The more sleep drivers miss, the higher their risk of being in a crash, researchers find

Washington — Drivers who don’t get the recommended minimum of seven hours of sleep a night are at higher risk of being involved in a motor vehicle crash – and that risk increases among drivers who get the least amount of sleep, according to new research from the AAA Foundation for Traffic Safety.

Researchers analyzed data from previous Department of Transportation research that involved in-depth investigations of 5,470 crashes, including interviews with the drivers.

Results showed that the more sleep drivers missed, the more likely they were to make a miscalculation behind the wheel.

“We found that drivers who missed an hour or two of sleep relative to the expert-recommended minimum of seven hours generally made a lot of the same mistakes that well-rested drivers make, like not doing a good enough job of checking traffic before entering an intersection, misjudging another vehicle’s speed or allowing themselves to become distracted,” study co-author Brian Tefft told Safety+Health. “The difference was that the drivers who didn’t get enough sleep made these mistakes more often.”

Tefft said drivers who missed more than two hours of sleep also were much more likely to fall asleep at the wheel.

Drivers who had slept less than four hours in the previous 24 hours had the greatest risk of being involved in a crash. Nearly one-third of the drivers studied who were operating on less than four hours of sleep over the previous 24 hours fell asleep at the wheel, while another third made errors such as overcorrecting or driving off the road, Tefft said.

According to the researchers, those drivers had a comparable crash risk to those who drive with a blood-alcohol concentration of 1.5 times the legal limit.

For drivers who know they are sleep-deprived, Tefft suggests they get more sleep – “even just a quick nap” – before getting on the road.

“If you find yourself struggling to keep your eyes open or not remembering the last few miles that you drove,” Tefft said, “these are warning signs that you should find a safe place to pull over and take a quick power nap before you continue on your way.”

AAA recommends that drivers travel during times they normally are awake, avoid heavy foods, and do not take medications that cause drowsiness or impairment. For longer trips, drivers should schedule a break every two hours or 100 miles, and travel with an alert passenger who can take turns driving.

The study was published Oct. 1 in the journal SLEEP.