Missing sleep can make you grouchy the next day, but a new study by the AAA Foundation for Traffic Safety reveals another negative impact.
According to the report, drivers who get fewer than seven hours of sleep can expect their crash risk to jump significantly, as much as 11 times normal.
Nearly all drivers surveyed (97 percent) viewed drowsy driving as dangerous and unacceptable, yet nearly one in three admitted they'd driven while drowsy at least once in the past month. This tracks with numbers from the Centers for Disease Control and Prevention, which reports that 35 percent of U.S. drivers sleep less than the recommended seven hours daily.
Drowsy driving winds up being a factor in more than one in five fatal crashes on U.S. roadways each year.
Based on an analysis of 7,234 drivers who had been involved in 4,571 crashes, the study found that the crash risk increases steadily as drivers shorten the amount of sleep they below the seven-hour benchmark.
Getting six to seven hours of sleep leads to a 30 percent increase in risk. Drivers that sleep five to six hours can expect a 90 percent risk increase. Sleeping for only four to five hours increases the crash risk by 330 percent.
For the biggest risk of a crash, get less than four hours of sleep. That level of drowsiness leads to a whopping 1,050 percent increase in crash risk.
"You cannot miss sleep and still expect to be able to safely function behind the wheel," says David Yang, executive director for the AAA Foundation. "Our new research shows that a driver who has slept for less than five hours has a crash risk comparable to someone driving drunk."
AAA recommends that drivers travel at times when they're normally awake, and not start early or stay up late. To keep alert during a trip, schedule rest breaks every two hours or 100 miles.
Avoid heavy foods while on the road, and travel with a passenger who can take turns driving. Drivers should also keep away from any medications that might cause drowsiness.