Even when they say they feel rested, people who sleep fewer than six hours per night on average are the most likely to drive drowsy.
Federal data suggest that drowsy drivers cause 15 to 33 percent of fatal automobile crashes, but very little research has addressed what factors play a role in operating a vehicle in this impaired state.
The study is published in the October issue of the journal Accident Analysis and Prevention.
“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,” says corresponding study author Michael Grandner, instructor in psychiatry and member of the Center for Sleep and Circadian Neurobiology at the University of Pennsylvania.
“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.”
Previous research on drowsy driving has utilized results from laboratory experiments, but the new study, using data from the CDC’s 2009 Behavioral Risk Factor Surveillance System (BRFSS), evaluated individuals in the general population.
BRFSS is an annual, state-based, random digit-dialed telephone interview survey of adults aged 18 years and older from all over the US, conducted by the CDC. It is the world’s largest telephone survey, designed to monitor health-related behaviors in the general population.
Using the BRFSS data, Grandner and colleagues found that people who self-reported sleeping 6 hours or fewer (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 fewer (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 National Heart, Lung and Blood Institute, the National Institute of Environmental Health Sciences, and the Institute for Translational Medicine and Therapeutics, via the Penn CTSA and the National Institute for Occupational Health and Safety/Centers for Disease Control, supported the research.
Source: University of Pennsylvania