The public is well educated about the dangers of driving while impaired by medication, alcohol or illegal drugs. But drivers may not be aware that driving while tired can be just as dangerous.
Driving when tired can be a fatal mistake. Just as alcohol or drugs can slow down reaction time, impair judgment and increase the risk of accident, so, too, can being tired behind the wheel. Drowsy driving is reportedly what caused the fatal crash in June 2014 between a limousine and a Walmart truck that ended the life of comic James McNair and seriously injured fellow comedian Tracy Morgan. The driver, Kevin Roper, was going 20 miles over the speed limit and was almost at his drive time limit, according to preliminary reports by the National Transportation Safety Board.
According to the U.S. National Highway Traffic Safety Administration, about 100,000 car crashes in the United States each year occur as the result of an overly tired driver. Various studies demonstrate that drivers who have remained awake for 18 hours prior to driving mimic the driving performance of intoxicated motorists. In fact, drowsy driving can be confused with driving with a high blood alcohol content.
Sleepiness can arise relatively quickly, and according to Thomas Balkin, PhD, director of the behavioral biology program at the Walter Reed Army Institute of Research and a leading expert on sleep and fatigue, it's difficult for drivers to assess just how sleepy they are.
"Sleepiness affects the part of the brain responsible for judgment and self-awareness," he says. "When you've reached the stage where you are fighting sleep, the effect of any method of reviving yourself can be very short-lived."
Furthermore, people do not have to be in a deep sleep to actually be asleep behind the wheel. Micro-sleeps occur when certain brain cells temporarily shut down for a few seconds. A person is not completely asleep but in a sort of fog as if they are asleep.
When sleepiness sets in, the best course of action is to pull off the road. Opening the window, turning on the radio or blasting cold air is, at best, only a temporary solution. If driving with passengers and feelings of sleepiness appear, hand the keys over to a passenger and have them take over driving, if possible. Otherwise, a short nap and a cup of coffee can be used in combination to increase alertness.
It's also a good idea to avoid beginning a long road trip in mid-afternoon around the hours of two or three o'clock. While alertness generally dips in the evening hours, due to the circadian rhythm, alertness also dips in the late afternoon, prompting drowsiness. A 2010 study by the American Automobile Association Foundation for Traffic Safety found that as many drivers reported falling asleep at the wheel in the afternoon hours as reported falling asleep late at night. Driving in a warm, quiet car also may spur drowsiness, as would driving after a heavy meal.
Driving tired is just as dangerous as other impaired driving. Slow reaction times and unawareness of surroundings can contribute to accidents that are otherwise avoidable.