Sleep paralysis: a phenomenon clearly explained

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What is sleep paralysis and why it happens

Sleep paralysis is a state in which the person becomes mentally awake while the body still remains in typical REM sleep paralysis. At this moment, one is completely aware of the environment, but unable to move or speak (Farooq & Anjum, 2023).

This condition results from a lack of synchronization between brain awakening and the end of REM muscle atony: the mind activates, but the body “delays” re-ignition. Scholars define it as a “dissociation” between consciousness and motor control (Jalal & Hinton, 2020).

Often, this immobility is accompanied by visual, auditory, or tactile hallucinations. Many people report feeling a presence in the room, seeing shadows or figures, or feeling intense chest pressure, called “incubus phenomenon” (Farooq & Anjum, 2023; Jalal, 2016). These experiences result from a kind of emotional hyper-activation typical of REM sleep while the person is in a state of partial consciousness (Sharpless, 2016).

How it manifests itself — what those who experience it feel

During an episode the person experiences:

• Lucid Environmental Awareness (MedlinePlus, 2022)

• Complete inability to move the body or speak (Farooq & Anjum, 2023)

• Scary or Intrusive Hallucinations (Jalal, 2016)

• Feeling of oppression or difficulty breathing (Sharpless, 2016)

• Intense fear or agony, even if the episode lasts a few seconds or minutes (Jalal & Hinton, 2020)

In the long term, recurrent episodes can lead to fear of sleep, insomnia, anxiety and anticipatory worry (Denis et al., 2018).

How widespread is it and who can do it

Sleep paralysis is much more common than you might think. A meta-analysis shows that approximately 30% of people experience at least one episode in their lifetime (Denis et al., 2018). Among students and young adults, the prevalence can reach 37–40%, probably due to stress, irregular schedules and sleep deprivation (Paci et al., 2024). Among the main risk factors we find:

• Poor sleep quality;

• High stress and anxiety;

• Irregular sleep-wake rhythms;

• Family predisposition;

• Sleep disorders such as insomnia (Farooq & Anjum, 2023).

What happens in the brain

During REM sleep, the brain activates a mechanism that “deactivates” muscles to avoid moving while dreaming. This atony is essential and physiological (Brooks & Peever, 2012). However, when the awakening of consciousness occurs before the cessation of atony, the person remains trapped in a hybrid state: consciousness + muscle paralysis.

In some cases, vigilance-related activity of the cerebral cortex is activated while emotional circuits —such as the amygdala— remain in REM mode, generating an amplified perception of fear and contributing to threatening hallucinations (Jalal & Hinton, 2020). Other studies suggest that breathing may temporarily become less effective, increasing the sensation of suffocation (Sharpless, 2016).

How can it be prevented or managed

There is no safe way to stop an episode while it is happening, but it is possible to reduce its frequency and intensity. The most effective methods include:

• Maintain regular sleep hours.

• Avoid sleep deprivation or irregular sleep;

• Reduce stress;

• Avoid alcohol and stimulants before sleeping.

• Practice relaxation and deep breathing (Farooq & Anjum, 2023).

There are targeted psychological interventions, such as Meditation-Relaxation Therapy, that have been shown to help, in some cases, reduce anxiety associated with episodes (Jalal, 2016).

Why it's important to know

Sleep paralysis has been interpreted for centuries as a supernatural phenomenon. In many cultures, there is the image of the “night demon” or “nightmare” sitting on the person's chest (Sharpless, 2016).

Knowing that it is a neurological phenomenon, common and generally harmless, can significantly reduce fear and prevent sleep-related anxiety. Knowing the mechanisms that cause it also allows us to intervene on the triggering factors.

Bibliographic References 

Brooks, P. L., & Peever, J. H. (2012). Identification of the transmitter and receptor mechanisms responsible for REM sleep paralysis. Journal of Neuroscience, 32(29), 9785–9795.

Denis, D., French, C. C., & Gregory, A. M. (2018). A systematic review of factors associated with sleep paralysis. Sleep Medicine Reviews, 38, 141–157.

Farooq, M., & Anjum, F. (2023). Sleep paralysis. In StatPearls. StatPearls Publishing.

Jalal, B. (2016). How to make the ghosts in my bedroom disappear? Focusing-oriented therapy for sleep paralysis. Frontiers in Psychology, 7, Article 28.

Jalal, B., & Hinton, D. E. (2020). Sleep paralysis, neurobiological mechanisms, and the cultural neurophenomenology of the “night-mare”. Journal of Sleep Research, 29(6), e12941.

MedlinePlus. (2022). Sleep paralysis. U.S. National Library of Medicine.

Paci, G., Giannotti, F., & Pizza, F. (2024). Sleep paralysis in Italian university students: Prevalence and associated factors. Sleep Medicine, 109, 165–172.

Sharpless, B. A. (2016). A clinician’s guide to recurrent isolated sleep paralysis. Neuropsychiatric Disease and Treatment, 12, 1761–1767.