Sleep paralysis was first identified within the scientific community by psychologist Weir Mitchell in 1876. He laid down this syntactically old-school, but accurate description of how it works. “The subject awakes to consciousness of his environment but is incapable of moving a muscle; lying to all appearance still asleep. He is really engaged in a struggle for movement fraught with acute mental distress; could he but manage to stir, the spell would vanish instantly.”
But the condition lived in folklore long before anyone tried to subject it to even semi-rigorous study. The various responses have fascinated some researchers and they were cataloged in the 2007 book, Tall Tales About the Mind and Brain. In Japan, the problem was termed kanashibar. In Newfoundland, people called it “the old hag.” In China, “ghost oppression” was the preferred nomenclature.
A study released earlier this year found that more than 90 percent of Mexican adolescents know the phrase “a dead body climbed on top of me” to describe the disorder. More than 25 percent of them had experienced it themselves.
You wake up, but you can’t move a muscle. Lying in bed, you’re totally conscious, and you realize that strange things are happening. There’s a crushing weight on your chest that’s humanoid. And it’s evil.
You’ve awakened into the dream world.
This is a standard description of the experience of a real medical condition: sleep paralysis. It’s a strange phenomenon that seems to happen to about half the population at least once.
People who experience it find themselves awake in the dream world for anywhere from a few seconds to 10 minutes, often experiencing hallucinations with dark undertones. Cultures from everywhere from Newfoundland to the Caribbean to Japan have come up with spiritual explanations for the phenomenon. Now, a new article in The Psychologist suggests sleep researchers are finally figuring out the neurological basis of the condition.
“This research strongly suggests that sleep paralysis is related to REM sleep, and in particular REM sleep that occurs at sleep onset,” write researchers Julia Santomauro and Christopher C. French of the Anomalistic Psychology Research Unit, Goldsmiths, at the University of London. “Shift work, jet lag, irregular sleep habits, overtiredness and sleep deprivation are all considered to be predisposing factors to sleep paralysis; this may be because such events disrupt the sleep–wake cycle, which can then cause [sleep-onset REM periods].”