How to tell if you're too tired to drive — and what to do if you are

Thirty-seven percent of people admitted to falling asleep behind the wheel. Here’s what to do to make sure you’re not one of them.
Image: Tired woman driving at dusk on a highway
Yawning, lane deviation and an inability to remember the last couple of exits or miles are sure signs you're too tired to be behind the wheel. Carlos Ciudad Photos / Getty Images
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By Brianna Steinhilber

Perhaps you were coming home from a tiring day at the beach with your family, commuting to work, or pushing through the last leg of a long road trip. Your eyes felt heavy and began to droop. And you fought off an endless series of yawns while struggling a bit to keep your eyes on the road.

Sound familiar? Reports show that for many of us it does. This year, AAA reported that the number of crashes involving drowsiness is almost eight times higher than federal estimates indicate. And according to the National Sleep Foundation’s Sleep in America poll, 60 percent of adults admitted to driving drowsy and 37 percent admitted to having fallen asleep at the wheel. A more recent Sleep Health Index put out by the foundation found that 3 percent of Americans — which would equate to 7 million people — admitted to falling asleep at the wheel within a two-week period.

It may be an alarmingly common experience, but it’s one that Maureen Short, a Human Factors Expert and Senior Safety Engineer for Chevrolet, hopes to reduce.

Being awake for 18 hours straight makes you drive like you have a blood alcohol level of .05.

“We want people to understand how dangerous it is to drive drowsy,” Short told NBC News BETTER, especially during the summer when kids are out of school and people are more likely to take long road trips. “Drowsy driving causes a few things: one, you’re going to have a delayed reaction, and that is critical when you’re driving ... to be able to respond if you have an unexpected event. The second thing is that your decision making is impaired.”

In fact, The National Sleep Foundation reports that sleep deprivation can have similar effects on your body as drinking alcohol. "Being awake for 18 hours straight makes you drive like you have a blood alcohol level of .05 (for reference, .08 is considered drunk)," they report. "If you’ve been awake for a full 24 hours and drive — say, after a night where you just couldn’t fall asleep — it’s like you have a blood alcohol level of .10."

Maureen Short conducted a drowsy driving simulation at Citi Field in Queens, NY on June 14, 2018.

To help spread awareness about the dangerous effects that fatigue can have on drivers, Short is travelling to a few cities this summer conducting drowsy driving simulations. During the simulation, participants don a 23-pound suit and goggles that replicate how your body feels when you are driving in a drowsy state, including delayed blinking patterns, sluggishness and extreme tiredness.

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“The simulation goggles change the way your eyes close and really give you the idea of what it’s like to drive while drowsy,” says Short. “As you get tired, the way we can tell is by your percent of eye closure, so every 10 seconds, the goggles close for one second; this represents being a medium level of drowsy, and mimics your eye pattern when you’re tired. If you’re truly drowsy and you nod off, it can be 2-4 seconds of eye closure at a time.”

The weighted suit works to slow your reaction time, similar to how it is slowed when you're tired. "When that reaction is slowed, you don’t always feel the effects," says Short. "Unfortunately, drowsiness doesn’t just happen quickly; it happens over time.”

I suited up and took part in the simulation when Short set up shop in the parking lot of Citi Field in New York city earlier this summer. It was definitely unnerving (to say the least) to have my field of vision obstructed every 10 — and then every 4 — seconds. When told to turn either left or right at the last minute, having a reduced field of vision slowed my decision making skills — and then I had a delayed reaction time once I did decide which way to turn, thanks to the weights on my ankles and wrists.

While I attempted to navigate the course, Short reminded me that while we were driving on a closed course going just 15-25 miles per hour, on the highway, you’re driving 60 to 70 miles per hour and covering a lot more area, which really increases the risk.

4 signs that you’re too tired to be behind the wheel

Reducing the occurrence of driving drowsy starts with being able to recognize the signs that you may be too tired to be behind the wheel. Short says to look out for these commons signals that our bodies are fatigued and our ability to drive may be impaired:

  • Yawning. Continually yawning or the inability to keep your eyes open. Yawning is one of the simplest indicators to signal that you're tired, Short says.
  • Memory lapse. “If you don’t remember the last couple of exits or last couple of miles, you’re getting tired and need to stop,” she says.
  • Lane deviation. If you’re starting to go back and forth in the lane, drifting from lane to lane and/or engaging the rumble strips on the side of the road, it's time to pullover.
  • Unsafe driving maneuvers. Frequent tailgating, braking or other unsafe driving maneuvers are a sign you may be dozing off, especially if active safety features (like lane keep assist, lane departure warning and others) have been engaged more than average.

Strategies to help you get home safe

We’ve all tried to power through that last 30 minutes of a long journey or had too early of a start in the morning when we're still groggy. Short encourages us to recognize when we're too tired to drive and not get behind the wheel in the first place. When you do recognize the symptoms above, "number one is always to get off the road,” says Short. But until you can, there are some strategies you can use to help keep yourself alert.

  1. Call someone. “Call a friend, call your mom, or if you are in a vehicle with other passengers wake them up and have them talk to you, and really get your mind engaged," says Short.
  2. Take advantage of the safety systems in your car. Many cars come equipped with features designed to keep you safe on the road. “Turn on your active safety systems," says Short. "At Chevy, we have lane departure warning and lane keep assist, those will help you stay in the lane. And forward collision alert. Give yourself enough time as possible to make a decision."
  3. Play mental games. Anything that gets your brain engaged mentally will help you stay alert. "If you start to feel your mind wander, go old-school and play eye-spy, 20 questions or the billboard alphabet game," says Short. "Engaging your mind can often help you stay alert, so you can focus on the road ahead."
  4. Consider a nap. AAA says to not underestimate the power of a quick nap. If you’re on a longer drive or road trip, pulling into a rest stop and taking a quick catnap — at least 20 minutes and no more than 30 minutes of sleep — can help to keep you alert on the road, they say.
  5. Don’t rely on quick fixes. Short stresses not to rely on energy drinks or coffee to power you through your trip. There is no better way to tackle tiredness than getting the recommended amount of sleep, she says. If you’re too tired to focus, consider pulling over in a safe place for a nap or find the nearest hotel to get a good night’s rest, she says. “Don’t be fooled, the only antidote for drowsiness is sleep,” said William Van Tassel, manager of Driver Training for AAA. “Short term tactics like drinking coffee, singing, or rolling down the window will not work. Your body’s need for sleep will eventually override your brain’s attempts to stay awake.”


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