Drivers Beware: Crash Rate Spikes With Every Hour Of Lost Sleep

Dec 6, 2016
Originally published on December 6, 2016 5:55 pm

Traffic safety officials regularly warn us of the risks of driving while drunk or distracted.

But Americans still need to wake up to the dangers of getting behind the wheel when sleepy, according to a recent study of crash rates.

A report released Tuesday by the AAA Foundation for Traffic Safety suggests that drivers who sleep only five or six hours in a 24-hour period are twice as likely to crash as drivers who get seven hours of sleep or more.

And the less sleep the person behind the wheel gets, the higher the crash rate, according to the findings. For instance, drivers in the study who got only four or five hours of shut-eye had four times the crash rate — close to what's seen among drunken drivers.

"If you have not slept seven or more hours in a given 24-hour period, you really shouldn't be behind the wheel of a car," says Jake Nelson, director of Traffic Safety Advocacy & Research for AAA.

Prior research has shown that about 20 percent of fatal accidents in the U.S. involve a drowsy driver. Last year, a total of 35,092 people died in auto accidents in the U.S, according to data from the National Highway Traffic Safety Administration. This was a 7.2 percent increase in fatal crashes over 2014.

The foundation based its current report on data from the NHTSA's National Motor Vehicle Crash Causation Survey. The data were drawn from police-reported crashes in which at least one vehicle had to be towed away from the accident scene, and/or emergency medical services were summoned. Drivers involved in these crashes were asked to report how much sleep they got in the 24-hour period preceding the crash.

As a nation, we tend to give shut-eye short shrift, many studies find. More than one in three Americans don't get enough sleep on a regular basis, according to an analysis by the Centers for Disease Control and Prevention. In addition to highway accidents, sleep deprivation has been linked to weight gain and depression. Sleep specialists generally recommend that adults get between seven and nine hours of sleep per night.

"Sleep is a bigger priority for me now," says Karen Roberts, a nurse in Cincinnati who fell asleep behind the wheel several years ago after working an overnight shift. She crossed the double line while driving home and caused an accident. Sleep is not a luxury, Roberts now knows. "It's a necessity," she tells Shots.

Roberts says she did consider stopping for a soda or another pick-me-up that night as she was driving home. "I remember feeling so tired," she says. But she was only a few miles from home and convinced herself that she could power through the fatigue.

"It happens in an instant," Roberts says. "I struck someone head on."

Fortunately, the driver in the other car walked away with only minor injuries. Roberts says she recovered from her own injuries but has continued to struggle with health problems related to the crash, including headaches.

Nelson has this tip for drivers: If you're feeling sleepy, stop and take a nap.

"Taking a 10 to 20 minute nap every couple of hours on a long drive has huge safety benefits in terms of your ability to drive without crashing," he says.

It's also possible to catch up on missed sleep — to a point. If you get only five hours of sleep during a night, you can make up the deficit by sleeping two hours during another part of the day.

"As long as you get seven to eight hours of sleep within a 24-hour period before you get behind the wheel of a car," Nelson says, "you're OK."

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If you're planning a big road trip for the holidays, make sure you get plenty of sleep first. A new study from the AAA Foundation for Traffic Safety finds drowsy driving can be as risky as drunk driving. Missing just a few hours of sleep significantly increases the risk of crashing. NPR's Allison Aubrey reports.

ALLISON AUBREY, BYLINE: If you happen to be behind the wheel right now and you skimped on sleep last night, getting less than the recommended seven hours, AAA has calculated your risk of crashing. Here's AAA's Jake Nelson.

JAKE NELSON: So if you sleep only five to six hours in a given night, your risk of causing a traffic crash has been essentially doubled.

AUBREY: That's a lot - a doubling of the risk. Is that a surprise?

NELSON: Yeah, I don't think that people realize how important sleep is to their ability to safely operate a car.

AUBREY: Nelson says crash rates continue to spike with every hour of lost sleep. So if you got only four or five hours, your risk of crashing quadruples compared to drivers who got a full night's sleep. And this means...

NELSON: You are equally as impaired as driving while legally drunk.

AUBREY: Last year, 35,000 people died in car crashes in the U.S., and AAA estimates that about 1 in 5 fatal accidents involves a drowsy driver. The AAA report is based on crash investigation data from the National Highway Traffic Safety Administration. It draws on interviews with thousands of drivers involved in police-reported crashes and included questions about how much sleep they got preceding the crash.

Karen Roberts is a nurse in Cincinnati who knows the risks all too well. Years ago after an overnight shift, she crashed while driving home.

KAREN ROBERTS: Never in a million years did I ever think it would happen to me.

AUBREY: Roberts says in the miles before the crash, she was feeling woozy, so she jacked up the volume on the Christmas music she had playing to stay awake. She says she almost stopped to get out of the car and buy a caffeinated drink, but...

ROBERTS: I thought, no, I'm on the home stretch. I'll be home within minutes.

AUBREY: Roberts crossed the double line and struck another driver head on. Both cars were totaled. The driver of the other car walked away with a thumb injury, but Roberts' injuries were much worse, and she still has not fully recovered.

ROBERTS: I have been left with double vision. I have chronic excruciating headaches that I experience.

AUBREY: Given the risks, AAA's Jake Nelson says the bottom line is this.

NELSON: If you have not slept seven or more hours in a given 24-hour period, you really shouldn't be behind the wheel of a car.

AUBREY: And this means lots of Americans may want to rethink their sleeping habits. The CDC says 35 percent of adults in the U.S. usually sleep less than seven hours a night. The good news for drivers, Nelson says, is that you don't need to get that sleep all at once. Naps can help.

NELSON: Taking a 10- to 20-minute nap but not to exceed 30 minutes every couple of hours on a long drive has huge safety benefits in terms of your ability to drive without crashing.

AUBREY: Because once you've dozed off behind the wheel, it's too late. Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.