There’s a reason you shouldn’t get behind the wheel after a long night. Data suggests that 15 to 33 percent of fatal—fatal—car rashes are caused by drowsy drivers, and new research out of the Perelman School of Medicine at the University of Pennsylvania shows that those who regularly sleep less than six hours per night, on average, are the most likely to experience drowsy driving, even when they’re supposedly “rested.”
The study, published in Accident Analysis and Prevention, found that subjects who self-reported sleeping six hours a night or less were about twice as likely as seven-hour sleepers to report drowsy driving in the past month, and those reporting five hours of sleep or less were four times as likely.
“Falling asleep at the wheel is a major cause of road accidents. It might even be more of a problem than drunk driving, since it is responsible for more serious crashes per year," said study author Michael Grandner, Ph.D., a member of the Center for Sleep and Circadian Neurobiology. “We already know that people who are sleep deprived in the laboratory have impaired driving performance, but we haven't been able to better define what sleep profiles and patterns put drivers in the general population at the highest risk.”