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The Dangers of Drowsy Driving

Sleep drivers are dangerous drivers!

As the investigation into New York’s Metro-North train derailment continues, attention has focused on the alertness of the train’s driver. Reports indicate that the engineer at the controls dozed off, and that an alert system designed to activate automatic brakes when a driver is incapacitated was not present in the cab. One source involved in the investigation described the train engineer’s condition before the derailment as “almost hypnotized,” in a trance-like state between sleep and waking.

This investigation raises some important questions—not only about transportation workers and their sleep habits, but also about drowsy driving in general. How many of us can relate to that feeling of in-between sleep and wakefulness while behind the wheel of our own vehicles? Too many.

New data from AAA Foundation for Traffic Safety indicates that a significant number of us are driving when experiencing excessive and dangerous fatigue. According to a report released by AAA in November, 28% of drivers surveyed said they’d struggled to keep their eyes open while behind the wheel at least once in the past month. Among young drivers, the tendency to drive while drowsy is even higher: 33% of drivers ages 19-24 admitted to struggling to stay awake while driving in the last 30 days.

Drowsy driving doesn’t receive nearly the attention it deserves—in part, perhaps, because it often goes unreported and can be more difficult to pinpoint as a cause or a factor in accidents, compared to other factors such as drugs, alcohol or speeding. But make no mistake: sleepy drivers are dangerous drivers. The National Highway Transportation Safety Administration estimates that drowsy driving contributes to more than 100,000 accidents per year—and that’s a figure that the NHTSA itself believes is low, because of under-reporting of fatigue as a factor in vehicle accidents. Other estimates are significantly higher, reaching as many as 1 million crashes a year resulting from sleepy driving. Research conducted by AAA attributes sleepiness behind the wheel as a cause of 17% of road fatalities in the United States.

As a society we’ve come to vehement consensus that drunk driving is unacceptable behavior. Yet we continue to tolerate sleepy driving. Many people who wouldn’t dream of driving after one drink too many may very well get behind the wheel when feeling drowsy.

One problem that contributes to this dangerous tolerance of drowsy driving? We’re generally not at all good at accurately gauging our own sleepiness, tending to overestimate our ability to focus and underestimate levels of fatigue. What’s more, the environment of driving, especially at night, can bring about drowsiness unexpectedly if you’re not prepared: the repetitive sounds and sights of the road, as well as the rhythm of the moving vehicle, can lull you into dangerously sleepy territory very quickly. The initial phase of sleep, Stage 1, is actually a transitional period between sleep and waking. You can be in Stage 1 sleep and feel as though you’ve been awake. But during this phase, brain waves are slowing, and the body is relaxing in preparation for deeper sleep.

Head-nodding drowsiness is a clear and unambiguous sign that you’re in danger of falling asleep and shouldn’t be driving. But the effects of sleep deprivation can be present—and can compromise safe driving—even if you’re not struggling to keep your eyes open. Being sleep deprived diminishes motor skill performance and slows reaction times, especially for monotonous tasks. Being short on sleep inhibits alertness and vigilance, as well as other more complicated cognitive functions, including decision-making and judgment. There is significant evidence that moderate sleep deprivation—as little as a single night—can lead to cognitive and motor skill impairments that are on par with legal levels of alcohol intoxication.

A single night of lost sleep produces levels of sleep deprivation that make it dangerous to drive. This kind of acute sleep deprivation may be less common for many of us than an ongoing pattern of not sleeping long enough or well enough on a regular basis. This kind of sleep deprivation is also dangerous to driving. Chronic sleep deprivation, the kind often experienced by people with sleep disorders such as insomnia or obstructive sleep apnea, increases risk for drowsy driving. People with obstructive sleep apnea are at significantly higher risk for driving accidents than the general public, according to research. The use of prescription sleep medication—an all-too-common sleep strategy for many Americans—is also associated with increased risk of driving accidents.

The best strategy to avoid drowsy driving is to get plenty of sleep on a regular basis. Take care of your sleep on a daily basis, and talk with your doctor about any problems you’re having with the quantity and quality of your nightly rest. That said, there are other things you can do to improve the safety of your driving, and avoid drowsiness behind the wheel:

  • Leave plenty of time to reach your destination. Make sure to build time in your schedule to take breaks to get fresh air, stretch your legs, and break up the monotony of driving that can itself be fatiguing. If need be, break up extended driving trips with overnight stays, to maintain your regular sleep routine.
  • Avoid late night and early morning driving. A good rule of thumb is to limit driving to times when you wouldn’t be sleeping.
  • Share driving responsibilities. Split driving duties with another driver, and take turns resting when you’re not driving.
  • Don’t rely on caffeine as substitute for sleep. Caffeine may provide a short-term boost to alertness, but the other effects of sleep deprivation can continue to interfere with safe driving.
  • If you’re sleepy, call a friend to assist with the driving! You’d call somebody if you’d had a little too much to drink. Follow the same good, responsible advice for when you’re tired—even if the drive is a short one.

Especially during holiday season, when travel and social activities get people out on roads more often—and often at night—it’s so important to drive responsibly. That includes driving while well rested. Get your rest, don’t drive when you’re tired, and help make this a safe holiday for you and those with whom you share the roads.

Sweet Dreams,

Michael J. Breus, PhD

The Sleep Doctor™

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