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 an 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 has 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 was 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 depersonalization, 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 imagine 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.
- trying not to fall asleep 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 — through 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 the 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.