Suddenly I’m awake. Something is on me. A shadow or a shape. Something nasty. I’m pinned to my bed and I can’t move a muscle. There are whispers, wicked whispers. I think I’m screaming but I make no sound. There’s a loud buzz, a whoosh, and I’m sucked out of myself, twisting, turning, then dragged. But through my ever-so-slightly-open eyes, I see my body is still motionless.

What I’m experiencing is literally a waking nightmare. It’s a state during which I’m awake but unable to move or cry for help, no matter what demons my mind conjures. The state has a name: Sleep Paralysis (SP), or more accurately in this case, Awareness During Sleep Paralysis (ASP). I’ve endured it hundreds of times before. And, as disturbing as it sounds, I’m far from the only one: People all over the world experience this terror. In fact, it’s as old as sleep itself.

Demonic imaginings aside, paralysis actually is an essential part of sleep. People dream when they’ve entered REM sleep, the near-conscious phase of slumber in which the eyes freely dart around but the rest of the body is immobile. There seems to be a clear utility to this: If our bodies could react to our nocturnal fantasies, who knows all the damage we’d do to ourselves and the people we sleep with.

But this sleep system isn’t foolproof. A combination of neurotransmitters is believed to be responsible for paralysis during REM sleep, acting together to switch off motoneuron activity. During normal sleep, the ability to move is switched back on before a sleeper wakes up. But for reasons that aren’t fully understood, sometimes things malfunction and the sleeper becomes conscious but remains frozen. When this occurs, the amygdala, the part of the brain that detects threats in the environment, triggers a primal fight-or-flight reaction. The brain screams to flee, but the body doesn’t react. The stuck person finds themselves in a blended state of consciousness: awake and aware of their surroundings, yet near enough to sleep to still experience dream-like hallucinations. The terror induced by being awake yet paralyzed most often drives the hallucinations towards the dark and disturbing.

According to James Cheyne, a psychologist at the University of Waterloo, up to 40 percent of people experience sleep paralysis once or twice in their lives. Usually they dismiss it as a terrifying—albeit extremely unusual—dream. Up to 6 percent of people (myself included) report multiple episodes over extended periods. In recent years, research by scholars such as Cheyne, who is one the world’s leading experts in sleep paralysis, and a flurry of media attention have increased public awareness of this bizarre state. But the scientific work also casts new light on a range of cultural beliefs across the globe. From ancient tales of demonic night visitors to contemporary reports of alien abductions, there’s a long history of terrifying tales that may be linked to sleep paralysis. These stories support a notion that while long-mysterious, the phenomenon is as common as sleep walking.

Prior to neurobiological explanations, which only have become possible in the past few decades, people had to rely on folklore to make sense of these nocturnal terrors. The accounts stretch back to antiquity, with remarkable consistency. Descriptions of sleep paralysis world-over share a sense of an intruder or presence in the room; painful feelings of being crushed, dragged, or touched; and visual, tactile, and aural hallucinations that range from laughing devils and demonic dogs to black shadowy figures and sex-crazed witches.

These descriptions have been especially bountiful in literature and art. In Herman Melville’s 1851 novel Moby Dick,  for example, Ishmael, the narrator, awakens to find himself unable to move and horrified to find that a “supernatural hand” appeared to be placed in his own:

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.

Another classic portrayal—and the illustration accompanies almost every article on sleep paralysis—is Henri Fuseli’s The Nightmare, a 1781 painting that depicts a woman lying on her back with a demon on her chest and a ghoulish mare lurking background. Pressure on the chest and the sense of being watched are common characteristics of sleep paralysis. Psychiatrist Jerome M. Schneck connected sleep paralysis to The Nightmare in 1969, and it is an interpretation that continues to be cited across research to this day.

Nocturnal visits from beasts are a particularly recurrent theme across cultures in apparent instances of sleep paralysis, and these animal manifestations are centuries old.  In numerous European countries a malevolent female horse was believed to prey on sleepers at night by pinning them down and riding upon their chests. These tales hide in plain sight in language that we continue to use, Cheyne explains: In France, she comes as the cauchemar (“mare-trampled”). In Germany, she haunts sleepers as the Nachtmahr (“night-mare”—which, yes, appears to be the origin of the English word). In Scandinavian countries, the word for nightmare literally translates as “mare-ride”; In Iceland, it’s martröð, in Denmark, mareridt , and in Norway, mareritt .

Tales of being choked and sat or ridden upon by other creatures of the night occur in many cultures. Newfoundland’s Old Hag (Ag Rog) is a witch who assaults sleepers and leaves them unable to cry out. This tradition is deeply engrained and fear of the Old Hag persists to this day. (The link between sleep paralysis and the Old Hag is discussed in depth in David J. Hufford’s 1989 book, The Terror that Comes in the Night.) In Germany, says Cheyne, sleepers of old may have awoken to find themselves subject to Hexendrücken (witch press) or Alpdruck (elf pressure). The Ancient Greeks told tales of pnigalion (the choker) and barychnas (the heavy breather).

Some mythologies appear to allude to the sexual sensations that can occur during sleep paralysis—an element of the experience that research still doesn’t well understand. There’s the Mesopotamian Incubus, who presses down on a female sleeper sometimes having intercourse with her, and Succubus, her male counterpart. And, in Surinam, terrified night-wakers might be paralyzed and sexually attacked by an apuku (gnome) or jorka (ancestor).

In certain countries, would-be sleepers are tormented by the dead or the unborn, who press on or pull at the body. In St. Lucia, an attack of kokma occurs when souls of dead children crawl on a person’s chest and try to choke them. In Thailand, a person can be phi um (ghost covered) or phi kau (ghost possessed). In Ethiopia, a Zar (ghost) might try to smoother someone in the night. While in Inuit cultures, a person can be subject to aqtuqsinniq or uqumangirniq when a malevolent spirit tries to possess a night-paralysed body.

Japanese folk tales feature accounts of kanashibari (Japanese for “bound by metal”), a magical power belonging to the Buddhist deity Fudoh Myo-oh and wandering monks that allowed them to immobilize animals and people. The psychologist Kazuhiko Fukuda at Edogawa University in Japan has studied the connection between kanashibari and sleep paralysis, and explained to me that in popular TV shows from the 1950s onwards, the Japanese media started to use the word kanashibari to talk about the phenomenon.

“The word kanashibari is now very well-known for meaning this phenomenon.  Almost all Japanese, almost 100%, know the word for this usage.  Some believe the phenomenon is caused by spiritual beings, some not,” he wrote in an email.

TV shows may play a role in other cultural and contemporary interpretations of sleep paralysis. Several scholars, including Christopher French, a psychologist at Goldsmith’s University, in the United Kingdom, have argued that accounts of UFO abduction and alien encounters may in fact be incidents of sleep paralysis. These reports are most widespread in the U.S., where alien-themed shows and movies have perhaps fueled the collective imagination. Sleep-paralysis characteristics such as pressure and pain, the presence of an intruder, sexual encounters, disassociation from the body, and strange lights and sounds gel easily with cinematic portrayals of alien visitation.

French has also studied the link between a person’s level of belief in the supernatural and their interpretation of sleep paralysis. He argues that the relationship between pre-existing belief systems and the content of the hallucinations is one of mutual influence. “It seems likely that the core experience has itself played a role in the development of belief systems relating to the spirit world in many cultures and that those very belief systems, once elaborated upon, are then capable of influencing the hallucinatory content of sleep paralysis episodes in subsequent generations,” French wrote in The Guardian in 2009.

I have regularly experienced sleep paralysis for as long as I can remember. While I accept and am reassured by the scientific explanations, I understand why supernatural interpretations persist. Imagine waking up from a nightmare that doesn’t stop. It’s hard to convince yourself that what you’re seeing isn’t real when you’re awake and the devil or witch or horse is right in front of you.

But that’s not to say the experience must always be a dreadful one. In fact, contrary to sleep paralysis’s historical reign of terror over innocent sleepers, there may be an unexplored joyful side to the phenomenon. In Wrestling With Ghosts: A Personal and Scientific Account of Sleep Paralysis, Jorge Conesa Sevilla, a psychologist at Northland College, outlines techniques for talking oneself out of the usual panic while still frozen, so that the fear-driven hallucinations disappear. The result, Sevilla claims, is the ability to explore this bizarre level of consciousness without anxiety. The technique is meant to offer a doorway to lucid dreaming, where the calmed person goes back to sleep but retains waking levels of awareness.

Nowadays, when I wake into this paralyzed state, I try to ride the fear out. I let myself return to sleep but attempt to stay lucid. It’s a slippery state of consciousness that I achieve sometimes through luck and sometimes through intention, or fail to achieve altogether. But, when I succeed, I can consciously influence the content of my dreams. I fly across fantastical landscapes, interact with characters I place into my dreams, and play with the strange bodily sensations that this bound “dream state with consciousness” allows.

The trade-off for the terror, perhaps, has always been the key to a world that few people have access to. Arguably, as public awareness increases of sleep paralysis, Sevilla’s approach could prove to be one of the most effective “cures” for those who continue to be stuck in the horror.