How many traffic crashes does drowsy driving cause?

We all know that driving while you’re low on sleep can be dangerous. Some estimates indicate that missing out on just a few hours of sleep can affect your driving in a profoundly negative way. Two to three hours less sleep can quadruple the risk you’ll be in a crash — and that’s equivalent to driving drunk.

Yet federal statistics have long implied that drowsy driving is only responsible for about one or two percent of fatal accidents. Drowsiness is notoriously hard to detect after a crash, however, so the incidence of such accidents may be underreported.

The AAA Foundation for Traffic Safety decided to find out. It put together a naturalistic driving study which could collect evidence of drowsy driving as it occurred.

In a naturalistic driving study, cameras and sensors are installed in the vehicles of ordinary volunteer drivers. In this case, dashboard cameras were installed facing the driver. Using a scientific measure that links the percentage of time a driver’s eyes are closed to the person’s level of drowsiness, researchers reviewed the videos of drivers who had been in crashes. There were over 700 crashes for the researchers to review.

The result? Drowsiness was noted before about 9.5 percent of all the crashes. Moreover, it was recorded in 10.8 percent of the crashes that involved significant property damage.

That means drowsy driving was responsible for nearly eight times more traffic accidents than previous federal estimates showed.

“Drivers who don’t get enough sleep are putting everyone on the road at risk,” said a spokesperson for the foundation. By conducting an in-depth analysis using video of everyday drivers, we can now better assess if a driver was fatigued in the moments leading up to a crash.”

Almost a third of U.S. drivers admit drowsy driving

In a related survey, the AAA Foundation found that 96 percent of U.S. drivers agree that drowsy driving is unacceptable and a serious threat to their safety. Nevertheless, 29 percent said they had driven that way in the last month — so tired they had difficulty keeping their eyes open.

The Centers for Disease Control and Prevention recommends at least seven hours of sleep each night, and AAA urges people not to rely on their bodies’ warning signals to tell them they’re too sleepy.

“Don’t be fooled, the only antidote for drowsiness is sleep,” said a spokesperson. “Short term tactics like drinking coffee, singing, rolling down the window will not work. Your body’s need for sleep will eventually override your brain’s attempts to stay awake.”

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