Microsleep Causes and Dangers

What Happens When You’re Awake, but Your Brain Goes to Sleep?

The difference between being awake and asleep isn’t as clear-cut as you may think. It’s called microsleep, and it may put you at risk.

Microsleep is dangerous

You’re driving home after a long day of work, and suddenly, you realize that you don’t remember the last mile. You can’t recall if the light was red or green when you went through the intersection. Maybe you even missed your turn. Sound familiar? If so, you’ve experienced microsleep. And the dangers it can bring.

What Is Microsleep?

Microsleep is a brief, involuntary episode of unconsciousness lasting anywhere from a fleeting moment up to several seconds.

During this rather bizarre state, your eyes may be open, you can be sitting upright and you might even be performing a task, but certain areas of your brain have gone completely offline. In other words, you may think you’re awake, but parts of your brain are actually asleep.

“We often use phrases like “zoned out” or “autopilot” to describe microsleep,” said Mary Helen Rogers, vice president of marketing and communications for the Better Sleep Council. “That’s pretty accurate, since we’re not functioning at our full mental capacity during these periods of time.”

What Causes Microsleep?

Microsleep happens without warning, at any time of the day, most often when you are already sleep deprived. Research shows that even a single night of insufficient sleep can result in increased microsleep episodes.

But it’s not just fatigue from a poor night’s rest that causes our brains to check out. Microsleep is also closely associated with performing a boring, monotonous task. For example, one study published by the National Center for Biotechnology Information had well-rested participants use a joystick to track a moving target on a computer screen for 50 minutes. On average, subjects experienced 79 episodes of microsleep that lasted up to 6 seconds each during the experiment. That’s a lot of zoning out in just 1 hour.

Why Is Microsleep Dangerous?

“The big issue with microsleep is that we’re much more likely to make critical mistakes in this half-awake, half-asleep state,” added Rogers.

During microsleep, scientists have been able to measure localized areas of the brain switching to slow-wave, sleep-like activity. The thalamus, in particular, becomes less active. Since the thalamus is responsible for interpreting incoming sensory signals, your reaction time and ability to pay attention suffers.

Many fatal accidents (2016 London tram derailment) and tragic disasters (1986 Chernobyl nuclear accident) have been linked to microsleep. That doesn’t include the host of minor fender benders and countless products that have come off the assembly line missing screws.

Can You Avoid It?

The best way to prevent microsleep is to get enough quality sleep each night for you to function throughout the day and not feel fatigued. But when you still have to do repetitive tasks, like drive long distances, operate heavy machinery or just work an 8-hour shift of data entry, you can try some of these tips to stave off potential misteps or accidents caused by microsleep:

  • Take a power nap. A short, 20-minute siesta can recharge your brain so you are more alert for a longer period of time.
  • Take a break. Changing what you’re doing for a few minutes every half-hour or so activates different parts of your brain to reduce the monotony. Better yet, get up and move around during your break to get your blood flowing.
  • Have a lively conversation. Chatting forces you to concentrate on the back-and-forth of a discussion. Plus, talking increases your breathing rate, which puts more oxygen in your bloodstream.
  • Turn up the tunes. Loud, upbeat music can lift your mood. If you’re alone or in good company, feel free to sing along.
  • Have some caffeine. Just remember, it takes about 30 minutes for the stimulation to kick in. And don’t have too much too close to your normal bedtime; you might not fall asleep and end up feeling even more tired tomorrow.
Zoned out? On autopilot? Even when you’re awake, parts of your brain can actually fall asleep. Learn more about microsleep from @BetterSleepOrg.


This blog provides general information about sleep and sleep products. The words and other content provided in this blog, and in any linked materials, are not intended to replace a one-on-one relationship with a qualified heath care professional. This blog should not be construed as medical advice or used to diagnose, treat, prevent or cure any disease or condition. If the reader or any other person has a medical concern, he or she should consult with an appropriately-licensed physician or other health care professional. This blog is not a substitute for professional medical advice, diagnosis or treatment, and should not be relied upon to make decisions about your health or the health of others. Never disregard professional medical advice or delay in seeking it because of something you have read on this blog or elsewhere on bettersleep.org. If you think you may have a medical emergency, immediately call your doctor or dial 911.

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