Sleeping for less than 6 hrs at night leads to drowsy driving in mornings

New data suggests that 15 to 33 percent of fatal car accidents are caused by drowsy drivers, but very little research has addressed what factors play a role in operating a vehicle in this impaired state.

A new research from the Perelman School of Medicine at the University of Pennsylvania has revealed that short sleepers, those who sleep less than six hours per night on average, are the most likely to experience drowsy driving, even when they feel completely rested.

"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," corresponding study author Michael Grandner, PhD, instructor in Psychiatry and member of the Center for Sleep and Circadian Neurobiology, said.

"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," he said.

Using the Behavioral Risk Factor Surveillance System (BRFSS) data, Grandner and colleagues found that people who self-reported sleeping 6 hours or less (short sleepers) on average were about twice as likely as 7-hour sleepers to report driving drowsy in the past 30 days, and those sleeping 5 hours or less (very short sleepers) were nearly 4 times as likely.

They also examined the data on the subset of short and very short sleepers who reported that they always receive sufficient sleep, finding that these people are still 3 times as likely to report drowsy driving in the past 30 days. This means that short sleepers, even if they feel fully rested, are more likely to drive drowsy.

The study is published in the journal Accident Analysis and Prevention.