In humans, most mammals and even birds, sleep occur in repetitive cycles, in which the body fluctuates between two different phases; REM sleep and non-REM sleep. REM sleep (or rapid eye movement sleep) is a distinctive sleep phase which is characterized by the rapid movement of the eyes, minimum muscle tone (residual muscle tension) and tendency to dream vividly.
Lack of REM sleep or irregular sleep cycles can lead to various sleeping disorders. Narcolepsy is one such disorder, in which the sufferer gain a tendency to fall asleep during odd hours. Another condition that one may develop is: sleep paralysis. Sleep paralysis is a temporary inability to move and speak either during Hypnagogia (a transitional state between wakefulness and sleep) or Hypnopompic (just before awakening).
Have you ever experienced anything like that? Even if you didn’t, there is a fair chance that you might encounter at least one episode of sleep paralysis at some point in your lifetime. During one such episode, one may hear or feel things that are not actually present there and it mostly results in fear. Fascinating, isn’t it? Let’s find more interesting details about sleep paralysis.
18. Why does it happen?
Sleep paralysis occurs when a person gains conscious in the middle of REM sleep, while the muscles in the body remain inactive. A single episode of sleep paralysis can occur for somewhere from a couple of seconds to a couple of minutes.
17. Two Types of Sleep Paralysis
Based on years of research, scientists have concluded that sleep paralysis is actually of two types; ISP and RISP. People who are suffering from ISP (or isolated sleep paralysis) will only experience sleep paralysis once or maybe twice in their lifetime. However, in RISP (or recurrent isolated sleep paralysis), a person will encounter more than two episodes.
16. “The Nightmare”
John Henry Fuseli “The Nightmare”
Henry Fuseli’s famous painting “The Nightmare”, which he painted in 1791 is closely associated with sleep paralysis on numerous occasions. The scary little monster may represent the sensation of chest pressure that sufferers often mention as a symptom.
15. You Cannot Wake up During an Episode
If you have ever experienced one such episode, then you may already know that during an episode you can’t possibly do anything to wake yourself. A few studies, however, point out that some may be able to move their toes to some extent or make distinct facial expressions, but you have to let it pass out to be able to completely wake up.
14. It is Harmless, Contrary to Popular Belives
Not a single study points out that sleep paralysis can even be remotely dangerous or be fatal. No matter how intense and frequent are the episodes, sleep paralysis can’t harm you physically and there are no recorded deaths caused purely due to sleep paralysis to date.
13. Demography of Sleep Paralysis
While episodes of sleep paralysis can be experienced by people of all ages, children from age 3 to 13 are somehow less prone to it. Teenagers and adults are relatively more affected by sleep paralysis and can experience episodes until their late thirties, but some may still get one in their old age.
12. Earliest Recorded Cases of Sleep Paralysis dates back to the 10th century
While the earliest recorded cases of the sleep paralysis can be found in the 10th-century Persian medical texts, the first clinical observation, however, was performed by a Dutch physician named Isbrand Diemerbroeck sometime during 1664, who treated an elderly woman suffering from consistent nightmares.
11. It is More Common Than We Think
Sleep paralysis was once thought to be an extremely rare condition, but after many studies conducted in Japan, China, Canada, and the United States, scientists are now confident that about 40% to 50% of the total people in the world experience it at least once in their lifetime. Many studies also indicate that this percentage could even reach more than 60%.
10. Sleeping Position can also Play a Role
Various studies have shown that when someone sleeps in the supine position (on their back) they are more likely to experience episodes of sleep paralysis than people who sleep in a prone position, with chest down.
9. It can Easily be Diagnosed
Though sleep paralysis is usually self-diagnosable, some medical help is required to rule out other potential sleeping disorders in many cases. In those cases, doctors generally look for distinct signs for narcolepsy due to its high chance of coexistence along with sleep paralysis.
There are some reliable techniques such as the fearful isolated sleep paralysis interview and the Munich Parasomnia Screening to diagnose recurrent sleep paralysis in people.
8. Sleep Paralysis is Partially Preventable
While some factors can drastically increase the risk for isolated sleep paralysis, those who are already affected can avoid it by bringing some changes in lifestyle. It is statistically proven fact that by regulating sleep and maintaining sleep hygiene one can reduce the chances of encountering another episode of sleep paralysis in the future.
But in cases where a genetic factor is involved, there is nothing they can possibly do to avert sleep paralysis. Several studies have also indicated that regular meditation might also help patients suffering from sleep paralysis.
7. It is Gender Neutral
Sleep paralysis is gender-neutral and can be experienced in both males and females in equal ratios. Data derived from 35 different studies indicate that about 7.6% of the average population, 28.3% of students and 31.9% of psychiatric patients experienced at least one episode of sleep paralysis at some point in their life.
6. Sleep Paralysis Might Cause “Post Abduction Syndrome”
“Post abduction syndrome” is a widely popular term that is generally used by people, who claim to have been abducted by a non-human life form, to describe the effects of abduction on their bodies. Though it is not recognized by any medical organization, these people tend to develop symptoms much similar to post-traumatic stress disorder.
There are more than one type of hallucinations associated with sleep paralysis. This includes an intruder in the room, a floating sensation and the presence of a monster or demon near you.
According to a neurological hypothesis, complex mechanisms, which are responsible for coordinating body movements and relay information about body posture, get activated during sleep paralysis, but since no actual movement is going on, our mind falsely induces a floating sensation.
4. These Hallucinations Arise Due to Disturbances in Parts of Our Brain
A popular neuro-scientific explanation claims that intruder hallucinations are caused due to a functional disturbance in the multisensory processing of the body at the temporoparietal junction (an area where partial and temporal lobes meet).
During an episode of sleep paralysis, there is a desynchrony between motor-execution and feedback from limbs, which results in the destruction of nerve cells’ connections.
3. Hyper-Vigilance Threat
Hallucinations during an episode of sleep paralysis can be further assisted by hyper-vigilant state of our mind. Hypervigilance is basically an elevated state of sensory responsiveness. Usually what happens is when a person enters the state of paralysis, the emergency response is activated in the midbrain and induce fear of attack and helplessness.
This helplessness can escalate the threat response of one’s body to considerably higher levels than the level associated with normal dreams. Furthermore, it can possibly explain the vivid visions during an episode of sleep paralysis.
2. There is a Genetic Component to Sleep Paralysis
A team of researchers has found a genetic component in sleep paralysis. A study conducted on monozygotic twins shows that if one of them experiences an episode of sleep paralysis, then the other twin is more likely to follow. The result also points out a disruption of functions of some kind at the physiological level.
1. Pathophysiology of Sleep Paralysis
The physiological processes of this condition are still not completely understood, though there are some leading theories regarding its cause. One such theory is based on the premises that sleep paralysis is a parasomnia and it is caused by overlapping of REM phase and waking up phase of the sleep.
In another theory, sleep paralysis is triggered when sleep-regulating neural functions in our body are knocked out of balance in such a manner that they cause different stages of sleep to overlap.