What’s Happening In Your Brain During ‘Microsleep’

We’ve all experienced it: You’re completely exhausted after pulling an all-nighter, and despite your best efforts to stay awake, your eyelids keep closing and closing until suddenly you nod off for just a second — only to awake with a jerk.

This phenomenon is what’s known as “microsleep,” 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.

Why does our brain enter these periods of microsleep? They’re typically caused by extreme fatigue. 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. 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.

Here’s a look at the science of microsleep — and why it can be so dangerous.

It’s your brain’s losing struggle between sleep and wakefulness.

In the battle to stay awake, sometimes your brain loses. A study published in the journal Neuroimage investigated microsleep by keeping a group of volunteers awake for 22 hours. The volunteers were then put in a dark fMRI machine and asked not to fall asleep. The brain scanner detected when they nodded off periodically, and looked at what was going on in their brains. During these bursts of microsleep, there was reduced activity in the thalamus, a region of the brain involved in regulating sleep.

Interestingly, there was also increased activity in brain regions responsible for sensory processing and paying attention — functions that are, of course, critical to wakefulness. This suggests that parts of the brain are in “waking” mode while other areas temporarily succumb to the —> Read More