Ghosts in Your Bedroom?—It's Probably Sleep Paralysis

You wake up out of a hazy sleep and you can’t move your body—you’re completely paralyzed! You also have this oppressive feeling in your chest, as if something heavy is sitting on it, and an eerie sense that someone's in the room with you. Your heart pounds, and everything spirals, becoming more and more unreal as you scream silently inside.

Is this a great horror movie scene, or something more sinister?

What is sleep paralysis?

Different cultures have explained this frightening experience in various ways. In Brazilian folklore, a crone with long fingernails lurks on roofs and tramples on sleepers’ chests. In Japanese mythology, vengeful spirits come to suffocate their enemies while they sleep. For Canadian Eskimos, it’s the spells of shamans that paralyze the sleeper while giving them hallucinations. In contemporary American culture, sleep paralysis has taken on the mythology of alien abductions—sleepers wake up unable to move, seeing or feeling the presence of aliens in the room while experiencing zapping sensations and a feeling of suffocation. 

But it turns out all of these symptoms describe sleep paralysis, a sleep disorder (or symptom of a sleep disorder) that temporarily alters a person’s mobility, perception, thinking, and emotional state during the transition between sleeping and waking.

Sleep paralysis is a surprisingly common experience—almost 8% of the general population has experienced it at least once. But if you’re a student or someone with a psychological diagnosis, your chances of experiencing it go up to almost 1 in 3.

But rest assured, sleep paralysis is usually harmless, especially if it only happens rarely. But why does it happen at all, when should you worry about it, and how can you prevent sleep paralysis?

Why does sleep paralysis happen?

The “paralysis” part of sleep paralysis actually happens every night when you sleep, even though you're usually not aware of it. That’s because of a special type of sleep called rapid eye movement or REM sleep.

During REM, your brain is very active—the electrical signals from the brain look almost like the signals it has when you’re awake.

REM sleep is often referred to as a stage of sleep that takes up 20-25% of your typical night. It occurrs in a few chunks, mostly during the second half of the night. During REM, your brain is very active—the electrical signals from the brain look almost like the signals it has when you’re awake. This is also when most dreaming happens, along with a lot of emotional processing that the brain does behind the scenes.

But, importantly, your body is immobilized during REM. Other than the eyes moving around a lot (hence...

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