We’ve all been there. Maybe you’re reading a dull book on the couch. Maybe you’re listening to another boring HR presentation at work. Maybe you’re driving late at night on an empty stretch of road. Your eyelids start to get heavy. Your attention fades. And then suddenly you feel your head jolt.

Microsleep The Battle between Sleep and Wakefulness

It isn’t until your head jolts that you realize you were actually asleep for a few seconds. That is called microsleep. Microsleep is defined as “a momentary and involuntary pocket of temporary unconsciousness lasting from a fraction of a second up to roughly 10 seconds, ending in a sudden head jolt.”

When you’re having a microsleep episode, whether it lasts for two seconds or ten, you stop responding to your external environment. For example, you would not notice that your boss is giving you the eye or that the road you’re driving on is about to take a sudden turn. Interestingly, most people would never even be aware that they’d had a microsleep episode were it not for the head jolt at the end. In fact, most microsleep occurs with your eyes open in a blank stare.

Microsleep is more likely to happen during the times of the day when your body wants to be sleeping, such as early in the morning or late at night. More importantly, though, it happens when you’re extremely sleep deprived.

“Sleep is a basic biological necessity, and when we force ourselves to go without it for too long, the brain will eventually shut down — even if just for a few seconds,” according to the Huffington Post. “During microsleep, your brain is essentially taking a forced nap, because its current level of sleep deprivation is preventing certain areas and networks from functioning.”

A study published in the journal Neuroimage conducted research on what exactly is going on in your brain when you are sleep deprived but trying to force yourself to stay awake. Some parts of the brain behave in the same way they would if you were getting into bed for the night while others reflect the tug-of-war between sleep and wakefulness.

This makes a certain amount of logical sense, because you are essentially engaging in a battle between your willpower to stay awake and your biological need to sleep.

One of the areas where the researchers saw an increase in activity was the part of the brain that is associated with sensory processing. The researchers suggested that this could explain why we sometimes have very vivid dreams during these microsleep episodes or when we first fall asleep at night.

This “tug-of-war between sleep and wakefulness” can be really dangerous. On the one hand, if you’re just reading a book on the couch and you find yourself dozing off, you might just settle deeper into the cushions for a nice nap. But if you’re driving a car, the implications of microsleep can be fatal. In fact, over the last decade, more than 7,000 people have been killed in drowsy-driving-related crashes, according to the National Highway Traffic Safety Administration (NHTSA).

The solution is simple: sleep. Make sure you get 7 or 8 hours of sleep each night, especially if you know you have to be particularly alert the next day. If you’re driving and you feel yourself getting drowsy, pull over at a gas station and buy something with caffeine in it. Caffeine actually takes about 20 minutes to kick in, which is the perfect amount of time for a refreshing nap before continuing on your way. Wherever you’re going, it’s better to arrive alive.