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Formal Source: The Neuroscience of Sleep Paralysis

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Formal Source: The Neuroscience of Sleep Paralysis

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People who experience hallucinations during their sleep paralysis have higher trauma and anxiety symptoms. Both sleep paralysis and lucid dreaming are consciousness states that lie between REM sleep and wakefulness; the former is dreaming while awake, and the latter, being awake while dreaming. A more radical approach to overcome the fear of sleep paralysis is by literally turning your back on the terrifying monster, by sliding into a lucid dream (a dream where you are aware that you are dreaming).

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Sleep paralysis is a condition in which a person awakens from sleep but is temporarily paralyzed, unable to move or speak. The phenomenon, in fact, is not uncommon. Around 20 to 40 percent of people experience sleep paralysis at least once in their life.

Though the episodes of sleep paralysis are brief, lasting a few seconds to minutes, they are rich with mystery and potential insight into the nature of the human brain. How does sleep paralysis happen, and why does it accompany the strangest hallucinations?

Origins of sleep paralysis

Sleep paralysis often occurs when we take a nap during the day, when we are jet lagged, or in any way, sleep deprived. It happens when we wake up while we are still in a stage of sleep, called rapid eye movement, or REM, during which most vivid dreams occur. During REM, a part of the front brain called the dorsolateral prefrontal cortex, central to our ability to plan and think logically, turns off. This explains why our dreams during REM seem so real, and why the fabric of reality appears so out of control-with warped landscapes and abruptly changing times, places and people (the Hollywood blockbuster "Inception" brilliantly captures the surreal flavor of dreams).

Occasionally, the vivid, and sometimes threatening dreaming of REM can "spill over" into waking consciousness. The result can best be described as a dream, or worse yet, a nightmare, coming alive before your eyes.

To prevent us from acting out such intensely "real" dreams during REM, and potentially hurt ourselves, our brain has a brilliant solution: it turns our body temporarily paralyzed.

REM is also the stage that most resembles wakefulness. Our blood pressure, heartbeat and breathing quicken and even brain waves speed up, becoming virtually indistinguishable from wakefulness.

Sometimes, however, we actually do wake up while still in REM sleep. In a sense, we have a "switch" in the brain that tilts us between REM and wakefulness. And all it takes is a few neurochemicals to leave us stuck in this borderline state between parallel "realities"-sleep and wakefulness.

As if being paralyzed and unable to speak when waking up isn't chilling enough, occasionally, the vivid, and sometimes threatening dreaming of REM can "spill over" into waking consciousness. This state-in medical jargon referred to as "sleep paralysis accompanied by hypnopompic hallucinations"-can best be described as a dream, or worse yet, a nightmare, coming alive before your eyes.

Becoming a ghost

Sleep paralysis can sometimes cause eerie sensations of floating outside one's body or looking down upon oneself from the bedroom ceiling. In certain cultures, such out-of-body experiences are attributed to the "soul"- as if in a type of "astral travel," the spiritual self projects itself into an alternative realm of existence.

But out-of-body experiences originate in the brain. In fact, they can reliably be produced in the laboratory. We simply have to disrupt the activity of a brain region called the temporoparietal junction. This region helps us build a "body image" in the parietal lobes (the top-middle part of the brain), or a type of neural representation of the self, based on the inputs it receives from the senses. The temporoparietal junction, which is also critical for our ability to distinguish between "self" and "other," is normally turned off during REM sleep. This is why there is a loosening of the sense of self when we dream: we sometimes see ourselves from a third-person perspective, and other times the self occupies another person's body.

The confusing signals received by the brain can influence how the brain builds our sense of self.

We've suggested that disturbances in the temporoparietal junction can occur during sleep paralysis. When we realize we are paralyzed, the motor cortex in the brain immediately sends signals to the rest of the body to move and to overcome the paralysis. It also sends additional signals (sort of like "CCing" when emailing) to the parietal lobes. Normally, there is feedback from the limbs telling the brain how to build our body image, but not during sleep paralysis.

The confusing signals received by the brain can influence how the brain builds our sense of self, and the result is all kinds of bizarre bodily hallucinations, such as out-of-body experiences, seeing one's limbs or entire body rotate in the air like a tornado or sink deep into the bed as if drowning in quicksand.

Seeing a ghost

Perhaps more distressing than becoming a ghost, is seeing one. Sleep paralysis is arguably most infamous for the sinister shadowy "bedroom intruder" that sometimes attacks the sleeper. The "creature" is usually lurking in the distant dark, slowly approaching in on its victim. From here, all kinds of ominous things happen, as countless as the imagination can stretch. Commonly, the intruder chokes and suffocates the person by crushing his chest or pressing on his neck. And occasionally, the creature brutally rapes the paralyzed sleeper. The figure often appears simply as a dark shadow, similar to the human size and shape. But it can also appear as a scary demonic face, and include detailed features, for example, animal characteristics like sharp teeth and cat-eyes.

This figure goes by different names around the world. My colleague Devon Hinton of Harvard Medical School and I found that in Egypt, the creature is thought to be a Jinn - a spirit-like entity (or evil genie) that may hunt down, terrorize and even kill its victims. In another study we've discovered that among some Italians it is believed to be a malevolent witch or a terrifying giant cat, known locally as the Pandafeche. And in Turkey, we've recently discovered that the phenomenon is known as a dangerous Karabasan attack (supernatural creatures that attack the sleeper). Some space alien abduction cases also fit the sleep paralysis scenario: the person is laying in his bed paralyzed; suddenly the alien appears and begins to experiment on the sleeper's sexual organs, collecting eggs and semen.

UC San Diego neuroscientist VS Ramachandran and I proposed a neurological explanation for why we see this shadowy creature during sleep paralysis.

The idea was sparked by research showing that people who are born with a missing arm may experience phantom limbs, meaning that they feel the presence of missing limbs. This led to the idea that there might be a "hard-wired" template or map of a person's body surface in the right parietal lobe of the brain. So when a person born with no arm is experiencing a phantom arm, he is really feeling the presence of the "arm" that is part of his internal body map. This map would be connected to emotional and visual centers in the brain, causing us to be attracted to body shapes similar to our own. In other words, it may be why we as humans are innately attracted to other humans, and not to, say, pigs (at least most of us!).

More clues about such a hard-wired body map come from a rare disorder called apotemnophilia, in which a person has a desire to have a limb amputated and is attracted to people with missing limbs.

Ramachandran and I suggested that a disturbance in the processing of "self" and "other" at the temporoparietal junction results in a hallucinated projection of one's own body map; the mind literally casts a shadow, just like the body does. As the barrier between self and other dissolves, the person mistakes his own "shadow" (or body template) for a separate entity.

(The temporoparietal junction, Wikicommons)
Compare this to an out-of-body experience: here your sense of self is shifted and you identify with your "ghostly self", not your "bodily self". When you see a "ghost", on the other hand, your vantage point doesn't get shifted and you identify with your "bodily self", instead of your "ghostly self." And with the "threat detection system" of the brain on high alert (also known as "threat hypervigilance"), we are even more likely to interpret the human-like shadow as an evil, other entity.

Moreover, our brain regards it as highly improbable that chest pressure, sensations of suffocation, rapid breathing (which are caused by REM physiology) and on top of everything, seeing a human-like shadow, occur by random chance. When REM dreaming becomes activated as well, the shadowy-figure can take on all kinds of sophisticated shapes and dimensions, and the entire plot thickens. At this point, memory and the narrative abilities of other brain regions, play a role in the evolving hallucination.

Our neurological explanation for the shadowy-figure fits well with previous observations. It has been shown that occasionally, when the temporoparietal junction is disrupted using an electrical current, instead of having an out-of-body experience, the person senses a presence of a shadowy-figure. This figure is perceived to stand behind the person and to mimic his posture; even though the person is aware that the postural features of the shadowy-figure are similar to his, he still regards it as a separate person. Based on this, the scientists who conducted the study concluded that they had created a "ghost-like" double.

Building on this neuroscientific account for why people see ghosts during sleep paralysis, Ramachandran and I recently theorized how a specific type of neurons, known as mirror neurons, may play a crucial role in triggering these hallucinations during sleep paralysis.

The role of fear

In the 1986 Stephen King horror Novel "It," the clown-like killer exploits the fears of its victims to hunt down its prey - young children who fear monsters. Although fictional, literature is sometimes closer to science than one would think. Our own research suggests that one's beliefs about sleep paralysis can profoundly shape the experience.

In one study, we found that in Denmark, people regard their sleep paralysis as something trivial caused by the brain. In sharp contrast, we found Egyptians often hold very specific cultural and supernatural beliefs about theirs. In another study, Devon Hinton and I discovered that Egyptians experiencing sleep paralysis, not only fear it much more than Danes do - to the extent that many fear dying from it - but they also have longer episodes, and on average experience sleep paralysis three times more often.

These findings strongly indicate that for Egyptians, beliefs have radically transformed the experience - a form of mind-body interaction - causing not only psychological fear, but also conditioned physiological fear of sleep paralysis. When they go to bed, they fear the creature might attack them, which, ironically, will activate fear centers of the brain (such as the amygdala), making them more likely to wake up during REM and have sleep paralysis. And once they have sleep paralysis, they interpret it in light of their cultural beliefs, thinking, "I am being attacked by an evil spirit," which makes them even more terrified. With escalating fear and arousal, they are more likely to try to move during the paralysis, causing body image disturbances and generating more intense hallucinations.

And it doesn't end there. Now they notice that they are experiencing sleep paralysis more often, that episodes are longer and more horrifying, and become more convinced that they are targeted, perhaps even possessed, by a supernatural creature. They become even more afraid, and this vicious cycle - which I've called the Panic-Hallucination Model - continues to feed on itself.

People who experience hallucinations during their sleep paralysis have higher trauma and anxiety symptoms.

It is still unclear whether the fear generated by sleep paralysis can be pathological. But in one study conducted in Egypt, we found that experiencers of sleep paralysis have higher symptoms of trauma and anxiety compared to those who have never experienced it. Intriguingly, we also found that those who experience hallucinations during their sleep paralysis have higher trauma and anxiety symptoms. These findings point to the possibility that sleep paralysis, if accompanied by certain beliefs, might be a traumatizing experience. This is also consistent with the findings of my colleague, Harvard University professor, Richard McNally, that sleep paralysis interpreted as alien abduction can elicit physiological fear comparable to patients with post-traumatic stress disorder.

A gateway to lucid dreaming

In the 1984 horror movie "A Nightmare on Elm Street, " the ghost Freddy Krueger ferociously terrorizes and kills young teenagers during their nightmares. But the protagonist Nancy is finally able to make Krueger vanish from her nightmares; she follows the advice of her friend Glen (played by a young Johnny Depp) who insists that if you turn your back on the monster, you "take away its energy and it disappears."

Indeed, dispelling the fear surrounding sleep paralysis is an important means to help people cope with their experience; and, crucially, prevent escalating fear cycles that can lead to worse and more frequent episodes. One way to do this is to disseminate scientific knowledge about the experience. This often works. People are genuinely relieved to hear that they aren't "crazy," that they aren't the only one experiencing it, and that the phenomenon seems to originate in the brain.

Both sleep paralysis and lucid dreaming are consciousness states that lie between REM sleep and wakefulness; the former is dreaming while awake, and the latter, being awake while dreaming.

A more radical approach to overcome the fear of sleep paralysis is by literally turning your back on the terrifying monster, by sliding into a lucid dream (a dream where you are aware that you are dreaming). It is not surprising that sleep paralysis can be a gateway to lucid dreaming. Both sleep paralysis and lucid dreaming are consciousness states that lie between REM and wakefulness; the former is dreaming while awake, and the latter, being awake while dreaming.

Neural circuitry associated with wakefulness, such as the dorsolateral prefrontal cortex that helps us organize our logical thoughts, is turned off during REM. But it is more likely to become activated during sleep paralysis, and if it does, we enter into a type of hybrid consciousness that combines the surreal dreams and the rationality of wakefulness. And so, we become aware that we are dreaming - like a great Michelangelo we can create our own fantasy worlds composed of colorful landscapes and creatures of all kinds conjured by our minds.

I was once able to slide into a lucid dream during my own sleep paralysis. Lucky for me, no terrifying intruders were present. When I became aware that my dreaming self was walking around in my bedroom, it occurred to me to do an experiment. I found a piece of scrap paper on the floor and put it in my pocket. I thought to myself, if it's still there upon awakening, I would have to reconsider some of my own scientific theories about the role of the brain in favor of more uncanny explanations.

My pocket was empty when I woke up.

On a different occasion, I wanted to test whether by deliberately trying to move during the paralysis (causing disturbances to my body image) and imagining that a sinister creature was present in my bedroom (activating dream imagery), I could create my own hallucinated Frankenstein monster. I wasn't able to complete the experiment out of sheer horror, but I still joke with my colleagues telling them that we're among a select group of people who can say we're working while sleeping.

Treatments for sleep paralysis

Based on my scientific work on sleep paralysis around the world and our proposed neurological explanation for why people hallucinate ghosts during the episode, I thought to myself, how do I create a simple, yet effective therapy for sufferers. Meditation-Relaxation Therapy or MR therapy for sleep paralysis was recently designed as a direct treatment for sleep paralysis. The treatment which includes techniques of cognitive reappraisals and emotional distancing, meditation and muscle-relaxation, aims to minimize current attacks and decrease frequency, severity and duration of future ones.

As we are beginning to probe this fascinating condition, and unlock its neural basis, the mystery is no less. Here is a single phenomenon that can make us see and become ghosts, have encounters with space aliens from distant galaxies, and plunge into far and exotic lands of lucid dreaming, where we are the sculptors of our own realities, all the while laying silently in our beds. It shows us firsthand how the feeling of a sense of self, as a unified entity separate from others, arises in the brain, and how vulnerable this feeling is to disruption.

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The Neuroscience of Sleep Paralysis - Thrive Global

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Sleep paralysis is a condition in which a person awakens from sleep but is temporarily paralyzed, unable to move or speak. The phenomenon, in fact, is not uncommon. Around 20 to 40 percent of people experience sleep paralysis at least once in their life.

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I interviewed one of my friends on November 9th 2019, who has experienced sleep paralysis for 7 years now. This allowed me to get a more personal and detail version of a hallucination.

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Having nightmares is the way the brain detoxifies and discards old fearful memories. Research subjects were told to keep dream journals at home and are periodically awoken out of rapid eye movement, or REM, sleep — the stage most often associated with dreaming. About three-quarters of the emotions were described to be negative. Nightmares offer clues into the larger mystery of why we dream in the first place, how our dreaming and waking lives may intersect and cross-infect each other.

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Moreover, said Robert Stickgold, a sleep researcher at the Harvard Medical School, we are ridiculously industrious dreamers, spending 60 to 70 percent of somnolence dreaming or in a dreamlike state called sleep mentation, which works out to three hours nightly spent in a state of anxiety or frustration as we show up late for tests or walk barefoot over broken glass because our shoes have melted.

Even bona fide nightmares are more common than most of us realize. Ask people to recall spontaneously how many nightmares they had in the last year, and they might say one or two, said Mark Blagrove, a dream researcher at the University of Wales in Swansea. Ask them to keep a dream diary, and they will report nightmares once or twice a month.

Survey and diary studies have shown that nightmare frequency varies by age and sex. Preschoolers are relatively immune to the bogeyman fetish, but not so their elder siblings. Roughly 25 percent of children ages 5 to 12 report being awakened by bad dreams at least once a week.

Nightmare rates climb through adolescence, peak in young adulthood, and then, like so much else in life, begin to drop. The average 55-year-old has one-third the number of nightmares as the average 25-year-old. At nearly every age, girls and women report having significantly more nightmares than do boys and men, a fact that some researchers say may be related to women's comparatively higher rates of anxiety and mood disorders.

Nightmare content also shifts over time and across cultures. A young man in 21st-century America might not mind the occasional bawdy dream, but for St. Augustine, the fourth-century Christian philosopher, "sexual dreams were nightmares," said Kelly Bulkeley, a dream researcher and visiting scholar at the Graduate Theological Union in Berkeley, Calif. "He considered them threats to his faith."

Cultural specifics can also tweak universal themes. Dr. Bulkeley and his colleagues have found that nightmares about falling through the air are common among women in Arab nations, perhaps for metaphorical reasons. "There's such a premium in these countries on women remaining chaste, and the dangers of becoming a 'fallen woman' are so intense," he said, "that the naturally high baseline of falling dreams is amped up even more."

Using brain imaging devices that are noisy and uncomfortable and less than conducive to a good night's sleep, scientists have nonetheless begun identifying which regions of the brain are active during sleep and which are largely off-line. The brain proceeds through four stages of sleep at night, each characterized by its own pattern of brainwaves and neurochemical activity. REM sleep, when the eyes are flitting behind closed lids, is rightly renowned as the dreaming stage, with at least 90 percent of it spent dreaming. But dreams occur in parts of non-REM sleep, as well.

When slipping into REM sleep, Dr. Levin said, "the whole brain changes." "Neurochemically, it's like the Fourth of July," as cortical precincts shift colors in scanning images to indicate arousal or quiescence, he said, adding, "The limbic system becomes incredibly active, much more so than when you're awake, which is why you're emotionally on edge in dreams."

Blazing with particularly patriotic fervor in the limbic system are the amygdala and anterior cingulate cortex, constituting what Steven H. Woodward, a psychologist at the V.A. hospital in Menlo Park, Calif., terms the brain's "axis of fear." At the same time, the prefrontal cortex, seat of rational thought and critical reasoning, is on lunch break, Dr. Levin said, "which is why you can have a dream where something has 4 heads and 12 legs, and you think, 'No problem, what's next?'"

Also relatively tranquilized is the primary visual cortex, recipient of visual signals from the outside world. The secondary visual cortex, however, which helps process and interpret those signals, remains alert. It is here that the fabulous imagery of dreams probably arises, said Tore Nielsen of the University of Montreal, as the secondary visual cortex strives to decipher the signals ricocheting through it, many of them internally generated, and to splice them into some approximation of a coherent whole.

Other sensory and motor systems remain active in REM, including those that would normally control the arms and legs, which is why motion figures prominently in many dreams. But if you often feel frustrated, as though you can never get to where you're going, well, you can't.

As it happens, one vigilant player in dreaming is a small region of the brainstem that paralyzes most of the body, preventing you from physically acting out your dream. People with neurogenerative diseases that disable this brainstem disabler can end up injuring themselves during extreme dream-driven actions. Most cases of sleepwalking occur in non-REM sleep, when the body is not paralyzed.

With so much of the sleeping body and brain apparently colluding to allow us to wander safely through an ominous dreamscape of extravagant characters, most sleep scientists are convinced that dreaming serves an essential, possibly evolutionarily adaptive, purpose.

In a recent paper in Psychological Bulletin, Dr. Nielsen and Dr. Levin proposed that dreaming served to create what they call "fear extinction memories," the brain's way of scrambling, detoxifying and finally discarding old fearful memories, the better to move on and make synaptic space for any novel threats that may show up at the door. "The brain learns quickly what to be afraid of," Dr. Nielsen said. "But if there isn't a check on the process, we'd fear things in adulthood we feared in childhood."

Ordinary bad dreams rarely recapitulate unpleasant events from real life but instead cannibalize them for props and spare parts, and through that reinvention, Dr. Nielsen explained, the fears are defanged. "A bad dream that doesn't lead to awakening is successful in dealing with intense emotion," he said. "It's disturbing, but there is some kind of resolution to the extent we don't wake up."

By this scenario, nightmares, in allowing you to escape prematurely, represent a failure of the "fear extinction" system. "Bad dreams are functional, nightmares dysfunctional," he said.

If you feel yourself falling, spread your arms out and learn how to fly.

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Moreover, said Robert Stickgold, a sleep researcher at the Harvard Medical School, we are ridiculously industrious dreamers, spending 60 to 70 percent of somnolence dreaming or in a dreamlike state called sleep mentation, which works out to three hours nightly spent in a state of anxiety or frustration as we show up late for tests or walk barefoot over broken glass because our shoes have melted.

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Chemical imbalances can change the pattern of signals. Having a slightly different pattern, can lead to one being trapped inside a reality in which strange and impossible things can happen. "Reality is a narrative played out inside the seal auditorium of the cranium."

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This is a very subjective question. Meaning it always depends on who you're asking. Because none of this has yet to be "proven" people will argue forThis is a very subjective question. Meaning it always depends on who you're asking. Because none of this has yet to be "proven" people will argue for whoever's research and theories they agree with. I can give you some of my own personal (and I try really hard to be objective and steer clear of opinions, but that will always have a role so that's just my warning label of sorts, ha) but because this is such a big topic today it'd help if you were more specific... do you mean subconscious mind just basically like how we make decisions, fears, etc or do you want to go deeper meaning the abnormal subconscious mind and/or subconscious mind of trauma, etc. there are so many good out there. If you want recs let me know, but another good way to find is to do a bit of research online and/or going to a book store and looking at several books that deal with your specific questions... I hope this helps! ...more (less)

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This is a very subjective question. Meaning it always depends on who you're asking. Because none of this has yet to be "proven" people will argue forThis is a very subjective question. Meaning it always depends on who you're asking. Because none of this has yet to be "proven" people will argue for whoever's research and theories they agree with.

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Formal Source: Examples of hallucinations 

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Formal Source: Examples of hallucinations 

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Several studies have also found links between social anxiety or panic disorder and sleep paralysis. Research shows that people in countries as diverse as China, East Africa, Mexico, Newfoundland, and the United States have long believed that paralysis is caused by demons, witches, or other supernatural creatures sitting on their chests and sometimes trying to have sex with them. In fact, some researchers believe sleep paralysis is what's really going on with stories of alien abductions.

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You wake up in the middle of the night, convinced that an evil figure is lying in wait. You attempt to move, but your body just will not budge. You try to scream, but nothing comes out. The monster draws closer. It may sound like a horror movie scene, but this is the real deal - you're experiencing sleep paralysis.

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Sleep paralysis is like a waking nightmare, and the underlying causes for this condition remain unclear.

This terrifying and mysterious sleep disorder, or parasomnia, has been experienced by people possibly since the dawn of humankind.

And, it may have given rise to numerous ghost stories and mysterious accounts involving "things that go bump in the night."

This most unsettling experience was first clearly documented in a medical treatise in the 17th century, by Dutch physician Isbrand Van Diembroeck, who wrote about the case of a woman "50 years of age, in good plight [health], strong," yet who complained of mysterious experiences at night.

"[W]hen she was composing her self to sleep," explains Van Diembroeck, "sometimes she believed the devil lay upon her and held her down, sometimes that she was [choked] by a great dog or thief lying upon her breast, so that she could hardly speak or [breathe], and when she endeavored to throw off the [burden], she was not able to stir her members."

What the woman in Van Dimbroeck's account likely experienced was a condition that has come to be known as " sleep paralysis."

Researchers define it as "a common, generally benign, parasomnia characterized by brief episodes of inability to move or speak combined with waking consciousness."

Sleep paralysis and hallucinations

The reason why sleep paralysis is so scary is not just because you will suddenly become alert but realize that you are, in fact, unable to move a muscle or utter a sound, but also because this experience is often - as in the case above - accompanied by terrifying hallucinations.

These, as specialized literature has now ascertained, typically fall into three distinct categories:

1. a sensed presence, or intruder hallucinations, in which the person feels the presence of an evil, threatening individual

2. incubus hallucinations, in which the person might feel someone or something pressing down uncomfortably, even painfully, on their chest or abdomen, or trying to choke them

3. vestibular-motor hallucinations, during which the individual thinks that they are floating, flying, or moving - these may also sometimes include out-of-body experiences, in which a person thinks that their spirit or mind has left their body and is moving and observing events from above

Among the types of dreamlike hallucinations listed above, the first type - a sensed presence - is one of the most commonly experienced by people with sleep paralysis.
As for the time of sleep at which sleep paralysis - with or without hallucinations - normally takes place, again, there is no single answer.

According to a study that was published in the Journal of Sleep Research, sleep paralysis typically happens soon after falling asleep (or hypnagogic episodes), at some point during the course of sleep (or hypnomesic episodes), or a little before the person's usual time of awakening (or hypnopompic episodes).

The authors of that study note that the most common instances of sleep paralysis are hypnomesic, and that they usually take place after 1-3 hours from falling asleep.

'A strange, shadowy man'

In fact, these visions and sensations can seem so realistic to many people that they may think that they are having a paranormal experience, or even being subjected to strange tests and rituals.

The most common hallucination linked to sleep paralysis is the 'sensed presence' of a sinister figure.

"Witness accounts" of such hallucinations can be truly unsettling, and a number of long-time experients - such as Louid Proud in his book Dark Intrusions - have offered detailed accounts of years of uncanny nightly encounters.

One person who told me about his nightmarish hallucinations said he felt as if "someone knelt on [his] chest so that it [felt] as if [he was] being choked out."

Another person spoke of a night-time assailant that takes pleasure in tormenting her in myriad ways.

"When [sleep paralysis] strikes, I get both visual and auditory hallucinations, which most often involve a strange, shadowy man coming up my stairs and into my bedroom. Occasionally, he'll prod or tickle me."

Often, she told me, this sinister figure even "co-opts" her partner in his mischief.

"Sometimes," she says, "I'll even hallucinate my partner lying next to me and laughing maliciously at me, or siding with the shadowy figure in annoying me. This is very frustrating, since all I want him to do is help me!"

Given the intensity of these hallucinatory experiences, it may come as no surprise that researchers have repeatedly argued that hallucinations linked with sleep paralysis can be held responsible for many reports of magical events, sightings of ghouls and demons, and alien abductions.

Some happy exceptions

Although usually people with sleep paralysis report experiencing terrifying hallucinations, a happy few actually point to a state of bliss that makes them look forward to these episodes.

A study that was conducted by James Allan Cheyne, from the University of Waterloo in Ontario, Canada, suggests that the people who most often describe experiencing positive feelings and sensations during an episode of sleep paralysis are those who are prone to vestibular-motor hallucinations.

"These hallucinations were found to involve feelings of floating and [out-of-body experiences], which are associated with feelings of bliss rather than fear."

James Allan Cheyne

"In contrast to the other-oriented nature of the Intruder and Incubus hallucinations," he adds, "these experiences are very much focused on the experient's own person."

Sometimes, Cheyne continues, feelings of bliss during sleep paralysis are derived from pleasant erotic sensations that arise from vestibular-motor hallucinations.

What is the underlying mechanism?

So, what happens in the body during an episode of sleep paralysis? Essentially, during the dream phase of sleep - known as the rapid eye movement ( REM) phase - our skeletal muscles are paralyzed.

The reasons behind this are not fully understood, though researchers have been making progress in uncovering the mechanisms attached to this process.

One popular theory posits that this temporary state of paralysis is meant to prevent us from hurting ourselves, perhaps in automatic response to some violent dream.
During sleep paralysis, paradoxically, our brains - or parts of our brains - become awake and conscious, but the rest of the body is still immobilized.
At the same time, during sleep paralysis, many people experience dream visions and sensations as though they were real - hence the hallucinations - and the fact that they are, in fact, partly awake and conscious blurs the line between reality and dreams.

Who is at risk of sleep paralysis?

Sleep paralysis is more common than we may think. A declares that it is "surprisingly common," but that "determining accurate prevalence rates is complicated" because researchers and study participants alike have different understandings of what counts as sleep paralysis.

Although a fair amount of research has been conducted in this respect, it remais unclear as to who is most at risk of sleep paralysis.

A recent review of the available data, however, suggests that 7.6 percent of the population have experienced at least one episode throughout their lives.

That said, the numbers may be even higher.

What causes sleep paralysis, and what the main risks are for experiencing such an episode, remain largely mysterious.
Sleep paralysis is a common symptom of the neurological disorder "narcolepsy," which is characterized by uncontrollable sleepiness throughout the waking day.
But many people who experience sleep paralysis do so independently of neurological conditions. And, to distinguish between narcolepsy-related episodes and independently occurring sleep paralysis, specialists usually refer to the latter as "isolated sleep paralysis."

Recurrent isolated sleep paralysis often starts in adolescence, and around 28.3 percent of students apparently experience it.

Moreover, people with poor "sleep hygiene" - for instance, those who sleep too much or too little - may also be more likely to experience sleep paralysis. The authors of a systematic review published in Sleep Medicine Reviews note:

"Specifically, excessively short (fewer than 6 hours) or long (over 9 hours) sleep duration and napping, especially long naps (over 2 hours), were associated with increased odds of sleep paralysis."

"Long self-reported sleep latency [how long it takes to fall asleep] (over 30 minutes) and difficulty initiating sleep were related to an increased likelihood of reporting sleep paralysis," they add.

Are mental health issues to blame?

Given the frightening nature of the most of the hallucinations associated with sleep paralysis, many have wondered whether individuals experiencing mental health issues - such as depression or anxiety - are more susceptible to these experiences.

The results of existing research, however, are mixed. Some have argued that individuals who have experienced abuse in early life - whether or not they remember it - may be more exposed to sleep paralysis.
According to the study that was published in Sleep Medicine Reviews, "Levels of waking state dissociative experiences, involving depersonalisation, derealisation, and amnesia, were found to be related to both sleep paralysis frequency and the frequency/intensity of all three hallucination types."
But links to other neurological and psychiatric disorders are more uncertain.

The authors of a study that was published in the journal Consciousness and Cognition note that previous research has tried to make a case that bipolar disorder, post-traumatic stress disorder, depression, panic disorder, and generalized anxiety disorder - to name but a few - may play a role in sleep paralysis.

However, they report that their analysis of the available data has revealed "no general relationship between [isolated sleep paralysis] and major psychopathology."

Instead, they decided to focus on the most common "symptom" of sleep paralysis - that is, sensed presence hallucinations that induce a feeling of fear - and explained that there may be a link between it and what they call "passive social imagery."

Passive social imagery refers to the experience of individuals who are prone to being more socially anxious, and to imagining themselves in embarrassing or distressing social situations as the passive victim on the receiving end of abuse.

These individuals, the researchers suggest, appear to be more at risk of experiencing distress due to sensed presence hallucinations.

What can you do to prevent it?

Prevention and coping strategies for sleep paralysis are, unfortunately, mostly anecdotal, but there are some methods that seem to have been repeatedly validated by many individuals who say that they - usually or often - work for them.

These include:

trying not to fall asleep on on your back, since studies have associated episodes of sleep paralysis with lying on one's back when going to sleep

trying to ensure, on a regular basis, that your sleep will not be disrupted, since repeatedly waking up during the night has been flagged up as a potential risk factor

avoiding overuse of stimulants, such as tobacco and alcohol - coffee, surprisingly, has not been deemed risky in this context - though the evidence that these affect the chances of experiencing sleep paralysis is mixed

learning meditation and muscle relaxation techniques may help you to better cope with the experience

persisting in the attempt "to move extremities," such as fingers or toes, during sleep paralysis also seems to help disrupt the experience

Finally, if you regularly experience sleep paralysis with "sensed presence" and you think that this may be related to other experiences of anxiety in your day-to-day life, then it may be worth considering cognitive behavioral therapy.

According to the authors of the Consciousness and Cognition study, there is a distinct "possibility that frightening [isolated sleep paralysis] sensed presence experiences [...] may contribute to maintenance of an individual's negative social imagery biases."
If that is the case, they argue, "cognitive behavioral treatment of [these] experiences could help to alleviate the more general social imagery dysfunction," which may improve the overall situation.

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Sleep paralysis: What is it, and how can you cope with it?

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If you buy something through a link on this page, we may earn a small commission. How this works. You wake up in the middle of the night, convinced that an evil figure is lying in wait. You attempt to move, but your body just will not budge.

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Academic Journal Article: What we know about sleep paralysis 

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Academic Journal Article: What we know about sleep paralysis 

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Symptomatology of the disorder is very diverse. There are both psychological symptoms in the form of hypnopompic and hypnagogic hallucinations as well as somatic ones.  The prevention sleep paralysis can be achieved with a change in lifestyle, as well as with the use pharmacotherapy and psychotherapy. Due to the fact that pharmacological treatment is reserved only for the most serious cases. It is necessary to continue the research.

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Academic Journal Article: Sleep paralysis Hallucinations (left and right brain)

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Academic Journal Article: Sleep paralysis Hallucinations (left and right brain)

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There are 3 types of hallucinations that are explained in this article. 1 Vestibular-motor, feeling sensations of floating, flying, spinning, and falling. 2 Intruder, feeling a sense of an alien presence accompanied or followed by visual, auditory, and tactile hallucinations. 3 Incubus, experiencing difficulties breathing, choking, strangulation, suffocation, bodily pressure, and pain.

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Formal Source: Common symptoms  of sleep paralysis

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Formal Source: Common symptoms  of sleep paralysis

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Hallucinations associated with sleep paralysis can be divided into four categories: visual, auditory, olfactory, and tactile experiences. The experience of auditory hallucinations in sleep paralysis can range from the routine to the bizarre.
One of the most often reported phenomena of sleep paralysis is a tactile hallucination, the experience of being touched when you are not.
Some people with sleep paralysis describe tingling, numbness, or a vibrating sensation. The least common hallucination in sleep paralysis is of an olfactory nature, relating to your sense of smell.

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EEK! What Are the Most Common (And Scary) Symptoms of Sleep Paralysis?

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Sleep paralysis hallucinations happen during REM sleep. People see, hear, or feel things that aren’t there. Learn how to prevent sleep paralysis.