Sleep paralysis has been experienced by at least half of the population at least once in their lifetime. This fear-inducing occurrence, where one comes face to face with their nightmares, can last from a few seconds to minutes. It can involve visual and auditory hallucinations of an evil spirit or an out-of body feeling. Some have mistaken sleep paralysis for a meeting with a ghost.
In 1867, Dr. Silas Weir Mitchell was the first medical professional to examine sleep paralysis. Although he was the first, it's so common that cultures all across the globe have formulated a paranormal explanation for it. In medieval Europe, it was common to think an incubus, a mythical creature, had visited the victim in the night. In Scandinavia, another creature who sits on rib cages was held accountable. In Turkey, strangling beasts tried to torture you. And, in the southern United States, a hag came for you.
Although it is easier to accuse mythical spirits, what's actually happening is much more difficult to explain. Modern scientists believe that sleep paralysis is caused by an atypical overlap of REM sleep and the waking stage. During a normal REM cycle, one experiences numerous sensory stimuli in the form of a dream, while the brain is unconscious and fully asleep. During the dream, special neurotransmitters are released, paralyzing the muscles. This is known as REM atonia. It's what prevents a person from physically reacting to being chased in a dream. During sleep paralysis, you experience normal components of REM; however, the brain is conscious and wide awake. This causes you to feel that you are experiencing an encounter with frightening presence.
During REM sleep, REM atonia, also removes voluntary control of breathing. Breathing becomes more shallow and rapid, causing one to inhale more carbon dioxide, and thus experience a small blockage of their airway. In sleep paralysis, a combination of the body's fear response to a perceived attack and the brain being awake triggers the body to take in more oxygen, and makes one gasp for air. However, one can't, because REM atonia has removed voluntary control. This experience creates the perception of pressure on the chest, or suffocation.
Sleep paralysis has been linked to narcolepsy. However, people who experience it usually do so infrequently, perhaps only once in their lifetimes. So, sleep well, knowing that the evil creature is not actually coming for you.
Sleep occurs in five stages. About every ninety minutes, we pass through a cycle of these distinct sleep stages. This fact was unknown until Eugene Aserinsky experimented on his son using an EEG. He discovered what we know as REM sleep (rapid eye movement sleep), a recurring sleep stage during which vivid dreams frequently occur. It is also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches), but other body systems are active.
Stage 1 of sleep occurs when we leave the alpha waves, or the relatively slow brain waves, of an awake, relaxed state. We then slip into sleep, a periodic, natural loss of consciousness- as distinct from unconsciousness resulting from a coma, general anesthesia or hibernation. During Stage 1, one may experience fantastic images (falling or floating weightlessly), resembling hallucinations, false sensory experiences, such as seeing something in the absence of an external visual stimulus. Such hypnagogic sensations may later be incorporated into memories.
After relaxing deeply, one begins about twenty minutes of Stage 2 sleep, characterized by the periodic appearance of sleep spindles- bursts of rapid, rhythmic brain-wave activity. Sleep-talking- usually garbled or nonsensical-can occur during Stage 2 or at any other sleep stage.
Then for the next few minutes, one goes through the transitional Stage 3 to the deep sleep of Stage 4. First in Stage 3, and increasingly in Stage 4, the brain emits large slow, delta waves, associated with deep sleep. These two slow-wave stages last for about 30 minutes, during which one would be hard to awaken. At the end of the deep sleep of Stage 4, children may wet the bed or begin sleepwalking. Stages 1-4 encompassed are known as NREM sleep (non-rapid eye movement sleep).
After about an hour, ones leaves behind the stages of NREM sleep, where one ascends from the initial sleep dive. Returning through Stage 3 and Stage 2 for about half the night, one enters REM sleep. For about ten minutes, the brain waves become rapid and saw-toothed. During REM sleep, heart rate rises, breathing becomes rapid and irregular, genital arousal occurs, and every half-minute or so the eyes dart around in a momentary burst of activity behind closed lids. Although the brain’s motor cortex is active during REM sleep, the brainstem blocks its messages, leaving muscles relaxed to the point where one is essentially paralyzed, and cannot be easily awakened. This is why REM sleep is sometimes called paradoxical sleep, with the body internally aroused and externally calm. The sleep cycle repeats itself every ninety minutes. During a normal night’s sleep, periods of Stage 3 and Stage 4 shorten and Stage 2 and REM sleep lengthen.
Anyways, I found this to be interesting.
Have you ever had this experience, or something similar? Share your thoughts in the comments below!
This is terrifying and totally fascinating. This has never happened to me, but now I'm nervous it will happen... Tonight could be the night. I remember learning about the incubus in art history. The incubus has been depicted in paintings throughout history, and I thought it was just a legend or spooky tale. I never realized people actually experience these things! This is seriously freaky!
ReplyDeleteP.S. Kudos on the TedEd video.