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The Science Behind Sleep Paralysis

By Rebecca Bettencourt

Envision going to bed like any other night; your room in dark and cold, just how you like it. Wrapped up in your blankets like a burrito, you start to fall asleep. As you are sleeping you suddenly wake up, or so you think. You are laying there mind racing, but unable to move. You feel like a brick of solid cement stuck to your sheets. As the terror of the immobility sets in, you can feel your heart beating as fast as a racehorse; lubb dubb lubb dubb is the sound that fills your ears. Already anxious and afraid from this unusual paralysis, you realize you aren’t alone. Unable to make out the figure in the corner, you try with all your might to get up and run. Yet, you are still lying there. As the dark figure get closer and closer, your heart beats faster and faster, lubbdubblubbdubb. Unexpectedly and abruptly, the figure is now on top of you, grasping their fingers around your throat. You can feel the touch of the rough and jagged skin on your neck, and you trachea collapsing. Struggling to breathe, and unable to fight, you can feel your body start to give up. You take what feels like your last gasp of air. As this air is struggling to get into your lungsYou suddenly wake up. You are alone, and able to move. Although it felt so real, it was only a dream. This is a common example of what a sleep paralysis episode could consist of, and the terrible terrors that come along with the disorder. Sleep paralysis is a haunting sleep disorder that feels like a reality. There is considerable amounts of science that consist of factual evidence of what sleep paralysis is. Notwithstanding the fact that there are many theories about this disorder and the hallucinations associated with it. Today I will be discussing the myths behind the science of sleep paralysis, and what each entails.

Sleep paralysis (SP) is a feeling of being conscious but unable to move. It occurs when a person passes between stages of wakefulness and sleep. From my experience, during these transitions one may be unable to move or speak for a short to long period of time. In “Encyclopedia of Sleep and Dreaming” by Mary A. Carskadon there are definitions, relationships, and the pathophysiology of SP. First, Carskadon defines sleep paralysis as “a brief episode of partial or total paralysis occurring at the beginning or end of a sleep period” (569). SP is an unforgettable experience, which makes these episodes of paralysis even more frightening, especially if one has copious amount of fear and anxiety of it happening again. Carskadon goes on to explain that SP is frequently accompanied by the sensation of struggling to speak, move, or wake up. Sometimes the subject feels as if they are unable to breathe, and in some cases they feel as if they are dying. Along with these terrifying sensations there are “frightening illusions and hallucinations, such as visions of animals or monsters in the room or a sense that persons are about to enter the room” (569). These hallucinations are vivid and feel like a reality, and usually one can recall these episodes years afterward. As SP happens more frequently to someone their experiences become familiar and less frightening. Throughout medical practices, SP is encountered most often with narcolepsy; there is SP without relation is narcolepsy called isolated sleep paralysis (ISP). The pathophysiology, or the physiological processes associated with SP, has shown that sleep paralysis occurs at the sleep-onset REM (rapid eye movement) period of sleep. Evidence suggests that sleep paralysis is caused by an overlap of REM sleep and wakefulness. The hallucinations accompanying the sleep paralysis are “identical to hypnagogic hallucinations and are probably a consequence of dream imagery occurring during wakefulness” (569). This is one theory on why the hallucinations co-occur with SP; this theory is standing on a platform of evidence and has reasoning behind its science. Sleep paralysis is a haunting sleep disorder that can affect many people, and is caused by a simple overlap of waking up and rapid eye movement.

As stated above, sleep paralysis can happen at the beginning or end of a sleep cycle, and there has been multiple studies on how a sleep paralysis episode will occur. In “Situational Factors Affecting Sleep Paralysis and Associated Hallucinations: Position and Timing Effects” by J.A. Cheyne, she talks about different studies for situational conditions for sleep paralysis. She discusses body position during an episode of sleep paralysis; supine (lying on back), prone (lying on stomach), and left or right lateral decubitus (lying on their side). In these multitude of studies, mass amounts of students were asked if they had experienced SP, and if they had to indicate which position they were in during the episode. The results concluded that the supine position was the most common position during people’s experiences of SP, “the supine position was more than four times more commonly reported” (171). These results are important because a myth, or another theory, about sleep paralysis is avoiding sleeping in the position that your episodes occur in, and this helps support that hypothesis since the supine position is most commonly correlated with SP.

The hallucinations associated with SP do not have factual reasoning behind them. They are commonly believed to reflect dream imagery intruding into waking consciousness. Hallucinations can be accompanied by voices, visual apparitions, and less-frequently sensations of floating or out-of-body experiences. Hallucinatory experiences fall into three major categories; based on frequency and perceived vividness or intensity. The three categories are intruder, incubus, and vestibular-motor (VM) experiences. In “Spatial Characteristics of Hallucinations” by J.A. Cheyne and T.A. Girard, here they explain what each of these separate types of hallucinations consist of. Intruder hallucinations include a sense of not being alone, and are interpreted as threatening entities including humans, demons, and even aliens. These appearances of unexpected and remarkable subjects are “associated with a variety of sensations, including footsteps, whispers, animal sounds, verbal threats, and physical contact, such as being touched or grabbed by the supposed intruder” (283). Intruder hallucinations make these types of dreams feel like a reality, especially because the entity is usually tactile. Intruder and incubus hallucinations are very similar, and usually are categorized as one because of the experiences of threat and assault. The difference is that incubus experiences is that they involve sensations of “bodily contact, including feelings of impeded breathing, choking sensations, strangulation or suffocation, bodily (usually chest) pressure, and pain” (283). These contact hallucinations are positively correlated with fear, and thoughts of impending doom. These two categories of hallucinations associated with SP are some of the most frightening, where VM experiences are often associated with bliss and joy. VM sensations “include experiences of floating and flying, as well as illusory motor movements including locomotion and postural adjustments” (283), which include sitting up, getting out of bed and walking around. Under this category there is also out-of-body experiences and autoscopy (seeing oneself from an external standpoint). These VM sensations are often erotic, where incubus and intruder are fearful.

Throughout my life I have struggled with SP. These dreams have caused a decrease in my overall fitness, and cost me countless hours of sleep. Filled with fear, I couldn’t sleep without feelings of anxiety and fear of when an episode would happen again. Most of my hallucinatory experiences were conclusive with intruder and incubus. My first time experiencing SP it was a mix of all three categories of hallucinations. I was extremely ill, and wasn’t allowed to be alone. I was sleeping downstairs on my living room couch when unexpectedly there was a man dressed in black standing behind my mom while she was asleep on the other couch. I could see him staring at me, but I wasn’t “me.” I was standing to the side watching this scenario take place. I could see my body lying on the couch— but I wasn’t in it. I watched this intruder shoot my mom, and begin to steal items from our house. Before he left he brushed his hand across my face, I could feel it even though I was standing a couple feet away. The chills ran down my spine and I suddenly woke up. My mom was alive, nothing had been taken from our house, but our house had been broken into. So, some myths say that my unconscious mind was trying to comprehend what was happening in reality by making up a scenario in my head. This whole experience still gives me an uneasy feeling. As I’ve gotten older my episodes usually consist of demonic creatures, they either associate with assault or threat. There is no factual reasoning behind my episodes of SP, but some would suggest that I am finding meaning to a reality.

My SP episodes have gotten progressively worse and more frequent, so I had to participate in a sleep study. They found that if I went on a medication for alcoholics and drug addicts, Naltrexone, that I would usually sleep in the light or deep portion of the sleep cycle. This would reduce my amount of REM sleep, causing me to have less occurrences of SP. There have also been studies suggesting ways/theories on how to disrupt or prevent SP. This was extremely intriguing to me; finding new ways to possibly prevent SP is always something I am on the lookout for. In “Isolated Sleep Paralysis: Fear, Prevention and Disruption” by Brian Sharpless and Jessica Grom they propose that disruption is better than prevention. They state that little is known about SP, and there is no empirically supported treatments available. Yet, there has been many attempts to prevent and disrupt SP. The strategies of SP prevention included: “change sleep position, change sleep patterns, relaxation techniques, change diet, eliminate caffeine, try to stop dreaming, exercise, avoid stressful topics and consume caffeine” (137). These strategies were mostly successful in their study, but do not work for everyone. This is a myth on how to prevent SP, and each strategy will work differently depending on the individual. The strategies to disrupt SP included: “attempt to move extremities, calm down, attempt to call out, change sleeping state, become angry/assertive, and engage hallucination (i.e., talk to spirit)” (137). These had relatively higher rates of success. After reading this article I have more insight on things to try when an episode occurs. Regardless, SP is a troubling disorder that affects many individuals; hopefully these myths/theories on how to prevent/disrupt SP can help the victim of SP.

There is a substantial amount of myths and science behind the sleep disorder sleep paralysis. Although there is reasoning behind the vivid imagery and why this disorder occurs, there is no specific reasoning to why people hallucinate these certain scenarios. Hopefully within upcoming years of research they find more information about this disorder, and how to treat it. The fear and anxiety caused from SP will optimistically diminish as resolutions transpire.

Works Cited

Carskadon, Mary A. Encyclopedia of Sleep and Dreaming. Macmillan Library Reference, 1995.

Cheyne, J.A, “Situational Factors Affecting Sleep Paralysis and Associated Hallucinations:  Position and Timing Effects.” Journal of Sleep Research, vol. 11, no. 2, June 2002, pp. 169-177. EBSCOhost, doi:10.1046/j.1365-2869.2002.00297. Accessed 4 November 2017.

Cheyne, J. A. and T. A. Girard. “Spatial Characteristics of Hallucinations Associated with Sleep Paralysis.” Cognitive Neuropsychiatry, vol. 9, no. 4, 2004, pp. 281-300. EBSCOhost, doi: 10.1080/13546800344000264. Accessed 4 November 2017.

Sharpless, Brian Andrew and Jessica Lynn Grom. “Isolated Sleep Paralysis: Fear, Prevention, and Disruption.” Behavioral Sleep Medicine, vol. 14, no. 2, 2016, pp. 134-139. EBSCOhost, doi:10.1080/15402002.2014.963583. Accessed 2 November 2017.