What do you think of this fact?
You wake up at night, eyes open, but you can’t move a finger. Something is pressing down on your chest. And someone is standing in the corner of the room. It sounds like the opening of a horror movie, but it has a name: sleep paralysis.
Awake at the wrong moment
During REM sleep, the phase with the most vivid dreams, your muscles are almost completely paralyzed. That’s useful, because it stops you from acting out your dreams in bed. Sometimes, though, your mind wakes up before that paralysis wears off. Then you’re awake and still can’t move.
According to the Sleep Foundation, an episode usually lasts from a few seconds to a couple of minutes. Many experts think dream imagery spills over into the waking state. Up to 75 percent of episodes come with hallucinations.
The visitor on your chest
Two versions are especially common. In the “intruder” type, you sense or see a menacing figure in the room. In the “incubus” type, it feels like someone is sitting on your chest. One possible explanation: breathing gets shallower in REM sleep, and if you suddenly notice that, it feels like pressure.
No wonder almost every culture has a character for it. Medieval Europe had the night-mare, a being that sat on sleepers. Newfoundland talks about the “Old Hag”, Brazil about the Pisadeira, Japan about kanashibari.
A painting made of goosebumps
In 1781, Henry Fuseli painted “The Nightmare”. A demonic creature crouches on the chest of a sleeping woman while a horse’s head peers out from behind a curtain. In 1782 it was shown at the Royal Academy in London and became Fuseli’s first big success. Today it hangs in the Detroit Institute of Arts.
In the 1920s, an engraving of the painting hung in Sigmund Freud’s apartment in Vienna.
So how common is it? A review of 35 studies found that 7.6 percent of the general population and 28.3 percent of students have experienced it at least once. Across all studies, it was about 20 percent.
So the demon on your chest is pretty common. It just has the worst timing in the world.