You may have experienced sleep paralysis without realizing it. Don’t move! Science tries to explain this strange and terrifying phenomenon.
You may have already experienced it: you wake up inside your body but all of your motor functions are still asleep. You feel like a prisoner of your own body–you are paralyzed and overwhelmed by anxiety.
Many studies have tried to explore sleep paralysis to estimate the rate of people who experience(d) the phenomenon. Estimates of the prevalence of sleep paralysis vary widely (from 5% to 65% of the population), because of several reasons (limited number of participants, and/or the inclusion of high-risk individuals).Hallucinations help the brain cope with sleep paralysis.Click To Tweet
In 2011, a meta-study combining over 30 studies on sleep paralysis prevalence concluded that around 8% of people experience sleep paralysis. This number rises to 28% in high risk groups and up to 34% in those with anxiety and depression or other psychiatric disorders.
But what are the mechanisms behind this phenomenon?
Sleep Paralysis, a Defense Mechanism
Sleep paralysis is a parasomnia, or a sleep disorder, that can occasionally affect any sleeper, during which a person about to sleep or wake up will be briefly unable to move or speak.
Generally benign and harmless, sleep paralysis can be considered a disease only when it is recurrent or impacts the daily life of the victim.
Sleep paralysis results when the brain switches off muscles, during the phase of rapid eye movement (REM), to protect the body from potential injuries during sleep (as we may try to enact our dreams).
If we wake up during this phase, our motor functions would be still under this naturally-induced paralysis, and as a result, we are aware yet temporarily unable to move.
A few years ago, neuroscientists identified two neurotransmitters that trigger sleep paralysis by inhibiting the action of special brain cells allowing skeletal muscles to remain active.
Lucid Nightmares of Sleep Paralysis, or the “Bedroom Intruder”
If the mechanical side of sleep paralysis is well understood by now, there is however a mystery surrounding dreadful hallucinations experienced during some sleep-paralysis episodes.
It seems that these episodes expose us to our greatest anxieties, as episodes of sleep paralysis can be accompanied by visual and/or auditory hallucinations.
Some people report seeing “something” in the darkness, or feel pressure on their chest, when they are conscious but totally trapped. This “something”, often seemingly supernatural and menacing, can sometimes only be felt. Other times it can be perceived as aggressive, seemingly sitting on the chest of the sleeper in order to strangle them.
In world folklore, the phenomenon of supernatural intruder has given rise to various interpretations: from witches, to incubus and succubus attacks, chest crushers and other demonic entities.
Since the second half of the 20th century, stories started to involve malefic aliens who induce paralysis into their victims to, well, abduct and probe them.
A group of researchers tried to explain the mystery of the “bedroom intruder”. They say that this could be explained by a functional disturbance in the right parietal cortex, the region where the brain holds a neural map of the “self”. They suggest that this ghostly appearance “is the result of a hallucinated projection of the genetically ‘hard-wired’ body image.”
Science and technology could help us get some insights into the workings of the human brain. As we’ve come to know, the brain does use chemicals to stop muscles and we understand why.
Yet, how does the mind interpret it? Perhaps these lucid nightmares are the mind’s way to make sense of sleep paralysis until it wears off and we regain our motor function.