Microsleep: What is it, symptoms and dangers of sleep deprivation

Microsleep is such a common that many don’t even realize the real-life dangers of it. It is one thing to doze off in class for a minute after pulling an all-nighter and writing that 10-page paper. It is a completely different thing to miss a red light when you are driving. I’m sure you have experienced it. It happens to the best of us. Learn more about what is it, its symptoms and its dangers by reading this complete guide. 


What is a microsleep?

You might have not gotten enough sleep the night before and you are on the underground on your way to work. Everybody around you looks tired and miserable because it’s 7:00 on a Monday morning. Not too much to be happy about. You manage to get a seat on one of the stops and find yourself squeezed in between two people you will never see again in your life. At first, you are watching people around you and even trying to read the newspaper a guy across from you has. The advertisements on the walls are the same as they’ve been for weeks and they do not catch your attention in the slightest. In fact, you could probably recite the advertised words in your sleep.

The headphones in your ears are playing some famous song but the sound slowly becomes distant. The words on that newspaper in a guy who is sitting across from you become blurry. Your eyelids start to close and you are semi-aware of it. You don’t stop it though. Your head bobs down and you wander off into a moment of oblivion. Suddenly the loud speaker announces the next stop and your head jerks up, you open your eyes and start blinking, get up and exit the subway.

You might not be aware of it and it might have happened to you on many different occasions. In class, with your teacher lecturing in a monotone voice, at work you’re your boss is presenting the new strategy for a project. You might even doze off in a line to the cafeteria. Some people experience fatigue a lot more often than others but, in the end, it happens to all of us.

What you have experienced is what scientists nowadays call microsleep. It seems painless, falling asleep for a moment due to the fact that you didn’t get enough sleep the night before. What you might not know, however, that it can be quite dangerous. Imagine, this microsleep catches up to you when you are not on the subway at 7:00 on a Monday morning. Imagine that you are driving to work at 7:00 on a Monday morning and you are experiencing those same fatigue symptoms.

Because you are not on a subway and you are the one controlling the vehicle, you can imagine what might happen if you doze off for a second or two. In fact, it’s probably happened before. And it happens on quite a regular basis to many drivers in the world. Sleep deprivation can cause these microsleeps. And the consequences of these microsleeps can be quite detrimental with the growing possibility of getting into a car crash.

Microsleep is a phenomenon that can last up to about 30 seconds. People who experience microsleep will note that they lose consciousness for a moment and that period of unconsciousness will end with a head jerk. The head jolt is usually the only way people know they’ve dozed off. Usually, it takes a brain about a minute or two to recognize that you are asleep. Microsleep does not last for such a long period of time. In fact, during moments before the ‘nap’ happens your brain is trying to keep you awake, however, ultimately loses the battle to fatigue and succumbs to the microsleep.

Symptoms of a microsleep episode

  • When people start dosing off, their head usually drops down. Jerking of the head back up signifies the end of the microsleep and is usually when you might know you’ve just experienced one.
  • Another sign of a microsleep might be an appearance of a blank face accompanied by an empty stare. People might find themselves blinking quite frequently but their eyelids feel heavy and stay closed for longer periods of time.
  • If you are not able to remember the previous moment, it could be due to the fact that you just experienced a microsleep episode.
  • As mentioned before, sudden jerk signifies the end of the microsleep. Sometimes it’s not only the head that jolts, but the entire body does so as well.
  • Microsleep is a lot more likely to occur in the hours that you are accustomed to sleeping or your energy levels start dropping. That’s why the before-work hours or the mid-afternoon hours are the most dangerous ones for episodes of microsleep. This has to do with the circadian rhythms of the body, or as we call it the biological clock. Our body knows when we should be sleeping and it tries to achieve that state by all means possible.

Microsleep causes

A lot of research has gone into figuring out microsleep and why it happens. It boils down to two simple things though, sleep deprivation and boredom.

Microsleep and Sleep deprivation

Individuals who are not getting enough sleep are a lot more likely to doze off involuntarily. In fact, microsleep works in a compensatory way to how much sleep that person has lost. This means that the longer you didn’t sleep for, the likelier your chance is to experience an episode of microsleep.

Microsleep and Boredom

Another reason for feeling sudden tiredness is boredom. You might be required to be completing a long task that requires the same type of repeated motions. On the other hand, you might need to be paying attention but the topic is so uninteresting to you or the method of delivery is dry and monotone, that you start dozing off automatically. That’s why when we think of sleep deprivation, we automatically think of students.

Population at risk of Microsleep

Young adolescents and young adults – those who are still currently in the education system – biologically require more sleep. Due to the lifestyle that the students follow and the amount of work that they need to handle, they often become sleep deprived. People with highly stressful jobs are at risk for sleep deprivation as well. Apart from that, those who suffer from sleeping disorders are a higher risk population for microsleep episodes. The most microsleep affects those people who suffer from sleep disorders that include periods of not being able to sleep.

Microsleep: what happens in the brain during an episode?

Studies have found that when people are sleep deprived and feel the constant need to take a nap, their brain actually starts falling asleep as well. Even though they still appear awake, their brain might be shutting down on them at those very moments. That’s exactly how we can classify sleep deprivation – being awake but our brain isn’t functioning properly.

Microsleep Research examples

Microsleep actually drives us unconscious for a few seconds. This means that we become unaware of where we are and what we are doing during an episode. This happens until that head jerk and that’s the moment we wake up again.

Various studies have explored the brain regions associated with microsleep episodes.

Brain regions involved in microsleep: thalamus, primary visual cortex & posterior cingulate cortex

In a 2009 International Conference, scientists presented the results of their study. In this study, they found fMRI BOLD signal in several regions of the brain. One of the regions was the bilateral thalamus. During the task, the activity in the bilateral thalamus decreased. It is quite interesting due to the fact that bilateral thalamus is usually one of the responsible parts of the brain for maintaining arousal and wakefulness.

A 2017 study looked at the brain regions during the microsleep episodes with the help of EEG, fMRI and other neuroimaging and experimental methods in hand. This study matched the results of the other study and showed that there was a decrease in thalamic activity. Apart from the decrease in that particular region of the brain, it also showed decreased activity in other parts. Not surprisingly, the primary visual cortex and the posterior cingulate cortex were one of the areas that decreased activity during the task. Both of these areas have a clear connection with the thalamus. Primary visual cortex receives connections from the thalamus and the posterior cingulate cortex is quite important in the periods of wakefulness and consciousness. That is why it’s not surprising that particularly those two regions of the brain showed decreased activity.

Another study, in 2007, put licensed drivers who suffer from sleep apnea into a driving simulation task while electroencephalography was recording their brain activity online. During microsleep episodes, the drivers slowed their speed down and had less of a control over the accelerator pedal. Also, worthy of noting, was the fact that the longer the sleepy drivers were a part of the simulation, the lesser control they had over the vehicle.

Dangerous consequences of microsleep

We can definitely see how microsleep can be dangerous to our everyday lives. Taking a nap during a task that requires our constant attention can be quite detrimental.

A lot of car crashes happened due to microsleep and people who doze off for just a few seconds and find themselves in the opposite lane or run a stop light.

1986 Chernobyl nuclear disaster that happened in Ukraine, devastated the lives of many people and left a ghost town in its wake, had proof of sleep-deprived workers.

Microsleep is dangerous by itself, but sleep deprivation can be more so. It slows reaction times, affects your critical thinking and decision making and has a toll on your judgment.

How to prevent the dangers of microsleep?

Get sufficient sleep!

It might sound silly but it’s the one point that makes all the difference. If you cannot get a night full of sleep, try to sneak in 20-minute power naps whenever you can and are not busy.

Do not drive!

When you are feeling sleepy: driving at night, for example, is quite dangerous. When you do go for a long road trip, bring a friend with you. Keeping the conversation going and listening to upbeat music might prevent you from dozing off.

Look out for warning signs!

  • Yawning
  • Poor concentration
  • Tired or sore eyes
  • Restlessness
  • Drowsiness
  • Slow reactions
  • Boredom
  • Feeling irritable
  • Making fewer and larger steering corrections
  • Missing road signs
  • Having difficulty staying in the lane

Capture your mind’s attention!

Try to find interesting and engaging things in everything that you do. It won’t only help with sleep deprivation, but might change your outlook on life in the meantime!


Poudel GR, Jones RD, Innes CRH, Watts R, Signal TL, Bones PJ. fMRI correlates of behavioral microsleeps during a continuous visuomotor task. In: Proceedings of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society: Engineering the Future of Biomedicine, EMBC 2009. 2009. p. 2919–22.

Poudel GR, Innes CRH, Bones PJ, Watts R, Jones RD. Losing the struggle to stay awake: Divergent thalamic and cortical activity during microsleeps. Hum Brain Mapp. 2014;35(1):257–69.

Boyle LN, Tippin J, Paul A, Rizzo M. Driver performance in the moments surrounding a microsleep. Transp Res Part F Traffic Psychol Behav. 2008;11(2):126–36.

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