Sleep Paralysis: The Science vs. The Supernatural
Scientifically speaking, sleep paralysis is a type of parasomnia, along with night terrors and sleepwalking. Parasomnias are sleep disorders characterized by unusual and undesirable behaviors which occur in between sleep cycles. During sleep paralysis, the body is in a liminal state of consciousness: the individual is awake, but their body is in full paralysis and they are unable to speak. The sound of buzzing, hissing, or vibrations may also be heard and the inability to move can last anywhere from a few seconds to a few minutes. While this is alarming enough, episodes of sleep paralysis are often accompanied by disturbing visual phenomena which are divided into three types:
Intruder hallucinations: the feeling of being watched by an evil, unseen presence and/or sightings of shadow people
Chest pressure hallucinations: the sensation of being choked or suffocated, or the feeling of something sitting on one’s chest
Vestibular-motor hallucinations: feeling as though one is flying or being pulled out of bed
Sleep paralysis can be isolated or recurring and is experienced equally by men and women. Researchers estimate that roughly 20% of people will experience it at some point in their lives, while around 5% have regular episodes. Though the condition is under-researched, experts believe that it may be caused by disruptions in rapid eye movement (REM) sleep. REM occurs about 90 minutes into the sleep cycle, and during this time, the brain is at its most active. Dreams take place during this phase, and the brain paralyzes the limbs to prevent the sleeper from acting out said dreams and injuring themselves.
When a person wakes up while their body is still immobile, sleep paralysis occurs. During this time, the vivid dream images can spill over into reality. The onset can occur when one is falling asleep (hypnagogic) or waking up from sleep (hypnopompic), but some people experience both. Risk factors for sleep paralysis include:
Narcolepsy
Sleep apnea
PTSD
Bipolar disorder
Anxiety disorders
Autism
Substance abuse
Sleep deprivation
Jet lag or other sleep pattern disruptions
Medications for conditions such as ADHD
Sleeping on one’s back - this position makes it easier for the soft palate to collapse and obstruct the airway.
Studies of identical twins have shown that if one experiences sleep paralysis, the same is likely to be true for the other twin, suggesting that there may be a genetic component. Further supporting this hypothesis is the fact that Asians overall have the highest instances of sleep paralysis, while whites have the lowest.
Though the basic features of sleep paralysis are universal, perceptions of the nature of the condition vary greatly by culture. For those who are more superstitious, sleep paralysis has been attributed to everything from ghosts to demons to alien encounters. Many traditions have a concept of the old hag or night hag, and notable examples are the boo hag of Gullah Geechee folklore and the Caribbean soucouyant. In Turkey, it is the nebulous karabasan and in Italy, nocturnal attacks are blamed on an evil witch called the Pandafeche.
A rendering of the boo hag
Different cultures associate sleep paralysis with varying levels of danger, and it is believed that the more a person fears sleep paralysis, the more susceptible they are to having an episode. This theory is something neuroscientist Baland Jalal has studied. A researcher at the University of Cambridge and a Harvard fellow, Jalal examined the differences in how Egyptians and Danes view the phenomenon.
In Egypt, there is a prevalent fear of death by sleep paralysis, which is blamed on djinn. These evil spirits attack humans at their most vulnerable, such as when they are asleep. On the other hand, the Danish have only a mild aversion to sleep paralysis and tend to feel that is caused by psychological factors. Ultimately, Jalal found that people in Cairo, Egypt, were three times more likely to experience sleep paralysis than those in Copenhagen, Denmark.
Whatever the cause of sleep paralysis, and regardless of whether the sights and sounds are "real,": in the moment, when you can't move, can't scream, and there is an unseen presence lurking in a dark corner of your room, it feels real enough.
Sources:
pubmed.ncbi.nlm.nih.gov/32965993/
pubmed.ncbi.nlm.nih.gov/28735779/
journals.sagepub.com/doi/10.1177/1363461520909609
pubmed.ncbi.nlm.nih.gov/25802016/
pbs.org/wgbh/nova/article/the-nightmare-of-sleep-paralysis/
scientificamerican.com/article/sleep-paralysis-and-the-monsters-inside-your-mind/
