Imagine this: You're fast asleep when all of a sudden you're awoken!
And not by your alarm clock.
Your eyes open, and there's a demon sitting on your chest, pinning you down.
You try to open your mouth and scream, but no sound comes out.
You try to get up and run away, but you realize that you are completely immobilized.
The demon is trying to suffocate you, but you can't fight back.
You've awoken into your dream, and it's a nightmare.
It sounds like a Stephen King movie, but it's actually a medical condition called sleep paralysis,
and about half of the population has experienced this strange phenomenon at least once in their life.
This panic-inducing episode of coming face-to-face with the creatures from your nightmares can last anywhere from seconds to minutes
and may involve visual or auditory hallucinations of an evil spirit or an out-of-body feeling like you're floating.
Some have even mistaken sleep paralysis for an encounter with a ghost or an alien abduction.
In 1867, Dr. Silas Weir Mitchell was the first medical professional to study sleep paralysis.
"The subject awakes to consciousness of his environment but is incapable of moving a muscle.
Lying to all appearance, still asleep.
He's really engaged for a struggle for movement, fraught with acute mental distress.
Could he but manage to stir, the spell would vanish instantly."
Even though Dr. Mitchell was the first to observe patients in a state of sleep paralysis,
it's so common that nearly every culture throughout time has had some kind of paranormal explanation for it.
In medieval Europe, you might think that an incubus, a sex-hungry demon in male form, visited you in the night.
In Scandinavia, the mare, a damned woman, is responsible for visiting sleepers and sitting on their rib cages.
In Turkey, a jinn holds you down and tries to strangle you.
In Thailand, Phi Am bruises you while you sleep.
In the southern United States, the hag comes for you.
In Mexico, you could blame subirse el muerto, the dead person, on you.
In Greece, Mora sits upon your chest and tries to asphyxiate you.
In Nepal, Khyaak the ghost resides under the staircase.