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The True Dangers of Driving When You’re Sleepy

You know you’re tired. Whether you stayed up too late scrolling through your Instagram feed, worries about work kept you awake or you were lying in bed waiting to hear the sound of your teenager coming home, let’s face it—there are nights when you just don’t get enough sleep. 

The next day, you’re on the road, yawning behind the wheel and hoping the caffeine in your morning coffee will give you the boost you need to stay alert. How dangerous is it to drive when you’re sleep-deprived, and what are the risks of drowsy driving really?

Why it’s dangerous to drive when you’re sleepy

Drowsy drivers are a public health concern, according to the National Sleep Foundation. Drowsy driving causes 100,000 accidents, 71,000 injuries and more than 6,400 deaths a year in the United States. They report that people who get less than two hours of sleep in the past 24 hours are not fit to drive, and people who have slept three to five hours are still impaired.

We talked to Sanjay Kaji, MD, a sleep medicine specialist with Banner – University Medicine, to learn more about the risks of fatigue on the road. “When you drive when you’re tired or drowsy, you may have trouble paying attention, slower reaction times, trouble making good decisions and a higher risk for accidents,” he said. 

Your brain simply doesn’t function as well when you’re sleepy. Your attention, concentration and reaction time all suffer. Your judgment is impaired, so you’re not as good at making decisions. 

You’re at higher risk of falling asleep at the wheel and getting into an accident. Your ability to drive is impaired. You can’t control your vehicle as well, and you’re more likely to drift out of your lane. You won’t respond to unexpected situations as quickly. 

Driving when you’re tired is like driving when you’ve been under the influence of alcohol. In fact, the Sleep Foundation reports that being awake for 20 hours is comparable to having a blood alcohol level of .08%, which is the legal limit in most states.

Watch for these signs of fatigue

You may not realize how tired you are behind the wheel, especially if you’re driving long distances. As you get sleepy, you may notice these signs of drowsy driving:

  • Yawning
  • Trouble keeping your eyes open
  • Difficulty focusing 
  • Frequent blinking
  • Difficulty keeping your head up
  • Nodding off
  • Daydreaming or trouble remembering the past few miles
  • Missing traffic signs or your exit or turn
  • Trouble maintaining a consistent speed
  • Drifting in and out of your lane
  • Swerving
  • Driving onto a rumble strip on the side of the road
  • Tailgating
  • Feeling irritable, restless or aggressive

How to prevent drowsy driving

“It’s important to make sure you get enough sleep consistently. Develop good sleeping habits and have a regular sleep schedule,” Dr. Kaji said. Most adults need seven to nine hours of healthy sleep in 24 hours to be well rested, and teens need eight to ten hours. Shift workers need to be especially careful about maintaining good sleep habits since they don’t always have a regular sleep-wake cycle. 

You need to get this much sleep regularly—you can’t make up for lost sleep. If you often feel as though you’ve slept enough, but you’re still tired, you could have untreated sleep apnea or another untreated sleep disorder. Talk to your doctor about your symptoms.

These tips can help you stay awake:

  • Be cautious with caffeine. The amount of caffeine in a cup or two of coffee can help you stay alert, according to the National Safety Commission. But drinking a lot of coffee or energy drinks can make you excited, agitated and aggressive behind the wheel. You shouldn’t use these drinks to compensate for a night of bad sleep—you can become disoriented and have slower reaction times. Plus, you may not realize how exhausted you get when the effects of caffeine wear off. 
  • On road trips, it can be tempting to push through and get to your destination as quickly as possible. Be sure to plan for fatigue on the road—taking regular breaks is important. Stop for 10 to 20 minutes every two hours and for at least 45 minutes after you’ve been on the road for four to five hours. If you can, bring another driver and take turns driving. 
  • Drive during regular waking hours. Driving at times when you should be sleeping is risky. Crashes occur most often between midnight and 6 a.m., according to the National Highway Traffic Safety Administration. The late afternoon is another risky time—you have a dip in your circadian rhythm, which regulates your body’s sleep cycles, at both times of day. 
  • Always take a break if you feel tired or drowsy.
  • Be careful about driving when you’re jet-lagged. Crossing time zones can throw off your cycles of sleep and wakefulness.
  • Avoid driving if you take medications or substances that can make you drowsy as a side effect. Check the labels on your medications to make sure they don’t cause drowsiness.
  • Avoid drinking alcohol before you drive. Alcohol consumption impairs your ability behind the wheel.

What to do if you’re too tired to drive

It’s tempting to get behind the wheel when you’re sleepy. After all, driving is often the fastest and most convenient way to get where you need to go. But it’s simply not safe to drive when you’re drowsy. Consider:

  • Taking a rideshare
  • Carpooling
  • Using public transportation
  • Asking a friend or family member to give you a ride
  • Rescheduling your plans to another day

The bottom line

If you drive when drowsy, you’re putting yourself and others at risk of injury or death. Be sure to get enough rest before you drive and watch for signs of drowsiness on the road. If you have trouble getting restorative sleep,  a sleep medicine specialist can help. Reach out to Banner Health to get the care you need.

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