sleepy and exhausted. Your body's not used to something like that, and it just can't get used to it."
Summerlin, who now works first shift, told researchers her crash experience often makes her wonder about the physical condition of other drivers on the road. "Now whenever I'm going to work, I wonder who is getting off work and may be in the same condition I was in that morning. It's something to think about."
The National Highway Traffic Safety Administration (NHTSA) agrees. Experts believe driver fatigue ranks higher than driver misbehavior, inattention and even poor judgment as the most common cause of human error behind the wheel. Driving too fast, running off the road or out of the lane of traffic, and failing to yield the right-of-way are the top three crash-related factors cited by the Federal Motor Carrier Safety Administration.
Approximately 100,000 police-reported crashes involve drowsiness or fatigue as a principal causal factor each year. At least 71,000 people are injured in those crashes, costing U.S. consumers $12.5 billion annually.
Studies consistently correlate driver alertness and performance. Driver fatigue has particularly devastating consequences because of its ability to impair drivers from making sound, split-second and, often, life-saving decisions -- in most cases before they even have a chance to realize it.
One-fourth of the drivers involved in sleep-related crashes interviewed as part of a UNC study released in March said they had driven drowsy more than 10 times in the past year, and more than half reported not feeling even moderately drowsy before they crashed, according to Jean Wilkins, project co-investigator at the UNC School of Medicine.
"Driving while sleepy is not a new experience for many drivers. Many of them think that drowsy driving is no big deal. They think they can handle it, that they can force themselves to stay awake. But this just isn't true," Wilkins said. "Many of us would never think about driving drunk, but by driving when we're sleep-deprived, we put ourselves and others at risk of a crash that is as severe as, or more severe than, an alcohol-related crash."
In fact, another study released in May by researchers at the Stanford University Medical Center and the Washington University School of Medicine in St. Louis indicates that sleep, or lack there of, impacts reaction time and driving performance as much as alcohol, making sleep-deprived drivers one of the biggest hazards on the highways.
"This study demonstrates that driving while sleepy is at least as dangerous as, if not more dangerous than, driving while intoxicated," said Nelson Powell, MD, co-director of the Stanford Sleep Disorders Clinic and Research Center, located in Stanford, Calif.
As part of the study, published in the May issue of Laryngoscope, researchers studied 16 healthy, adult drivers to ascertain changes in reaction times and driving performance when they were either sleep-deprived or alcohol-impaired. During the first round of the study, participants drove a 1.4-mile General Motors performance course in Arizona while in a fully rested, nonsleepy state. On the course, drivers encountered several hazards and were judged, in part, by their reaction to them.
After the initial round, the volunteers were split into three groups to repeat the tests. The first group was tested after spending one night without sleep, the second after sleeping for no more than two hours for seven consecutive nights and the third after consuming alcohol.
As expected, researchers found that reaction times and driving performance significantly diminished during the second set of tests. Researchers were surprised to find little difference in reaction time and driving performance between the sleep-deprived and the alcohol-impaired groups.
Powell noted that the average reaction time was 294 milliseconds for the alcohol-impaired group and 300 milliseconds for the sleep-deprived group. That might be less than the time it takes the eye to blink, but long enough to cause a devastating accident, he said.
In the Driver's Seat
According to UNC's study, drivers who work night shifts, long hours or more than one job are at an increased risk for being involved in a crash caused by fatigue or falling asleep while driving. The study was based on interviews with 1,400 drivers, 529 of whom had sleep-related crashes, 467 who had nonsleep-related crashes and 407 who had not been in an accident in more than three years.
Other factors researchers associate with being at risk for having a sleep-induced accident:
- Sleeping less than six hours per night,
- Being awake for 20 hours or more,
- Frequent driving between midnight and 6 a.m., and
- Irregular work or rest schedules.
"We found that drivers in sleep- and fatigue-related crashes were four to five times more likely than the drivers in the other crash group to work night-shift jobs," said Jane C. Stutts, Ph.D., principal investigator for the UNC Highway Safety Research Center. "Working 60 or more hours a week also increased drivers' risk of falling asleep at the wheel, and drivers in sleep-related crashes were nearly twice as likely as drivers in the control crash group to work more than one job."
The UNC study, funded by the AAA Foundation for Traffic Safety, also found that drivers in the study who had not been involved in crashes had considerably different profiles than those who had. For example, drivers who had not been in an accidents in three years were older and much less likely to be employed. They were also more likely to be female and reported driving less.
"What this demonstrates is that the vast majority of people in our study who crashed as a result of driving while drowsy either got too little sleep on a routine basis and built up what sleep researchers describe as 'sleep debt,' or they got far too little sleep before trying to drive," she said. "In many cases, the people involved in these crashes were just the average 'driver next door' who happened to be putting in extra hours at work, adjusting to a new baby in the household, staying out late for a party or trying to make it back home after an out-of-town trip."
Because sleepy drivers are likely to rely on behaviors that have not been proven effective in preventing accidents, such as opening windows or turning up the radio, it is important for employers to educate their employees -- particularly night shift, overtime or rotating shift workers -- on how toadjust to circadian rhythm changes and how to prevent and cope with drowsy driving.
According to NHTSA, periods of work longer than eight hours have been shown to impair task performance and increase crashes, and driver performance has been found to be worse with a 12-hour, four-day workweek schedule than an eight-hour, six-day workweek. For that reason, in jobs with extended hours, employers should schedule work and rest periods to conform to circadian rhythms in an effort to promote better sleep and performance.
Another effective measure NHTSA recommends is allowing and facilitating napping for night-shift workers. Employers should also instruct their employees to:
- Plan time for uninterrupted, restorative sleep;
- Create a quiet, cool, dark environment that facilitates sound sleep;
- Try to sleep during the same hours each day;
- Avoid driving home from work while sleepy by getting a ride from a family member, taking a cab or napping before heading home; and
- Consume caffeine equivalent to two cups of coffee to improve alertness for a short period in order to get them home safely after their shift.
Many of these suggestions are merely remedial approaches to existing sleepiness, experts admit. By far, the best solution is to prevent drowsiness with adequate sleep before driving. If all else fails, Powell said, employees need to be constantly reminded of one thing: "They need to stay away from their cars when they're tired."