Demons in the night

Cultural explanations for sleep paralysis focus on the supernatural, but researchers now know better.

Swiss artist Henry Fuseli’s 1781 oil painting “The Nightmare” appears to depict demonic hallucinations and feelings of suffocations associated with classic sleep paralysis experiences.

You wake up in the middle of the night. You open your eyes.

Something isn’t right.

You try to move, but you can’t. Your entire body is stuck to your bed. You feel as though the air is being pushed out of your lungs. You try to make a sound, but nothing comes out.

Then you see it.

Someone, or something, evil is standing over you. You try to scream, but no noise comes out. You try to move any part of your body — a finger even — but you can’t.

Moments feel like hours. Then, suddenly, it’s over.

This experience isn’t a dream. It’s a medical condition called sleep paralysis.

Sleep paralysis occurs when there’s a dysfunctional overlap between a stage of sleep called rapid eye movement, or REM, sleep and waking.

During REM sleep, people dream. Their breathing is shallow. The human body goes into REM atonia, a near-complete paralysis of the body. This paralysis stops people from acting out dreams.

When the waking state overlaps with REM sleep, people wake up unable to move due to REM atonia. They hallucinate malevolent entities or sounds and project them into their observable environment, likely due to the intense dream state of the brain during REM. The already-shallow breathing of REM sleep, combined with the feeling of panic from the paralysis and perceived bedroom intruders, creates a suffocating feeling. Some people even feel like they are floating.

The experience is short — usually only lasting between several seconds and two minutes — but distressing.

“Terror is not too strong a word to use here, because it seems as if nothing can be done,” wrote dream researcher Ryan Hurd in his book on the condition.

Sleep paralysis commonly occurs in people diagnosed with narcolepsy, a chronic sleep disorder that causes sudden and erratic attacks of drowsiness and sleep, according to the Mayo Clinic. Between 30 and 50 percent of people with narcolepsy also experience sleep paralysis.

The number of people without narcolepsy who experience isolated incidents, however, isn’t clear.

In 1999, the New York Times cited studies that claimed as much as 50 percent of the general population experiences sleep paralysis at least once. A 2011 review of sleep paralysis studies estimated that only 7.6 percent of the general population experiences sleep paralysis at least once in their lifetime.

That same review found that occurrences of sleep paralysis were much higher in students and psychiatric patients, around 30 percent of both groups experience it at least once.

Regardless of how many people wake up unable to move and struggling to breathe, the experience is nothing new and often mistaken for something supernatural.


In Herman Melville’s 1851 masterpiece Moby-Dick, the protagonist Ishmael suffers from a terrifying experience while sleeping.

“[A]nd slowly waking from it — half steeped in dreams — I opened my eyes and the before sunlit room was now wrapped in outer darkness. Instantly I felt a shock running through all my frame; nothing was to be seen and nothing was to be heard; but a supernatural hand seemed placed in mine. My arm hung over the counterpane, and the nameless, unimaginable silent form or phantom, to which the hand belonged, seemed closely seated by my bedside. For what seemed ages piled on ages, I lay there, frozen with the most awful fears, not daring to drag away my hand; yet ever thinking that if I could but stir it one single inch, the horrid spell would be broken.”

Though a work of fiction, the passage accurately describes what we now call sleep paralysis over two decades before neurologist Silas Weir Mitchell gave the first description in Western science in 1876.

Melville was far from the first person to recognize this condition before science categorized it. The word “nightmare” now refers to a distressing dream, but it originally referred to sleep paralysis. It’s derived from the Old English word noun “mara,” an evil goblin-like demon of European folklore that sits on the sleeper’s chest, causing them to struggle for breath.

Numerous cultures throughout history identified the experience and attributed it to an otherworldly entity, as folklorist and author Shelley R. Adler, Ph.D., notes in her book “Sleep Paralysis: Night-mares, Nocebos, and the Mind-Body Connection.”

In Turkey, a demonic entity called “karabasan,” which means “dark presser,” visits sleepers.

In Thailand, it’s called “phi um” or “ghost presser.”

The people of Newfoundland called sleep paralysis “Old Hag,” or “hagging,” or “hag-ridden.” The hag, a witch, would sit on sleepers’ chests in the night.

In Nigeria, the experience is referred to as having the Devil on your back.

The French are assaulted by a “cauchemar,” which comes from an old French word “caucher,” which refers to trampling or pressing.

Parts of the American South also attribute the experience to a hag or witch, calling it “witch-riding.”

In the book “Justice at Salem: Reexamining the Witch Trials,” William H. Cooke believes some self-professed victims of witch attacks may have experienced sleep paralysis.

Traditional treatments were usually religious in nature, but according to Dr. Fabio Pizza and Dr. Federica Provini, the best way to prevent sleep paralysis is to keep a healthy sleep schedule. Stress, irregular sleep schedules due to jet lag or working overnight and sleep deprivation may play a role in isolated incidents.

Treatments for isolated incidents are unnecessary; however, narcoleptics and those who suffer from frequent episodes are prescribed medications that suppress REM sleep, limiting the chance of an episode.

More concerning are the underlying reasons for sleep paralysis. While sporadic incidents of isolated sleep paralysis are difficult to predict and can affect anyone, the experience is more frequently associated with psychological conditions like panic disorder, post-traumatic stress disorder and anxiety.

Across cultures and throughout history, the experience has terrified individuals. Despite scientific understanding of the phenomenon, supernatural explanations aren’t a thing of the past.

“The cauchemar tradition is firmly planted in the present,” wrote folklorist Katherine Roberts in 1998 of Louisiana’s French-inspired nightmare hallucination. “Supernatural belief tradition, like all living traditions, remains vital to its practitioners.”

Al Cheyne, an associate professor of psychology at the University of Waterloo in Canada, and psychologist Kazuhiko Fukuda of Fukushima University in Japan told the New York Times they believe sleep paralysis could explain some claims of alien abduction.

“People will draw on the most plausible account in their repertoire to explain their experience. Trolls or witches no longer constitute plausible interpretations of these hallucinations,” Cheyne said in the Times. “The notion of aliens from outer space is more contemporary and somewhat more plausible to the modern mind.”

Even in the 21st century, nighttime intruders continue to paralyze and terrify.

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