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Drowsy driving is a widespread issue among motorists in the United States. According to the National Highway Traffic Safety Administration (NHTSA), drowsy driving led to roughly 72,000 accidents, 44,000 injuries and 800 deaths in 2013 alone.

This article will explore some of the key warning signs and risk factors associated with drowsy driving, as well as some prevention tips to help you avoid getting behind the wheel when you are sleep-deprived. First, let’s look at the way ‘drowsy driving’ is currently defined and evaluated by both the scientific and law enforcement communities.

What Is Drowsy Driving?

Drowsy driving, also referred to as ‘driver fatigue’, occurs when someone is too tired to operate a motor vehicle and, in turn, puts themselves, their passengers and other motorists in danger. Some of the most common causes of drowsy driving include the following:

  • Inadequate, interrupted or fragmented sleep
  • Chronic insomnia, narcolepsy and other sleep disorders
  • A work schedule that affects amount of sleep and/or circadian rhythm
  • Driving for too long without a sufficient rest period
  • Use of sedatives, hypnotics and other sleep aids prior to driving
  • Consumption of alcohol or narcotics
  • Any combination of these factors

The effects of drowsy driving will vary from person to person. Most fatigued drivers have slower reaction times, and often experience short-term memory loss while behind the wheel. Drowsiness has also been linked to overly aggressive driving.

The following statistics highlight the scope of drowsy driving as a nationwide problem:

  • Roughly 168 million American drivers ? or 60% of the population ? claim to have operated a vehicle while drowsy in the last year. [DrowsyDriving.org]
  • More than one-third of drivers have ‘nodded off’ behind the wheel at least once, and 13% report doing so in the past month. [DrowsyDriving.org]
  • Remaining awake for 18 straight hours can cause impairment that is roughly equivalent to a blood alcohol concentration (BAC) of .05, while being awake for 24 hours can cause impairment similar to a .10 BAC. In most states, a BAC of .08 or higher is considered legally drunk. [DrowsyDriving.org]
  • Between 1999 and 2008, drowsy driving is believed to have played role in 7% of collisions in which a vehicle was towed from the accident scene, 13% of crashes involving at least one hospitalized person and 17% of vehicular fatalities. [AAA Foundation]
  • Between 2005 and 2009, it is estimated that drowsy driving caused roughly 4,400 vehicle collisions and more than 5,000 fatalities. [NHTSA National Center for Statistics and Analysis]

However, it should be noted that these statistics can be somewhat misleading because drowsy driving can be mistaken for other causes, such as distracted driving or driving under the influence of drugs and/or alcohol. As a result, drowsy driving cases often go unreported.

Investigators can use certain clues to pinpoint a high likelihood of drowsy driving at accident scenes. Most accidents involve single cars with serious or fatal injuries, and there are usually no skid marks or other signs that the driver attempted to avoid the collision. And, not surprisingly, most drowsy driving incidents occur between the hours of 12am and 7am ? when we are biologically programmed to be sleepy.

Although many states have enacted or are currently pursuing laws designed to crack down on drowsy driving, there are no blood or breath tests that law enforcement officers can administer to evaluate motorists for this condition. Police may stop a car for general reckless driving, but in general people caught for drowsy driving face less severe penalties than drunk drivers.

Preventing drowsy driving is also difficult at the agency level. Many roads feature rumble strips, or sequences of plastic bumps along the shoulder designed to alert drivers when their vehicle leaves the roadway. Frequently spaced rest areas can also cut down on driver fatigue. Additionally, drowsy driving is a citable driving infraction in most states ? although these are much less severe than penalties for drunk driving. Authorities today stress that the ultimate responsibility for preventing drowsy driving falls on individual drivers.

Who Is at Risk for Drowsy Driving?

Every driver is susceptible to drowsy driving, but this issue is more commonplace with certain groups. Men, for instance, are more likely to be involved in a drowsy driving accident than women; this trend spans all age brackets. Other groups considered at-risk for drowsy driving include the following:

Young Drivers

Drivers between the age of 18 and 29 are considered especially prone to drowsy driving for multiple reasons. For one, younger drivers simply do not get drowsy in the same way as older individuals. This is due to the high-functioning sleep cycle of teenagers and young adults; they are able to resist becoming drowsy more easily, but they are also at risk higher of suddenly falling asleep without warning.

Sleep deprivation is another factor. While most adults require seven to eight hours of nightly sleep, teenagers and young adults need at least nine in order to achieve the same levels of daytime functionality. However, the average young person gets between five and seven hours of sleep on a nightly basis. These one to three lost hours per night can accumulate with each passing day. This buildup is known as sleep debt ? and by the end of a standard five-day week, the average young person has accrued a sleep debt of 10 hours. This puts them at risk for falling asleep while driving, just as the weekend arrives.

Studies have also linked high rates of drowsy driving to the typically early schedules of young people who work or attend school. The Journal of Clinical Sleep Medicine noted a connection between car accidents and students who begin their day before 7am, and a similar study noted that vehicular crash rates involving teen drivers dropped 16.5% after classes shifted to later start times. Additionally, young people are biologically programmed to stay up later, and high school and college students are often required to study past their normal bedtimes. Many jobs popular among teens and people in their 20s include late or shift work schedules, as well.

It is believed that drivers between the age of 18 and 29 account for more than half of all drowsy driving accidents in the United States. The table below looks at the high likelihood of a drowsy driving accident involving young people, compared to other age groups. This data comes from a poll published by the National Sleep Foundation.

Age Group Likelihood of Being Involved in a Drowsy Driving Accident
18 to 29 71%
30 to 64 52%
65 and older 19%

Young people are encouraged to adopt a healthy sleep schedule in order to reduce their risk of drowsy driving. Lifestyle choices are also key. Using tobacco, consuming alcohol or drugs and using electronic devices at night are some of the leading causes of sleep deprivation among young people.

Shift Workers and Commercial Drivers

According to the the Bureau of Labor Statistics (BLS), roughly 15% of the country’s full-time wage and salary workers follow a shift work schedule. Shift work is currently defined as any work schedule that falls outside the standard business day of 9am to 5pm. Shift work may refer to swing shifts, which usually begin in the mid-afternoon and end at midnight or later; and graveyard shifts, which typically span from late evening to early morning. Shift work also includes shifts that cover 20 to 40 consecutive hours; these schedules are commonly found in industries where round-the-clock personnel are needed, such as healthcare, law enforcement and fire protection.

A study by the National Institute for Occupational Safety and Health noted that car crashes account for roughly 22% of all work-related deaths ? and drowsy driving is considered the leading cause for 7% of these fatalities. Drowsy driving has also been noted in particular industries where shift work is common. For example, medical interns with shifts that span 24 hours or longer are more than twice as likely to be involved in a vehicular accident, and five times as likely to experience a ‘near-miss’ incident while driving to or from work.

There are several ways for shift workers to mitigate the risk of drowsy driving. Carpooling and ride-sharing will reduce their time behind the wheel each week. Shift workers are also discouraged from taking lengthy or overtime shifts if they plan on driving themselves to and from work; employees who work more than 60 hours per week are 40% more likely to be involved in a drowsy driving incident.

For more information on the effect that shift work can have on sleep, check out our guide to shift work sleep disorder.

Commercial Drivers

Commercial drivers are considered particularly at-risk for drowsy driving. Many of these employees follow shift work schedules, and their job requires long days ? and often nights ? behind the wheel. Roughly 13% of commercial drivers involved in a large truck collision report being drowsy behind the wheel.

The Federal Motor Carrier Safety Administration (FMCSA) discourages commercial drivers from operating their vehicles between the hours of 12am to 6am, and also 2pm to 4pm; these are periods when we naturally begin to get drowsy. Napping for up to 45 minutes, and then allowing an extra 15 minutes to wake up, can help drivers restore their energy during break periods. They can also increase their alertness by following a proper diet and abstaining from sleep-inducing medications.

The FMCSA also warns of ‘tricks of the trade’ that commercial drivers use to stay awake. These include using tobacco, consuming caffeine, turning up the radio and/or rolling down the window. Although these activities can provide momentary bursts of renewed energy, none of them have much lasting power. This can quickly lead to drowsiness. Rather than relying on these temporary tactics, it’s important for drivers to recognize the warning signs of drowsiness ? and get off the road as soon as they begin to experience these symptoms.

Business Travelers

Business trips involving long journeys can take a toll on your body and affect your circadian rhythm. This is especially true of international travel, since returning home typically involves readjusting to the local time. The transition period ? commonly referred to as jet lag ? may include periods of sleeplessness and/or fatigue. Flights that depart or arrive in the early morning or late night hours can also impact your sleep schedule. For these reasons, pilots, flight crews and other airline personnel are also at risk for drowsy driving after their shifts have ended.

Business travelers are encouraged to commute to and from airports using taxis or car services. For airline employees, a carpooling or ride-sharing schedule may also be feasible. You can also mitigate the effects of jet lag prior to your trip by gradually adjusting to the local time of wherever you’re headed. During long flights, also try to follow a sleep schedule that aligns with the time zone of your destination. Abstaining from alcohol, tobacco and other stimulants like caffeine while in the air can also ease the jet lag process.

People with Sleep Disorders

Many sleep disorders can cause drowsiness. These include the following:

  • Sleep onset insomnia: Difficulty falling asleep during normal sleep periods.
  • Sleep maintenance insomnia: Difficulty staying asleep during normal sleep periods.
  • Obstructive sleep apnea: Temporary loss of breath during sleep that can disrupt the circadian cycle and lead to daytime fatigue.
  • Narcolepsy: The tendency to fall asleep when calm or relaxed, even while being active during the day.

Sleep disorders affect millions of Americans, but they often go undiagnosed. A driver with an undiagnosed sleep disorder is at high risk of being involved in a drowsiness-related accident. Alternatively, many people who are diagnosed with sleep disorders take sleep-inducing medication to help them get enough rest on a daily basis. These medications also increase the likelihood of a drowsy driving incident.

If you live with a sleep disorder or suspect you may have one, it’s important to speak with a physician as soon as possible. People with sleep disorders who must commute long distances are discouraged from taking medications with soporific side effects.

Drowsy Driving Prevention

Now that we have discussed some of the risk factors associated with drowsy driving, let’s look at some preventative measures you can take to reduce your likelihood of being involved in a drowsy driving collision.

  • Get some sleep: This one may seem like a given, but most drowsy driving incidents are the result of a driver who is not fully rested. The best way to decrease drowsiness behind the wheel is to ensure you’ve gotten enough sleep before getting in the car. Learn to recognize the ways that drowsiness and fatigue affect you individually, and avoid driving if you are sleep-deprived.
  • Bring a friend: A recent UCLA study found that 82% of drowsy driving incidents were caused by single-occupant vehicles. Passengers can greatly decrease your chances of falling asleep while driving. Furthermore, a licensed passenger may be able to take over in the driver’s seat if you become sleepy behind the wheel.
  • Use rest stops: Commonly found along our nation’s freeways and highways, rest areas are designed as safe spaces where you can park your car and, if need be, take a quick nap. Some rest stops will only allow you to remain in the area for up to an hour, but this should be adequate time for a restful nap. A popular trend among today’s drivers is to take a caffeine nap, or consume a caffeinated beverage and then get some shuteye. The caffeine will take effect after 15 to 20 minutes, leaving the napper feeling even more refreshed when they wake up. Speaking of caffeine…
  • Manage your caffeine intake: In addition to coffee, caffeine can also be found in a wide range of teas and carbonated beverages. Chocolate is another good source. While caffeine will provide extra energy, it is not an adequate replacement for sleep. So if you feel yourself getting drowsy after a cup of joe and a candy bar, then you should consider stopping for a nap.
  • Chew gum: Chewing gum exercises your jaw muscles, which can stimulate your senses and increase alertness. This is a good temporary energy source if you are not hungry or thirsty.
  • Get plenty of fresh air: Carbon dioxide can make us feel sleepy, especially in stuffy car interiors. Opening car windows or adjusting the vent controls to bring in outside air can lower carbon dioxide levels and, in turn, reduce the risk of drowsy driving.
  • Listen to music: The solo driver’s best friend is often the radio. Rather than listening to at a high volume ? which can damage your hearing ? consider listening to energetic music.
  • If possible, drive while the sun shines: Your circadian rhythm will keep you feeling more awake and alert during the daylight hours. Additionally, sunlight stimulates your brain and extends your reaction time while driving. Natural sunlight is also a source of Vitamin D, which can help you sleep better at night.
  • Use an app: Car manufacturers are currently developing automated systems to help drivers avoid drowsiness. In the meantime, a smartphone app can provide the same service. One of the most popular options is Drowsy Driver, an android app that monitors driver eye activities when the smart device is mounted on the dashboard.
  • When in doubt, check into a room: If you feel drowsy and there don’t appear to be any rest areas nearby, then you should consider checking into a hotel, motel or other roadside lodging facility. Ask at the front desk if they offer an hourly room rate; this may allow you to catch a few hours of sleep and be back on the road relatively soon.

Remember: it is dangerous and against the law to pull your car onto the shoulder of a freeway or highway in order to sleep.

Alcohol use is another important consideration. The effects of alcohol on humans vary from person to person, and often depend on factors like weight and medical history. The general rule of thumb is that 12 ounces of beer, five ounces of wine and 1.5 ounces of liquor are all roughly equivalent ? and that more than three individual servings of any combination over the course of a few hours will cause intoxication. However, even one serving of alcohol can cause you to become drowsy.

Additionally, it’s important for people who regularly take medication to read the warning labels ? even if they have been prescribed for a non-sleep-related condition. The following medication types are designed to induce drowsiness to some extent:

  • Hypnotics and other sleep aids
  • Narcotic pain relief pills
  • Antidepressants
  • Tranquilizers
  • Certain medications for high blood pressure
  • Cold medicine
  • Certain antihistamines
  • Muscle relaxants

Finally, understanding your own individual symptoms of drowsy driving is critical when you are on the road. If you are concerned about your fatigue level and worried that drowsiness may be impacting your driving, here are a few considerations to make:

  1. Are you yawning or blinking frequently? Is your head suddenly feeling really heavy? These are some of the ways your body will let you know you’re tired.
  2. If you are driving on familiar roads, have you missed any traffic signals? As you become more tired, your mind often focuses on controlling the car ? and as a result, you may drive right through a traffic signal or stop sign.
  3. How close are you to the vehicle in front of you? Drowsy drivers often (and unintentionally) tailgate other vehicles.
  4. What do you remember about the last few miles of your drive? As your body gets more exhausted, you will likely remember fewer details of the drive.
  5. Are your thoughts coherent? Or is your mind wandering all over the place? Pay attention to your mental activities, and pull over if you have a hard time thinking clearly.
  6. Did you miss your exit? Are you aware of your current location in relation to other exits?
  7. Are you starting to lose control of the car? Has your vehicle started swerving? Have you been jarred awake after inadvertently crossing the rumble strip?

If you answered yes to any of these questions, then you should get off the road immediately and refrain from driving until you are properly rested.

Driver Resources

No matter how roads are engineered to cut down on driver fatigue or vehicles are programmed to provide drowsiness alerts, the responsibility for safe and vigilant driving will always fall on the driver. By following the guidelines laid out in this article, you can make the road safer for you, your passengers and other drivers.

For more information about drowsy driving identification and prevention, check out the following online resources:

General Information

  • DrowsyDriving.org: This comprehensive site maintained by the National Sleep Foundation includes facts and statistics about drowsy driving, warning signs and preventative measures, as well as links to books and media on the subject.
  • Federal Motor Carrier Safety Administration: The FMCSA offers a few anti-fatigue tips for commercial motor vehicle drivers. The organization also offers a self-questionnaire about drowsy driving designed for commercial drivers to take before hopping in the driver’s seat.
  • Centers for Disease Control: The CDC features a page dedicated to ‘Drowsy Driving: Asleep Behind the Wheel’. This information includes stats, prevention methods and links to several government reports and academic journal articles about drowsy driving.
  • UCLA Sleep Disorders Center: UCLA’s comprehensive guide covers some of the facts ? and myths ? about the causes and effects of drowsy driving. This information is provided in English and Spanish.
  • AAA Foundation for Traffic Safety: AAA’s online guide to drowsy driving includes general facts, statistics and a news ticker for breaking stories related to this topic.
  • Drowsy Driver: This smartphone app is designed to help drivers cut down on drowsiness behind the wheel. Operating the app is simple: attach your smart device to the dashboard of your vehicle, and the app with scan your eyes and monitor blinking cycles in order to detect drowsy patterns. This app is currently free, and exclusively available for Android devices.

Resources for Teen Drivers

  • Teens in the Driver Seat: Designed as a ‘peer-to-peer safety program for America’s youth’, Teens in the Drivers Seat offers a wide range of resources for drivers under the age of 20. The site’s drowsy driving guide features statistics, prevention strategies and a couple of helpful videos.
  • Prom Night Spoiler Alert: Published by the American Academy of Dental Sleep Medicine, this online pamphlet highlights the dangers of drowsy driving ? and offers advice for teens who plan to get behind the wheel after dark.
  • National Sleep Foundation: The NSF released this drowsy driving guide for young people to coincide with Drowsy Driving Prevention Week, which is observed every November. The publication lists a few notable do’s and don’ts for teen drivers, such as ‘do drive with a friend’ and ‘don’t drive at times when you would normally be sleeping’.
  • New York State Department of Health: This guide is aimed at both teen drivers and their parents who fear their child might be at risk of drowsy driving. Structured in an FAQ format, the article answers questions like ‘what are the warning signs?’ and ‘should my child use caffeine and energy drinks to stay alert?’
  • Journal of Clinical Sleep Medicine: Published in 2008, this academic study draws a direct link between teenage sleep patterns, school start times and the incidence rate of drowsy driving incidents.