Driving while drowsy is a serious public health problem. At least 100,000 car and truck accidents each year in the U.S. are caused by sleepy drivers. The crashes result in 75,000 injuries and 1,500 deaths. The related monetary loss is estimated to be $12.5 billion per year.

Why sleep-related crashes are more severe

When a driver falls asleep at the wheel, the accident is usually more severe than a fender-bender. This is because in general:

• The accident happens on a high-speed road at 55 mph or above.
• The driver does not attempt to avoid crashing. The driver simply falls asleep and does not brake or steer.
• The vehicle wanders into an oncoming lane or leaves the road completely.

Factors that cause drowsy driving

Sleep disorders are one of the key factors that can increase the risk of sleep-related vehicle crashes. This is why it is so important to seek treatment if you suspect you or a loved one has a sleep disorder such as sleep apnea or narcolepsy.

Here is the complete list of factors that increase the risk of drowsy driving and related accidents. These factors have cumulative effects, so that a combination of them substantially increases crash risk.

• Sleep loss (not getting enough sleep).

• Untreated or unrecognized sleep disorders, especially sleep apnea and narcolepsy.
• Driving patterns, including
  4Driving between midnight and 6 a.m.
  4Driving in the midafternoon hours (especially for
     older persons).
  4Driving a substantial number of miles each year
     and/or a substantial number of hours each day.
  4Driving for longer times without taking a break.
• Use of sedating medications, especially prescribed anxiolytic hypnotics, tricyclic antidepressants, and some antihistamines.
• Consumption of alcohol, which interacts with and adds to drowsiness.

Who is at risk of drowsy driving

There are three groups who are especially at risk of causing vehicle accidents due to drowsiness:

• Young people (ages 16 to 29), especially males
• People with untreated sleep disorders such as sleep apnea and narcolepsy
• Shift workers whose sleep is disrupted by working at night or working long or irregular hours

Sleep disorders can cause drowsy driving. If you or a loved one may have sleep apnea, narcolepsy or other serious sleep disorders, you should seek treatment. It could save a life.

This page also discusses other factors and solutions related to sleepiness and vehicle crashes.

Before you hit the road

Before you get behind the wheel, here are ways to help avoid becoming drowsy while driving:

• Plan to get sufficient sleep
• Do not drink even small amounts of alcohol when sleepy
• Limit driving between midnight and 6 a.m.
• Seek treatment for any actual or suspected sleep disorder such as sleep apnea and narcolepsy

If you begin to nod off while on the road

If you are driving, and start to feel sleepy, it is very important to take preventive action:

• Switch drivers. Let a more alert passenger take over.
• Stop and sleep. On long-distance trips, quit driving for the night and get a motel room. If this is not possible, stop as soon as possible in a safe area, and take a short nap of at least 15 to 20 minutes.
• Consume around 200 mg of caffeine in one of the following forms:
  4One 200 mg caffeine pill (NoDoz, Vivarin)
  4Two 8 fl. oz. cups of regular (caffeinated) coffee
  4Five 8 fl. oz. cups of black tea
  4Ten 8 fl. oz. cups of green tea
  4Three 12 fl. oz. cans of energy drinks (Red Bull, Jolt)
  4Five 12 fl. oz. cans of caffeinated soda (Pepsi, Coke)

The effectiveness of any other steps to improve alertness when sleepy, such as opening a window or listening to the radio, has not been demonstrated.

Sources and additional information

The information cited above is adapted from a report by the National Center on Sleep Disorders Research (NCSDR) and the National Highway Traffic Safety Administration (NHTSA) Expert Panel on Driver Fatigue and Sleepiness. The report, entitled "Drowsy Driving and Automobile Crashes," is available from the NHTSA and also in a slightly different format from Accident Reconstruction Newsletter. Many of the caffeine equivalents are from the Wikipedia article on caffeine.

A good, easy-to-read overview is "Driving While Drowsy," an article by Jack Nerad which is available at DrivingToday.com.

The National Sleep Foundation maintains a section of their website called DrowsyDriving.org. It contains statistics, policy information, prevention resources, and even recent news about sleep-related accidents.

NOTE: Sleep health information discussed at this website is for educational purposes. Each
            individual is different and may have varying symptoms, diagnosis and treatments.
            If you are having sleep health problems, obtain professional medical advice.

©2006, Morris T. Bird, M.D. and Robert S. Thornton, M.D.
Medical Directors of the Center for Sleep Disorders at Florida Hospital
Solving sleep problems, snoring, sleep apnea, insomnia and other sleeping issues in Central Florida.
With six sleep centers at Florida Hospital locations:
   Orlando Main Campus, East Orlando, Altamonte Springs, Celebration, Winter Park and Apopka