# A waking nightmare: The enigma of sleep paralysis



## David Baxter PhD (Apr 20, 2018)

*A waking nightmare: The enigma of sleep paralysis*
By Maria Cohut, _Medical News Today_ 
April 20, 2018

*In sleep paralysis, your mind wakes up, but your body does not. You may  also experience frightening hallucinations. What is this, and how can we  cope?* 



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.

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 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:


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

"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 2016 study  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.

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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