When lack of sleep can kill
You're driving down a highway on a pleasant afternoon. Traffic is light and the road is straight and your eyelids begin to droop. You yawn and open the window. You shift in your seat. You slap your cheek. Suddenly you are heading for an embankment at 60 mph with your eyes closed.
That scenario is frighteningly common in a nation that burns the candle at both ends. Some 60 percent of Americans say they have driven while drowsy, and 37 percent admit to nodding off at the wheel, according to the National Sleep Foundation.
Lack of sleep is a factor in one-fifth of motor-vehicle accidents and near accidents, studies conducted for the National Highway Traffic Safety Administration found. It's also to blame in one-third of fatal truck accidents -- equivalent to alcohol and drugs combined.
Even those numbers underestimate the problem, experts say. Unlike alcohol, sleep leaves no markers in a driver's blood or breath. But there are telltale signs: Cars with a sleeping driver often drift out of their lane until they hit something and show no sign of braking.
"Some people drift to the center. I drifted to the right," says Tom Callaghy, a professor at the University of Pennsylvania who was driving in Virginia in 2001. He knew he was sleepy and leaned over to wake his wife but nodded off momentarily and plummeted down a gulley. A tree slammed through the passenger side, killing her instantly.
Even without actually falling asleep, drivers can go for miles in what some experts call "highway hypnosis," with their reflexes slowed and their judgment impaired. And it doesn't take much to reach that state. Averaging four hours of sleep for five nights builds the same level of cognitive impairment as being awake for 24 hours -- the equivalent of legal drunkenness, says Charles Czeisler, a professor of sleep medicine at Harvard Medical School. Having one beer in that condition, he notes, has the impact of a six pack.
Chronic sleep deprivation has also been linked to diabetes, heart attack, stroke, high blood pressure, depression and obesity, which leads to obstructive sleep apnea, which causes even more sleep deprivation, according to the Institute of Medicine.
Yet Americans think nothing of working long hours and then getting on the road. "Our society thinks sleep is for slackers," says Darrel Drobnich, acting CEO of the National Sleep Foundation.
More than half of sleep-related crashes are caused by drivers under 25. Teens need more sleep than adults, due to brain and hormonal changes, but they often get much less, between homework, activities and delayed sleep rhythms, and schools days that start early. And while drunk driving is associated with bad kids, Drobnich says, it's often high achievers who are vulnerable to sleep-related accidents.
Some states restrict young drivers to daylight hours to reduce the risks. Laws to specifically outlaw driving on little sleep are pending in several states; now, New Jersey has the only one. Some auto makers are testing technologies that alert drivers if their eye movements suggest drowsiness or if a car seems out of control.
But nothing substitutes for sleep, experts say. "If your eyes are getting heavy, you should have been off the road a half-hour ago," says Drobnich. Opening the window or turning on the radio have very limited effect, studies have shown. Often, the more you fight the urge to sleep, the stronger it becomes. "The body's homeostatic drive for sleep can seize control involuntarily," says Dr. Czeisler.
Caffeine can temporarily block the sleep receptors in the brain. But pulling over for a 20-minute nap is more effective, experts say. Better yet, plan ahead to get at least seven hours of sleep the night before you drive. Take breaks and have another adult with you, awake, who can spell you. And if you're unavoidably tired, ask yourself if this trip is worth the risk.
"Drive responsibly. Don't think you're just going to get through it," says Callaghy. "You really never know how sleepy you are."
Too tired to drive?
You should pull over if you are:
• Blinking frequently
• Bobbing your head
• Drifting from your lane
• Missing exits or traffic signs
• Unable to remember the last miles driven