You’re driving along a desolate stretch of highway and note a road sign announcing your destination is 62 miles away. The next thing you know, you’re blinking at another sign, one that says you have 40 miles to go.

You’re sure you didn’t fall asleep behind the wheel. After all, you didn’t crash or cause an accident. But what happened to those 22 miles?

Maybe you’ve experienced something similar while driving through town. Coming to a halt at a red light, you realize you can’t recall the last several minutes of your drive. Did you use your turn signal? Stop at stop signs? Follow the speed limit? You have no idea.

Both of these are examples of highway hypnosis, a phenomenon that causes you to go into a trance-like state while driving.

The monotony of the road slows down your brain, leaving you less alert and functioning on autopilot.

You may not always realize when highway hypnosis takes over — at least, not until you’ve snapped out of it.

Some warning signs you might notice include:

If you suddenly realize you’ve just passed your freeway exit or you can’t remember anything about the last several miles, you’ve probably experienced highway hypnosis.

Other telltale signs include catching yourself drifting into the next lane or driving onto the rumble strip.

Another person in the car with you might also notice you have a blank expression or glassy-eyed stare.

While highway hypnosis can happen more commonly in tired drivers, fatigue isn’t the only cause.

Here’s a look at some major contributing factors.

Monotonous roads

Most existing research on highway hypnosis suggests monotony plays a significant part in this phenomenon.

A 2003 study used a driving simulator to study the effects of road monotony on 56 experienced male drivers. The participants “drove” on two different simulated roads for 40 minutes at a time.

Both roads were flat, but the first road only had one type of visual scenery: pine trees spaced equally on either side of the road.

The second road contained multiple visual elements, including trees, farms, signs, and people. Flat bridges and overpasses also broke up the scenery in several different places.

Researchers found that the drivers tended to show more fatigue, measured by large steering movements, while driving on the more monotonous road.

Also noteworthy was the fact their fatigue peaked after approximately 20 minutes of driving. This suggests highway hypnosis may happen very quickly on monotonous stretches of road, not only after long periods of driving.

Brain inattention

According to other research from 2004, your oculomotor system, or the system that controls eye movements, also plays a part in highway hypnosis.

When you drive along a road you know well or stare at a largely unchanging road for a long period of time, your brain begins to depend less on retinal feedback, or what you actually see. Instead, your brain begins to depend more on your mental prediction of what you’ll see (extra-retinal feedback).

In other words, your brain switches to a less-alert mode and begins to pay less attention to visual stimuli.

Sleepiness

The likelihood of experiencing highway hypnosis does go up when you’re tired.

The monotony of the road can lower brain alertness, but so can fatigue. In either case, your brain processes what you see more slowly than usual, relying on mental predictability and autopilot instead.

Other factors, including road monotony, the blurring white lines, and trees stretching endlessly toward the horizon, can combine with drowsiness to lull you into a trance-like state, even if you don’t actually fall asleep.

Fatigue can also get worse if you keep driving. Longer time spent driving can increase your chances of experiencing highway hypnosis and even make it more likely you will fall asleep.

If you start to notice the warning signs of highway hypnosis, try these tips to increase your alertness.

Take a break

The longer you spend on a monotonous task, the more likely your brain will switch to autopilot mode.

If you zone out over some documents at work, the worst that will happen is you’ll just have to read them again. When this happens on the road, you put yourself and any nearby drivers at risk.

When planning a driving trip, make sure you allow enough time for a stop every hour or two. Get out of your car and move around as much as possible. Go for a brisk walk, or run in place.

If you feel tired but need to keep driving, a short nap can help you recharge.

Have some caffeine

If you feel sleepy while driving, caffeine can help boost alertness, but it might not be enough to keep you awake entirely.

Even if you don’t feel sleepy, taking sips of a drink or having a snack can help break up the monotony of driving. Just make sure it’s not something too distracting or difficult to eat.

Talk or sing

Talking to someone can help keep your brain engaged. If you can’t safely use a hands-free device to call a friend while driving, get off the road as soon as you can, and then connect the call.

If you know you have to drive for a long time, try making plans with a loved one ahead of time so you can make sure they’re available for a call.

It’s also totally fine to talk to yourself.

Remember those poems and dramatic monologues you had to memorize during high school English? Trying to dredge those up from the depths of your memory can give you something to concentrate on.

You can also try solving a math problem out loud, singing your favorite songs from memory, or talking through a problem that’s been on your mind.

Make some environmental changes

When you feel highway hypnosis coming on but don’t have a chance to stop for a while, these quick internal adjustments can help you shake it off:

  • Put on loud, upbeat music or engaging talk radio. Avoid anything that could make you feel sleepy or less attentive, such as soft, slow music or droning voices.
  • Roll down the window. A warmer environment can increase drowsiness and inattention, so roll your windows down, or turn on the air conditioning. If you’re driving at a high speed, the wind in your face can help keep you feeling sharp.
  • Turn off cruise control. Monitoring your speed can help prevent highway hypnosis by giving you something important to concentrate on.
  • Drive with an upright seat. Putting your seat up straight before you leave can help you maintain good posture while driving, making it less likely you’ll slip into an overly relaxed state.

Sometimes you just have to take that long, boring drive. Preparing yourself with these strategies can help you avoid highway hypnosis.

Try a new road

If you regularly drive the same long distance, such as when commuting to work in a different city, changing up your route can help you avoid highway hypnosis.

If possible, try:

  • driving through town instead of using the highway
  • getting off at a different exit
  • finding alternate highway routes

Eat lightly

Imagine how you feel during the afternoon after having a big lunch at work. A little drowsy, a lot less alert?

If you have a large meal before getting in your car to take a long drive, you’ll probably feel much the same way.

Have a light meal instead, and pack a few snacks for the road. Remember, produce and light proteins can keep you more alert than sugar and heavy carbs.

Make an all-new playlist

Switching on the radio won’t always keep you alert while driving. If you don’t like what’s playing, or the music is too soft and slow, you might feel even less engaged.

The next time you need to take a long drive, prepare a playlist of new material to replace your favorite hits.

Add music you haven’t yet listened to and new episodes of podcasts you enjoy. Download the audiobook version of a book you’ve been planning to read.

Paying attention to new content may help keep you more alert than listening to the same things you usually listen to (even if you really love them).

Get enough sleep

Highway hypnosis is more common in tired drivers. Making sure you get enough sleep before hitting the road may help lower your chances of zoning out (or drifting off) while driving.

It’s also wise to check the labels of any medications you’re taking to make sure they don’t cause drowsiness. If they do, you might want to ask your healthcare provider about briefly discontinuing them so you can drive safely. (But don’t stop taking any medications without their approval.)

Driving at night may increase the likelihood of experiencing highway hypnosis or falling asleep behind the wheel, so try to drive during the day whenever possible.

While you might be technically awake and operating on autopilot, highway hypnosis still leaves you less than fully alert, so it could have serious consequences.

It’s pretty common to fall under the spell of a long and boring road, but you can lower your risk by taking steps ahead of time to keep yourself more alert.

Crystal Raypole has previously worked as a writer and editor for GoodTherapy. Her fields of interest include Asian languages and literature, Japanese translation, cooking, natural sciences, sex positivity, and mental health. In particular, she’s committed to helping decrease stigma around mental health issues.