While driving drunk or being immersed in texting grabs headlines, another danger involves operating a motor vehicle while under the influence of sleep deprivation.
A new study from the AAA Foundation for Traffic Safety shows “there is a significantly elevated crash risk” for drowsy drivers.
Drowsy drivers are defined as those getting fewer than the recommended seven hours or more of sleep in a day, those getting an hour or more less sleep than usual, as well as those who are chronically sleep deprived, said Robert Sinclair Jr., manager of media relations for AAA Northeast.
What’s more, the crash risk increases exponentially as the number of hours of sleep deprivation rises.
Drivers who reported getting just five to six hours of sleep in the previous 24 hours had 1.9 times the crash rate of drivers who had the recommended amount of shut-eye, the report found. Make that 4.3 times the crash rate for those getting four to five hours of sleep, and for those pushing it with fewer than four hours — an 11.5 times higher risk, the study found.
Indeed, functioning with insufficient sleep can have a direct effect on key skills needed for those driving down a highway, said Dr. Harly Greenberg, medical director of Northwell Health’s Center for Sleep Disorders in Great Neck.
“Acute sleep deprivation has a strong impact on human performance, in particular vigilance,” he said, with “the ability to stay vigilant in a monotonous situation impaired and quite acutely.” The ability to react to some changing stimulus is also affected, he said.
As for those who are also chronically sleep deprived — meaning going night after night with an hour or two sleep deficiency — studies have shown those people function as poorly as those who’ve been awake all night long, Greenberg said.
The AAA study found that drivers who reported getting just four to five hours of sleep a day on a regular basis had 5.4 times the crash rate of drivers getting seven hours or more.
The study sample included 7,234 drivers who were involved in 4,571 crashes from July 3, 2005, to Dec. 31, 2007. In addition to regular police attention, those incidents were further investigated as part of a study by the U.S. Department of Transportation, with drivers’ recent sleep among the assessments.
“Not getting enough sleep is extremely dangerous” and operating on less than four hours of shut-eye is akin to those driving while alcohol impaired, Sinclair said.
The study found those with just four to five hours of sleep saw a similar crash risk as that “associated with driving with a blood alcohol concentration equal to or slightly above the legal limit for alcohol in the U.S.” That risk is “much greater” for those functioning on even fewer hours of sleep.
The AAA research does have some limitations, Sinclair said, as the data did not include crashes from midnight to 6 a.m., with other reports indicating drowsy driving can be more prevalent in those overnight hours. Also, drivers “self-reported” the data related to their sleep, he said. A National Highway Traffic Safety Administration spokesman said Tuesday the agency soon plans to “issue a national strategy to combat drowsy driving.”
“Not everyone drinks and drives or texts while driving, but everyone gets tired, and far too often drivers are putting themselves and others at risk by getting behind the wheel without the sleep they need,” said Bryan Thomas, director of communications with the National Highway Traffic Safety Administration.
Earlier AAA research estimates that drowsy drivers are involved in 13 percent of crashes in the United States that lead to a person or people being admitted to a hospital, as well as 16 percent to 21 percent of fatal crashes, the report said.