When Fear Strikes In Your Sleep

Updated: Aug 19, 2019

Author: Alina Luk

Imagine waking up in the middle of the night and realizing you were unable to move. What if you found yourself gasping for breath every time you tried to fall asleep? These are all symptoms of sleep paralysis, or the inability to perform voluntary movements upon awakening from sleep. Symptoms of sleep paralysis include hallucinations, muscle paralysis, chest pressure, breathing difficulties, and the inability to move body parts despite being consciously awake. Sleep paralysis is not a new condition; the earliest records of sleep paralysis are marked in historical paintings, like Henry Fuseli’s “The Nightmare” (1781) which depicts a demon sitting on a woman’s chest while she is asleep, and cultural folklore [1].

So why does sleep paralysis occur? In normal sleep, a person’s brain activity slows down before they enter rapid eye movement (REM) sleep. In the REM stage, the brain inhibits the release of neurotransmitters, allowing the body to enter a stage of paralysis. This stage usually ends before one wakes up, but during sleep paralysis, the person wakes up in the middle of this stage in a state of consciousness and paralysis. Furthermore, due to controlled respiration patterns under the REM stage, someone who is experiencing sleep paralysis may suffer from breathing difficulties. Breathing is further constricted by fear from activity in the amygdala, the part of the brain that is responsible for emotions, caused by hallucinations. [1].

Early studies suggested that the inhibitory neurotransmitter, glycine, was responsible for the paralyzation sensation during sleep. However, this conclusion was proven wrong by a 2012 study conducted by Patricia Brooks and John Peever that was published in The Journal of Neuroscience [2]. The study found that paralyzation is an effect of both gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter, and glycine on two motor neuron receptor types in the body, preventing muscle movement. In addition, sleep paralysis is believed to be influenced by factors such as stress, poor sleeping habits, sleeping position, possible sleeping disorders, age [3], and the time that the person falls asleep.

Sleep paralysis isn’t common to everyone, which is one reason why it is particularly interesting to learn and study about. Most often, people are able to sense a presence in their room while they are sleeping, but since those that suffer from sleep paralysis are unable to move or speak, the whole experience becomes extremely frightening. In an article published in Clinical Psychological Science, James Cheyne and Gordon Pennycook conducted a survey on 293 people who showed symptoms of sleep paralysis to measure the amount of post distress that the patients experienced and how these feelings would affect the patient’s functionality the next day. They discovered that post-episode distress was elevated after experiencing sleep paralysis and a significant percentage of patients reported that their functioning the next day was affected, indicating that sleep paralysis could contribute to a significant reduction in productivity [4]. Sleep paralysis also more commonly affects those with traumatic stress, panic disorder, anxiety, and depression. Another study conducted on 862 siblings and twins revealed that sleep paralysis may be hereditary [3].

Sleep studies have advanced human knowledge on sleep disorders and other related issues, but there are still many mysteries about sleep paralysis waiting to be unsolved. As of now, REM sleep disorders are being treated with different drugs, such as Clonazepam, a tranquilizer. Less severe cases of sleep paralysis can be resolved by maintaining a regular sleeping schedule and reducing stress. It is also possible to treat sleep paralysis by practicing better sleeping habits and seeking professional help. It is important to note that many REM sleep disorders may result in diseases, such as narcolepsy, a disorder which causes one to lose control of sleeping habits. This knowledge gained from sleep studies can promote further understanding of sleep disorders and how the human brain functions under sleep.


[1] Morton K, Mandell S. Paralyzed at Night: Is Sleep Paralysis Normal? End Your Sleep Deprivation. Published 2010. Accessed September 22, 2017.

[2] Brooks PL, Peever JH. Identification of the transmitter and receptor mechanisms responsible for REM sleep paralysis. Journal of Neuroscience. 2012;32(29):9785-9795. doi:10.1523/jneurosci.0482-12.2012.

[3] Bradford A. Sleep Paralysis: Causes, Symptoms & Treatment. LiveScience. Published September 13, 2017. Accessed September 22, 2017.

[4] Cheyne JA. What Predicts Distress After Episodes of Sleep Paralysis? Association for Psychological Science. Published March 1, 2013. Accessed September 22, 2017.

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