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Drowsy Driving

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“Drowsy driving” occurs when a person who is operating a motor vehicle is too tired to remain alert. As a result the driver may have slow reaction times, reduced vigilance and impaired thinking. In the worst case the driver may fall asleep behind the wheel.

The U. S. National Highway Traffic Safety Administration (NHTSA) reports that drowsy driving is related to at least 100,000 motor-vehicle crashes and more than 1,500 deaths per year. About 71,000 drowsy-related crashes involve non-fatal injuries.  The estimated annual monetary loss related to drowsy driving is about $12.5 billion.
Drowsy-Driving Accidents
In a recent study the NHTSA and the Virginia Tech Transportation Institute installed instruments and sensors in 100 vehicles. These vehicles were driven for everyday use by ordinary drivers for one year. Results show that drowsiness was the most common driver impairment. Drowsy driving was involved in 14 percent of crashes and 11 percent of near-crashes. By comparison, impairment due to drugs and alcohol was involved in only 2 percent of crashes and no near-crashes.
Drowsy driving often goes unreported when police complete an accident report. Unless the driver admits falling asleep, drowsy driving can be difficult to detect. But many drowsy-driving accidents share some common features. These include:
  • Time
Accidents are most common late at night and early in the morning. This is the body’s natural sleep period.   Sleepiness also can peak in the middle of the afternoon. Older adults are more likely to have a drowsy-driving accident in the mid-afternoon.
  • Speed
Accidents often occur at high speeds on highways and other major roadways.
  • Vehicle
Accidents often involve one vehicle that veers off the road. A study by the NHTSA and the Virginia Tech Transportation Institute found that drowsy driving was related to 20 percent of all single-vehicle crashes and 23 percent of near-crashes.
  • Avoidance
The driver often makes no attempt to apply the brakes or avoid the crash.
  • Severity
Accidents often result in injury or a fatality.
Drowsy Drivers
Drowsy driving is common. In 2002 the NHTSA sponsored a Gallup survey of more than 4,000 people. Thirty-seven percent of people reported falling asleep or nodding off at least once while driving. Ten percent of drowsy drivers had driven drowsy in the past month. This represents about 4 percent of the driving population or an estimated 7.5 million drivers who have driven drowsy in the past month.   
Even one night of sleep loss or poor sleep can put you at risk of drowsy driving. But certain people have a higher risk of drowsy driving than others. These people include:
  • Young Men
Drowsy-driving accidents are most common among young men in their teens, 20s and 30s. These accidents tend to occur between 11 p.m. and 8 a.m.
People who work night shifts or rotating shifts are at risk for drowsy driving. This includes people who work as doctors, nurses, truck drivers, pilots and police officers. The risk of drowsy driving is great when they drive home after work.
A 2007 study in the journal Sleep shows how common this problem can be. The four-week study involved 895 full-time hospital nurses. Almost 600 of the nurses reported at least one episode of drowsy driving during the study. Thirty nurses reported struggling with drowsy driving after every shift.
  • People with Untreated Sleep Disorders
Many people with either obstructive sleep apnea or narcolepsy remain untreated. A common side effect of sleep apnea is severe daytime sleepiness. Narcolepsy can cause you to fall asleep suddenly. These sleep disorders put you at risk for drowsy driving.
  • People Taking Medications
Many medications cause sleepiness as a side effect. People taking these medications are at risk for drowsy driving.
Drowsy-Driving Warning Signs

These are some of the warning signs of drowsy driving:

  • You keep yawning.
  • You are unable to keep your eyes open.
  • You catch yourself “nodding off” and have trouble keeping your head up.
  • You can’t remember driving the last few miles.
  • You end up too close to cars in front of you.
  • You miss road signs or drive past your turn.
  • You drift into the other lane of traffic.
  • You drift onto the “rumble strip” or onto the shoulder of the road.

Drowsy-Driving Prevention

Rolling down the windows or turning up the volume on the radio will do little to increase your alertness while driving. These are some better ways to avoid drowsy driving:
  • Get a full night of seven to eight hours of sleep before driving.
  • Avoid driving late at night.
  • Avoid driving alone.
  • On a long trip, share the driving with another passenger.
  • Pull over at a rest stop and take a nap. 
  • Use caffeine for a short-term boost.
  • Take a short nap after consuming caffeine to maximize the effect.
  • Arrange for someone to give you a ride home after working a late shift.

Updated August 5, 2008

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