We all know that we ought to get the seven to nine hours of recommended sleep every night, but actually sticking to that schedule can sometimes be tough. However, a new study from the AAA Foundation for Traffic Safety may serve as a grim reminder that a lack of sleep may be extremely dangerous, especially when it comes to operating a vehicle.

When AAA’s not-for-profit research and education organization recently took a look at sleep deprivation and traffic accidents, it found that your risk of a crash nearly doubles with just one hour less of sleep than usual. Around 82% of Americans recognize that an extra hour of shut-eye can be valuable, but just how valuable, according to the study, is rather shocking.

Drivers who got only five or six hours of sleep during the previous 24 hours were involved in 1.9 times as many accidents as drivers who routinely had seven or more. Those who got only four to five hours of sleep were 4.3 times as likely to be involved in traffic accidents. And those who got less than four or five hours of sleep per night were 11.5 times more likely to be involved in an accident, rates not too dissimilar from drivers with blood alcohol content levels over the legal limit of 0.08.

“Our new research shows that a driver who has slept for less than five hours has a crash risk comparable to someone driving drunk,” said David Yang, executive director for the AAA Foundation. “You cannot miss sleep and still expect to be able to safely function behind the wheel.”

The findings were based on an analysis of 7,234 drivers involved in 4,571 crashes using federal data. But it only included daytime accidents, and none that happened between the hours of 12 midnight and 6 a.m., when drowsy driving might be even more dangerous.

A full 97% of drivers surveyed said that they believed driving on a lack of sleep was unacceptable behavior, yet one in three admitted to doing it in the past month. Furthermore, more than half of drivers involved in fatigue-related crashes experienced no warning symptoms — drooping eyelids, drifting between lanes, etc. — before their accidents happened. That means that adequate sleep itself should be a top priority for preventing road mishaps.

“Managing a healthy work-life balance can be difficult and far too often we sacrifice our sleep as a result,” said Jake Nelson, director of traffic safety advocacy and research for AAA. Failure to do so, he added, “could mean putting yourself or others on the road at risk.”