A series of strange symptoms known as sleep paralysis may be more common in college students and psychiatric patients, finds a new review study. But the odds of these weird occurrences happening in the general population are less than 8 percent.
Sleep paralysis occurs when you're falling asleep or waking up and you find your body paralyzed, says study author Brian Sharpless. It can be frightening because although your eyes can move, the rest of your body feels like it can't and you have some degree of awareness of this.
Along with this freaky body sensation, some people may also have hallucinations. "It's sort of like being in a dream while you're awake," explains Sharpless, a clinical assistant professor of psychology at Penn State University.
People in this dream-like state may describe seeing an intruder coming toward them in the bedroom or feeling the pressure of something being on top of their chest. They might feel as though their body is being levitated -- rising up, or say they see themselves outside of their body.
"Even though these hallucinations feel vivid, most of them are over in a few minutes," Sharpless points out.
Different cultures have described the mysteries of sleep paralysis in many colorful ways -- from demons visiting to evil spirits lurking to being abducted by aliens. But the medical explanation may be that it's part of REM (rapid eye movement) sleep that carries over into wakefulness.
To determine how common sleep paralysis is, psychologists analyzed data from 35 different studies. The research, published in the journal Sleep Medicine Reviews, found that roughly 20 percent of the more than 36,000 study participants had at least one episode.
Two groups had higher rates: More than 28 percent of college students and nearly 32 percent of psychiatric patients reported having these odd symptoms at least once.
Although researchers were surprised to find similar rates of sleep paralysis in students and psychiatric patients, both groups tend to have disrupted sleep, which can trigger an episode. Shift workers, jet-lagged travelers, or people with narcolepsy, a sleep disorder, may also experience these quirky -- and spooky -- symptoms because their bedtimes are also frequently interrupted.
In most cases, sleep paralysis is harmless although it can be a strange and scary event, admits Sharpless. But as his results suggest, it's not that uncommon. Even so, if it occurs regularly or is extremely upsetting, you may want to get checked out by a health professional.
Readers, if you've had an episode of sleep paralysis, leave a comment telling us what it was like. We might use your story in an upcoming Body Odd post.
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