Once, when I was 17, I woke up in the dark and couldn't move.
I could hear, at least. That's why I was awake to begin with: someone was banging on the front door in the middle of the night, insistent, sharp, angry.
I could see, too. My eyes were open to the ceiling above me. My head, though, was locked into position by some invisible vise. I tried to yell, to warn my parents about the angry intruder outside, and the irrevocable harm I was convinced he would do. I couldn't yell. The knocks got louder.
No matter how insistently I begged my body to jump out of bed and find a place to hide, it remained a slab. Something terrible was about to happen to me, to my family. The door was going to give way. The outsider was going to come in. I was going to face whatever— whoever?—came after completely immobilized and alone.
It was the most afraid I've ever been in my life. What I realized, looking back later, was that it still would have been even if it weren't for those knocks on the door, and my certainty that something awful would follow. My deepest fear came from the realization that my body, in that moment, had become completely dissociated from anything I recognized as myself. It was a car sinking to the bottom of a lake, my mind its captive passenger, waiting to drown.
I don't remember how long it lasted, but eventually it wore off. I quickly found out that the person on the porch was my older brother, home at an unexpected hour on an unexpected visit from college. It took me a few more years to figure out that the other part, the immobility, the sense of self reduced to flickering consciousness, even the deepness of the fear I felt, had a name. It was sleep paralysis.
What is sleep paralysis?
Sleep paralysis can be described as waking up and not being able to move nor speak. Dr. S.A. Kinnier Wilson coined the term in a 1928 edition of the medical journal Brain. His description then should feel familiar to anyone who has experienced sleep paralysis today: a man dreamed of a murderer, then carried that dream over to a conscious state. The patient in question "lay thus, flat on the floor, motionless but suffering acute mental stress."
"Sometimes she believed the devil lay upon her and held her down"
That's not to say that sleep paralysis is a relatively new human experience. A Dutch physician named Isbrand van Diemerbroeck published several case histories that accurately describe sleep paralysis in 1664, one of which, titled "Of the Night-Mare," may as well have been penned by Mary Shelley.
"In the night time, when she was composing her self to sleep, sometimes she believed the devil lay upon her and held her down, sometimes that she was choaked by a great dog or thief lying upon her breast, so that she could hardly speak or breath, and when she endeavored to throw off the burthen, she was not able to stir her member," van Diemerbroeck wrote, suggesting moderate exercise and plenty of juice as a possible remedy to the invisible nighttime demon attacks. [17th century sics implied throughout.]
Even that landmark medical documentation isn't remotely the first reported instance. Go back further still, and you'll find references to sleep paralysis in medieval Persia and Ancient Greece and even more ancient (400 BCE) China. There's probably a cave drawing somewhere that depicts a red-eyed saber-toothed tiger sitting atop a paralyzed Neanderthal's chest. Sleep paralysis is as ageless and as universal as fear itself.
Sleep Paralysis Causes
Sleep paralysis is not quite as simple as simply being afraid, though. It's a complex confluence of physiological and psychological occurrences that force you to experience your deepest nightmares with eyes wide open.
Take a normal night of sleep, assuming you still have those once in awhile. Your body cycles through five sleep stages, the last of which is REM, which you probably remember from your high school biology class as being your brain's lights-out, shut-it-down, dream-time state.
Which is great! Dreaming is wonderful, especially if you ever wondered what it might feel like to fly down Rodeo Drive with a soft serve twist cone in one hand and a chainsaw in the other. Dreaming, though, can also be dangerous, because your big dumb body doesn't necessarily know that your brain is just playing pretend. Given the opportunity, your body will act out those dreams, which can lead to a whole other terrifying condition called REM sleep behavior disorder (RBD).
You've heard of sleepwalking, which can technically be a type of RBD, depending on whether it occurs during the REM stage of sleep. Many RBD episodes are much more involved than just puttering down the hall, however. Think of it like this: juggling with tennis balls and juggling with flaming swords are both technically types of juggling, but you'd never confuse the two.
Comedian and storyteller Mike Birbiglia turned his experiences with RBD into a very entertaining show, book, and film called Sleepwalk with Me. Well, entertaining but also terrifying; at one point in his mid-20s, Birbiglia threw himself out of a closed, second-story La Quinta motel window. At the time, in his dream, he was trying to escape an incoming guided missile.
The reason more people don't experience RBD is that the brain also has a safety valve. "During dreaming… bursts of neural activity called PGO waves spread through the cortex, producing the imagery we experience during dreams," explained James Allan Cheyne, sleep paralysis expert and professor emeritus at the University of Waterloo. "Simultaneously, activation spreads down the spinal column causing spinal interneurons to suppress signals that normally would produce muscle movement."
Your body, in other words, paralyzes itself during REM sleep to keep you from throwing yourself down a stairwell when you dream about laying out for touchdown pass to win the state championship.
Sleep paralysis, then, is what happens when you wake up before that effect has had a chance to wear off. Your body has frozen to keep you from acting out your dreams. But also, haha, good joke, you're still dreaming.
"You have aspects of REM sleep that are going on when you have waking, conscious awareness," said Brian Sharpless, assistant professor of psychology at Washington State University and author of a recent book about sleep paralysis. "First, you're paralyzed, and second, you are having dreams, but unlike normal dreaming these two things are happening while you're awake and able to look around the room."
The bat demon was said to sodomize its victims. The response was violent.
Not just any dreams, though. Sharpless estimates that while a little less than a third of our normal dreams could be considered nightmares, 80 to 90 percent of dreams experienced during sleep paralysis qualify. "You can kind of imagine why," he said. "If you're lying on your back and can't move, that's scary enough. And if you're having hallucinations that are scary as well, that's a bad mix."
My own sleep paralysis, then, was fairly textbook. The banging on the door vaulted me into consciousness but not out of REM, leaving me frozen in a liminal hell of the mind, waiting for a bad man with an axe to bust down my door. Actually, I got off easy.
Types of Sleep Paralysis
As it turns out, sleep paralysis nightmares can be divided into three tidy categories: the Intruder, the Incubus, and Vestibular/Motor. (Two of these—the Intruder and the Incubus—would make for decent Paranormal Activity sequels.)
Cheyne cautions that these categories are broad, and the experiences the describe can vary greatly. On the other hand, he also is one of three authors of a landmark 1999 scientific paper, published in Consciousness and Cognition, that helped define them.
Vestibular and motor incidents—Cheyne calls it "Unusual Bodily Experiences" in his 1999 paper—are relatively harmless, potentially even enjoyable. "It's fancy term for feeling like your body is being moved without its volition," Sharpless explains. "You could feel like you're floating, or levitating, or your arm is being lifted." Not so bad, right? Your standard Sigourney-Weaver-in-Ghostbusters scenario.
The other two, Cheyne says, have no such upside potential.
"For Intruder experiences, the main sensation is the sensed presence—a feeling of something in the room," he recently explained over email. "That something may then also be seen, heard, or physically felt. It may move around the room, approach the bed, and sometimes climb onto the bed."
Scary! But remember, at this point you also can't move. As far as you know, you may never be able to move again, even if you somehow survive being horribly violated by the shadow monster in your periphery. Screaming would at least be cathartic, but you can't scream, and you can't breathe all that well, so all that's left is to wait.
I was fortunate in that my Intruder scenario involved an actual (friendly!) person. That gave quicker closure, presumably, than some hallucinatory demon-dog lurker might have. I was fortunate, also, that I didn't draw an Incubus instead:
"The Incubus experiences often continue this sequence by climbing on top of the 'sleeper,' Cheyne continues, "perhaps smothering, and even assaulting them physically and sexually." This is how your brain works. This is van Diemerbroeck's devil.
Popobawa: Raping Demon Attacks in Zanzibar in the 90s
Beginning in February of 1995, reports began to circulate throughout Zanzibar of a spirit that assaulted men and women in the dark of night. Its name was Popobawa, which means "winged bat," because that was the form it was said to take most often, though it was just as often invisible.
As social anthropologist Martin Walsh detailed in 2009, Popobawa attacks spread quickly throughout the country, jumping from person to person, house to house, and village to village, eventually constituting a full-blown paranormal pandemic.
The bat demon was said to sodomize its victims. The response was violent. At one point, residents of Zanzibar City murdered a suspected Popobawa who unsurprisingly turned out to be a human, one who had visited the capital in search of mental health treatment. The terrors, both spiritual and corporeal, continued. Then, three months after they began, the Popobawa incidents stopped.
An entire nation plagued by a sex-starved bat demon would laughable as a SyFy channel script. As reality, it seems impossible. That it led to mobs and murder, more so.
It happened, though. And again, to a lesser degree, in 2007 ("Sex attacks blamed on bat demon" read the restrained BBC headline that time). How?
"A typical [Popobawa] assault involved somebody waking up in the night to find themselves being attacked by an amorphous or shape-shifting intruder, which was most frequently described as 'pressing' or 'crushing' their chest and ribs, and of suffocating them until they had difficulty in breathing and passed out," Walsh wrote. "In general all of the victims experienced extreme terror, and were often frozen speechless when they were assaulted."
An intruder. An incubus. The inability to move. The loss of respiratory control. The Popobawa, Walsh concludes, was no demon. It was textbook sleep paralysis, at a massive scale.
Zanzibar's example is extreme, but far from isolated. Every culture has its bogeyman. Every century has ghost sightings. Everyone has heard things go bump in the night.
"We believe that sleep paralysis is a good, naturalistic explanation for a lot of paranormal beliefs," said Sharpless. "Alien abductions that occur at night; visits by ghosts and demons; more recently, shadow people. If you look at people's first-hand descriptions of these events, they map really well on to sleep paralysis."
"Different cultures have come up with unique names for sleep paralysis that are descriptive of various common experiences in how it manifests," explains Kevin Morton, who five years ago founded a site dedicated to better understanding sleep disorders as part of an undergraduate project at Stanford University. "In Japan it's been known as 'Kanashibari' (retaliating spirit), in Thailand 'Phi um' (enveloping ghost), or the 'Hauka'I po' (night marchers) in Hawaii."
In the same way that we might ascribe a happy coincidence to a guardian angel or God, we paint sleep paralysis with the brushstrokes of our deepest terrors.
Sleep paralysis being blamed on ghosts, spirits, and demons transcends cultures, but you can count on Japan to give it the perfect anime treatment.
How Many People Are Affected By Sleep Paralysis?
Estimates vary as to how many people will experience sleep paralysis at least once in their lifetime. Sharpless pegs it at 8 percent of the general population, with students (28 percent) and psychiatric patients (32 percent) even higher. Sharpless thinks that spike may be attributable to those groups having disrupted sleep patterns to begin with, making sleep paralysis more likely. Cheyne notes that incidence rates are higher still "in societies with an active tradition of haunting night spirits."
Despite the prevalence of sleep paralysis, especially among certain groups, there's been no large intervention trials to determine an effective treatment for it. In a 2014 paper, Dr. Sharpless and co-author Jessica Lynn Grom outlined a few preemptive methods (e.g., changing sleep positions and patterns), as well as techniques to help mitigate the impact mid-episode. Among the most effective of those? Simply trying to calm yourself down in the moment, if you can manage it. Focus on trying to move your extremities. Don't worry about the demon on your chest.
That's more easily accomplished if you're aware that you're experiencing sleep paralysis, or even of what sleep paralysis is. It's a condition that's been largely (apologies) in the dark, in part because it's not an easy thing to talk about. I didn't tell anyone about my experience for years, and even then it was only after I had found out what it was. Until then, I was too worried that it signaled something deeply wrong with my body or mind or both.
"Sleep paralysis has quite a large awareness bias associated with it," says Morton, whose site has received hundreds of submissions from people who have lived it, and a magnitude more visitors looking for answers. "It is such a crazy experience--waking up with your body paralyzed, often hallucinating frightening dream imagery, occasionally of a sexual nature--that those who experience it often don't talk about it with others, usually out of fear that they will be seen as crazy or possessed, or just otherwise stigmatized if they bring it up."
Morton is optimistic about the internet's power as a great normalizer; all it takes is a quick search of symptoms to find out that you're neither possessed nor insane. Sleep paralysis also seems to be having a larger cultural moment beyond the web, if a phenomenon as old as consciousness itself can be said to have moments.
That's a brief clip from The Nightmare, a documentary from Rodney Ascher, which brings brings to life people's real descriptions of sleep paralysis events. Ascher, who previously directed the critically lauded Room 237, pursued the topic after experiencing it himself. Devil in the Room , a short film released in 2014, takes a similar approach, while photographer Nicolas Bruno has a series of photographs depicting the horrors he has experienced in his years of sleep paralysis.
Most dreams stop when they want to, not when you tell them. A modicum of awareness, though, helps with what comes after. Even if you can't beat sleep paralysis, you can cope with its reverberations.
There's comfort in knowing that the demon on your chest actually resides in your mind. Or at least, that yours isn't the only mind with demons.
All in Your Head is a series that takes a scientific look at all things spooky and scary. Follow along here .