When you get behind the wheel of a car without proper sleep, you put yourself and everyone else on the road at risk. In fact, the AAA Foundation for Traffic Safety says that people who sleep 6-7 hours a night are twice as likely to be involved in a crash than are people who sleep 8 hours a night.
That doesn't stop many of us from driving drowsy, though. In a 2005 National Sleep Foundation poll, 37 percent of people said they had fallen asleep at the wheel, and 13 percent said they did so once a month. Nearly a quarter of adults say they know someone personally who has crashed due to falling asleep while driving. The National Highway Traffic Safety Administration estimates 100,000 (this is likely to be a conservative number) police-reported crashes are the direct result of sleepy drivers every year, resulting in a roughly 1,550 deaths and 71,000 injuries.
Some of us are more likely than others to be on the road when we're tired. Young adults ages 18-29 are more likely to say they've driven drowsy (71 percent), compared to roughly half of adults ages 30-64. Indeed, it's estimated that younger drivers account for almost two-thirds of drowsy-driving crashes, even though they represent only one fourth of licensed drivers.
Men are more likely to drive drowsy than women (56 vs. 45 percent) and are almost twice as likely to fall asleep at the wheel. With their irregular schedules, it's not surprising that shift workers often drive drowsy to and from work. And unfortunately, adults with kids are also more likely than childless adults to be sleepy behind the wheel.
We all know that alcohol impairs our driving skills, but alcohol and sleep-deprivation together are especially dangerous. Sleepiness exacerbates the sedating effects of alcohol, and the combination of the two affects a person's ability to move and think clearly—more so than either of the two alone. Researchers have seen that when people are sleepy, alcohol has a greater effect on their driving ability. For example, using an in-laboratory driving simulation, one study found that even with alcohol levels within the legal limit, drivers with eight hours of sleep deviated from the road four times more than sober drivers, but those with four hours of sleep veered off the road 15 times more. Another study found that more than a third of drivers involved in drowsy-driving crashes had consumed some amount of alcohol. In fact, driving without sleep for just one night produces sedating effects equal to 10 alcoholic beverages. Ask yourself: "Would I want to be on the road with anyone following a night of sleep loss?".