Why Sleep Paralysis Demons Really Visit Us at Night

Sleep paralysis, a phenomenon as intriguing as it is frightening, captures the attention of both scientists and those who experience its eerie grip. Characterized by an inability to move or speak upon waking or falling asleep, this sleep disorder often comes with an unsettling, ominous presence.

Find out why it happens and how different cultures interpret these chilling sleep paralysis demons.

A "sleep paralysis demon" is a term often used to describe the terrifying hallucinations that some people experience during an episode of sleep paralysis. Sleep paralysis is a parasomnia (or sleep disorder) in which a person is fully awake and aware but cannot move or speak. It’s often accompanied by the perception of a sinister presence, vivid hallucinations, and a feeling of suffocation. Some people may even feel a sense of impending death.

Sleep paralysis is distinct from nightmares, but the two do share an etymology. The Old English word mare denoted an oppressive spirit (tormenting women in male form as the incubus, and men in female form as the succubus) that sat upon the chests of sleepers, hence the suffocation.

Researchers now believe the mare was inspired by sleep paralysis. The connection is clear in Henry Fuseli’s 18th-century painting, The Nightmare, where a goblinesque figure crouches atop a woman’s sprawled, inert body.

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Despite the physical and psychological toll of sleep paralysis, it remains a little-understood phenomenon. Its causes are unclear, but research has linked it to stress, sleep deprivation, excessive alcohol consumption, and even leg cramps. 

There’s also a strong correlation between sleep paralysis and other sleep disorders, like narcolepsy and obstructive sleep apnea, a condition characterized by interrupted breathing.

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Given its ghastly symptoms, it's understandable how our ancestors might attribute sleep paralysis to demonic forces. But sleep scientists have concluded that it’s actually a normal part of the sleep cycle that sometimes, abnormally, occurs in the semi-conscious moments before and after sleep. Some have referred to it as a mixed state of consciousness. A bout usually lasts seconds or minutes but can persist for longer.

The loss of muscle control from during sleep paralysis is called atonia, and it, too, has its rightful place in Rapid Eye Movement (REM) sleep, the phase in which most dreaming occurs. Brain signals reduce our muscle tone, inhibiting motion and preventing us from acting out our dreams. Only when atonia lingers into wakefulness do we become aware of the distressing inability to move.

One 2011 study found that about 8 percent of the general population experiences sleep paralysis, though the rates are much higher — around 30 percent — for both students and psychiatric patients. For some, isolated sleep paralysis instances happen rarely. But others suffer from recurrent sleep paralysis, which is typically associated with narcolepsy, or overpowering daytime drowsiness.

Even the malevolent, phantasmic images that plague these fitful sleepers have an earthly explanation. They’re called hypnagogic hallucinations when they occur just before sleep, and hypnopompic when they happen after waking. They can include not only visual but also auditory hallucinations, as well as bodily sensations, like floating or feeling pressure.

Read More: Why Is That Recurring Nightmare So Terrifying and Can It Be Treated?

People have various cultural interpretations and may think of mythical beings around the world for sleep paralysis. It’s often described as malevolent or supernatural entities that haunt or oppress people during their sleep. Here's a list explaining some common sleep paralysis demons from different cultures.

In Italy, it appears as a witch, a ghost or, sometimes, a horrid humanoid cat. They call it the Pandafeche; and a broom placed beside the bedroom door supposedly helps ward it off. 

In Newfoundland, it’s known as the Old Hag. Those experiencing the Old Hag syndrome report feeling as if an old woman is sitting on their chest or suffocating them during sleep. 

Inuit shamans, known as 'angakkuq', are considered to have the ability to communicate with spirits and traverse the spiritual world. A sleep demon in this context could be interpreted as a malevolent spirit or an entity sent by a shaman, a phenomenon known as a shamanistic attack. 

And in Brazil, the Pisadeira is described as “a crone with long fingernails who lurks on roofs at night and tramples the chest of those who sleep on a full stomach with belly up.”

In Chinese culture, sleep paralysis is often referred to as "ghost oppression" which attributes a spirit sitting on or pressing down on the individual.

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The framework through which different cultures interpret sleep paralysis may also alter the way their members experience the disorder. One study found that it is far more common in Egyptians than Danes, and that those Egyptians who attributed it to supernatural causes also feared it more. In an unfortunate cycle, if this anxiety causes people to avoid sleep, it can exacerbate the problem and spawn more episodes.

Read More: Are People More Prone to Supernatural Thinking if They Believe in the Afterlife?

By itself, sleep paralysis seems to be harmless. But when people eschew their beds to escape nighttime horrors, there can be a cascade of negative health consequences linked to sleep deprivation.

The treatments for sleep paralysis, like its causes, call for more investigation. In some cases, doctors may attempt to treat the associated conditions, like narcolepsy and sleep apnea. But in others, the simplest option may be to improve sleep habits and get at least seven hours of restful sleep each night. Poor sleep quality seems go hand in hand with sleep paralysis, so for many, healthy sleep is likely the best defense against that dreadful mare of the night.

Read More: Why Sleepwalking Still Mystifies Scientists

This article was originally published on Dec. 8, 2020 and has since been updated by the Discover staff.