Drowsy Driving Sleep Risks

Drowsy Driving: The Danger, the Causes, and Prevention

For years, drivers have been educated about the risks of driving under the influence. More recently, public service announcements have warned of the dangers of driving while texting. But there is another danger out there that many people may not consider. Driving while drowsy is a big problem and it may be on the rise.

Although it might not be something most people think about, it’s not surprising that drowsy driving is on the rise. According to the CDC, about one-third of adults in the United States report sleeping less than seven hours a night. Since most people need between seven and nine hours of sleep, a significant portion of the population probably has some degree of sleep deprivation. That lack of sleep can affect driver safety.

According to the AAA Foundation for Traffic Safety, it is estimated that 21 percent of fatal crashes that occurred in 2014 were due to drowsy drivers. A previous study conducted in 2010 reported that number to be at 16.5 percent.

The number of sleep-related crashes may even be higher than reported because there is no measurable test to determine if fatigue was the cause of the crash. Investigators often piece together circumstances involving the accident to decide whether drowsy driving played a role. According to the National Highway Traffic Safety Administration, characteristics of a crash involving drowsiness include a lone driver, a high-speed road and no attempt to avoid the crash.

How Does Sleepiness Affect Driving?

Some people may not even realize when they are too tired to drive. What may also be surprising is that even getting a little less sleep than normal can increase your risk of getting into a crash. A study released in 2016 by the AAA Foundation for Traffic Safety, indicated that drivers who slept one hour less than their normal amount were at an increased risk of getting in a car accident. Drivers who sleep less than seven hours in a 24-hour period and those who routinely get less than five hours of sleep a night also have higher crash rates.

There are several reasons your risk of accidents increase when you’re sleepy. Lack of sleep may have the following effects:

Slowed reaction time: Reaction time and accuracy declines when you’re sleep deprived. When you’re driving, you may have to make split second decisions. Even a brief delay can mean the difference between avoiding a crash and getting into an accident.

Poor judgment: When you’re tired, your judgment may not be at its best. So how does that affect driving? You may have decreased vigilance and be more likely to take risks. For example, you might be more likely to think you have time to make a yellow light or have room to pull out in front of someone.

Increased aggression: We all know when we are sleep deprived we are more likely to get cranky. When you’re driving that may mean you’re less tolerate and more likely to drive aggressively.

Signs You’re Too Sleepy to Drive

Sometimes you just know you are way too sleepy to drive, but push through to get where you need to be. But there may also be other instances when you don’t recognize the signs that you are too fatigued to drive, so you keep going. Signs you may be too sleepy to drive include:

  • Yawning frequently
  • Problems remembering the last few miles. For example, not being aware of how you got from point A to point B
  • Drifting from your lane or hitting the rumble strips
  • Catching yourself closing your eyes
  • Heavy eyelids

Staying Awake at the Wheel

Each day thousands of drivers get behind the wheel and zip down the road when they are sleepy, which puts us all at risk. We each can do our part to prevent driving drowsy. Consider some of the following tips:

Know when enough is enough: It’s essential to admit to yourself when you’re too tired to drive. If you start feeling sleepy and are having a hard time staying alert, it’s time to stop driving. In some cases, that may mean finding a safe place to pull off the road and rest or stop driving for the night. Trying to push through sleep deprivation on the road could be a fatal mistake.

Stop and stretch: If you are on a long drive, taking frequent breaks, such as every two hours, can be helpful in keeping fatigue at bay.  

Avoid medication that may cause drowsiness several hours before driving: Be aware of the side effects from certain medications, such as antihistamines or pain medicine. If you take medication that tends to cause drowsiness, do not attempt to drive. 

Consider the buddy system: On long drives, use the buddy system if possible. Switch off driving with your friend or family member every few hours.

Get treated for sleep disorders:  Nothing prevents drowsy driving better than getting a good night’s sleep. It’s difficult to get restful sleep if you have a sleep disorder. If you suspect you have a sleep disorder, talk to your doctor about scheduling a sleep study and get the treatment you need.

Don’t rely on tricks to stay alert if you are drowsy: Certain tricks to stay awake, such as opening the window or turning up the music, should not substitute for adequate sleep. Tricks may help you feel more awake and alert for a few minutes, but they are unlikely to have any significant effect on your ability to stay awake.

Drowsy Driving FAQ

How many accidents happen each year due to sleepy drivers? According to the National Highway Traffic Safety Administration (NHTSA), over 70,000 crashes were thought to be caused by drowsy driving in 2013. But that number may be higher.

Who is most at risk for drowsy driving? Anyone who does not get enough sleep is at risk for drowsy driving. But according to the CDC, people who work the night shift, are commercial drivers or have an untreated sleep disorder are more likely to drive drowsy.

When are crashes related to sleepy drivers most likely to occur? Crashes involving drowsy drivers can occur at any time. But according to the NHTSA, crashes due to drowsiness are more likely to occur early morning or late at night.

How can I manage fatigue on the road? If you find yourself feeling too sleepy to drive, your best bet is to find a safe place to pull off the road and get some rest. Remember, driving drowsy is risky. It’s better to err on the side of caution, so you get to your destination in one piece.

Author: MaryAnn DePietro, CRT is a medical writer and licensed respiratory therapist with over a decade of clinical experience.


AAA Foundation for Traffic Safety. Acute Sleep Deprivation and Crash Risk. https://www.aaafoundation.org/acute-sleep-deprivation-and-crash-risk   Retrieved May 2017.

Centers for Disease Control and Prevention. Drowsy Driving; Asleep at the Wheel. https://www.cdc.gov/features/dsdrowsydriving/   Retrieved May 2017.

National Highway Traffic Safety Administration. Drowsy Driving and Automobile Crashes. https://one.nhtsa.gov/people/injury/drowsy_driving1/Drowsy.html#NCSDR/NHTSA    Retrieved May 2017

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