Sleep Paralysis

Overview

Sleep Paralysis (SP) is a condition in which wakefulness is induced during atonia, the rapid eye movement (REM) sleep period in which muscle control is lost briefly.[1] Most individuals suffering from SP also experience hallucinations during the episodes that are often vivid, multisensorial, and unpleasant.[2] SP is characterized as a parasomnia, which is a category of behaviors that are abnormal during sleep.[3,4]

Medical experts typically separate SP into two categories:

Isolated sleep paralysis (ISP): when SP is present without connection to an underlying diagnosis of narcolepsy
Recurrent sleep paralysis (RSP): when condition involves multiple SP episodes over time, which can be associated with narcolepsy.[5]

In many cases these two characteristics are combined to describe another condition - recurrent isolated sleep paralysis (RISP), which involves ongoing instances of SP without narcolepsy, though there is no agreement on how often episodes need to occur in order to be classified as recurrent.[6]

The prevalence of SP is around 5-62% worldwide.[7] Given these widely-varying prevalence rates, research on SP should be conducted more consistently, thus helping to determine how it affects individuals’ daily life and how it is connected to mental and physical health conditions.[8] Most affected individuals have single or infrequent episodes that are not associated with narcoleptic syndrome.[9] An episode of SP may occur at least once in a lifetime in 7.6% of healthy individuals.[10]

Signs and symptoms

A key clinical feature of SP is atonia, the inability to move the body or speak.[11] Individuals may recall a frightening arousal while the body’s muscles are temporarily paralyzed, except for breathing and eye movements, although cognitive abilities remain intact.[12] Individuals have also reported chest pressure and distressing emotions like panic or helplessness during an episode.[13] Around 75% of SP episodes include unique hallucinations that are different from typical dreams. These hallucinations can happen when falling asleep (hypnagogic) or when waking up (hypnopompic). There are three main types of hallucinations during SP:

Intruder Hallucinations: These involve sensing a dangerous person/presence in the room
Chest Pressure Hallucinations: These may incite the feeling of being suffocated or that something heavy is on your chest; these often occur with intruder hallucinations
Vestibular-Motor (V-M) Hallucinations: These can include feelings of movement, (e.g., flying) or out-of-body sensations.[14]

An episode usually lasts for a few minutes and improves spontaneously or with outside triggers, such as getting touched or moved.[15,16] Feeling fatigued or excessively sleepy the day after experiencing an episode of SP is also common.[17]

Causes and risk factors

The causes of SP are likely to be multifactorial, although the physiological mechanisms underlying SP are unknown.[18]

Key features that may be associated with SP include:

Medical Conditions:

Hypertension
Idiopathic hypersomnia
Insufficient sleep syndrome
Narcolepsy
Obstructive sleep apnea
Alcohol use
Wilson’s disease

Sleep Factors:

Not getting enough sleep
Disruptions in the body’s internal clock (e.g., jet lag, shift work disorder)
Exploding head syndrome (EHS)

Personality Factors:

Higher levels of dissociation, imaginativeness, beliefs in the paranormal/supernatural

Psychiatric Comorbidities:

Trauma histories and PTSD
Elevated anxiety sensitivity
Panic disorder, generalized anxiety disorder, death anxiety, social anxiety

However, we should note that causal links between these factors and SP are unclear.[19] It is thus important for clinicians to understand factors that may influence the frequency and intensity of episodes.[20]

Diagnoses

Clinical Diagnosis

The formal diagnosis of SP as a condition is conducted according to the International Classification of Sleep Disorders (ICSD)-3.[21] However, due to inconsistencies between diagnostic journals, only some clinicians have been trained to diagnose SP. A detailed procedure is recommended.[22] Clinicians may want to establish the presence of isolated SP episodes, since they are necessary to establish the diagnosis of SP even though individual episodes are not diagnosable on their own. The presence of SP is structured upon clinical interviews and/or questionnaires conducted by licensed medical professionals.[23,24] According to the current ICSD-3 criteria, SP consists of multiple episodes of isolated SP that are connected with significant distress that affect your daily life (e.g., anxiety related to sleeping/the bedroom).[25]

Differential Diagnosis

Because SP can be related to other medical conditions as aforementioned, it is important that differential diagnosis on these medical conditions is conducted depending on an individual’s presentation of the condition, overall health, and history of previous conditions.

It is also crucial to highlight the distinction between SP and narcolepsy. These conditions share similarities, because SP can be a key characteristic of narcolepsy, and previous to the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), SP was included in the criteria for the diagnosis of narcolepsy.[26] Therefore, it is essential to determine whether or not one’s SP is linked to the more significant issue of narcolepsy.

Mental health implications

For most individuals, sleep paralysis is not considered dangerous. While it is a benign condition on its own, the increased fear experienced during an SP episode could potentially contribute to anxiety disorders in certain individuals.[27] Additionally, SP is also associated with excessive daytime sleepiness, worsened sleep quality, and impaired mental health-related quality of life - factors that all additionally contribute to the risk of sleep paralysis.[28]

Treatment

Generally, treatment for sleep paralysis should start with speaking to a health professional in order to identify and address underlying issues that may be contributing to the frequency and severity of the episodes.[29] However, limited research has been done on the efficacy of treatments for SP, specifically.[30] Below are some recommendations based on past studies of narcolepsy, limited case studies, and conclusions from basic research findings on SP.[31]

Sleep Hygiene: Because the connection between sleep paralysis and general sleeping problems is common, improving sleep hygiene is often a priority when preventing future SP episodes.[32]
Pharmacological Treatment: Since isolated SP and related hallucinations usually do not require treatment, and few studies exist regarding pharmacological treatments for this condition, there are unfortunately few evaluations on drugs for SP and their outcomes. Most of the pharmacological agents used to treat SP are used in the context of suppressing narcolepsy symptoms.[33] Some of the most commonly used treatments are tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRI), which are hypothesized to suppress REM sleep, and are also commonly used to suppress other symptoms of narcolepsy.[34]
Psychotherapeutic Treatment:

Psychoeducation and Reassurance: One way clinicians can help individuals work past SP is by reassuring and talking them through what happens during an episode. Often, individuals can feel embarrassed or attribute their experiences to unusual causes (e.g., “going crazy”, paranormal events). Normalizing SP, even without formal treatment, can have a positive impact.[35]
Insomnia Treatment: Since fragmented or disturbed sleep is one of the biggest risk factors of SP, making simple changes to sleep behavior can help alleviate SP. Following sleep hygiene practices or specific advice like not sleeping on your back can be useful. If SP is accompanied by insomnia, a dedicated treatment plan for insomnia might be beneficial.[36]
Cognitive Behavioral Therapy (CBT): SP can also be treated based on a treatment manual for SP, “Cognitive-Behavioral Therapy for Isolated Sleep Paralysis.” This is a short-term therapy (five sessions) based on previous research on sleep paralysis and insomnia treatments. It includes strategies for managing SP, such as techniques to relax during episodes, disrupting episodes in real-time, handling frightening hallucinations, challenging catastrophic thoughts, and mentally practicing successful ways to resolve SP.[37,38]

If you suspect that you or a loved one are demonstrating signs of or experiencing disturbances due to sleep paralysis, please reach out to a licensed mental health professional (e.g., psychiatrist, therapist, clinical psychologist) or your primary care physician for guidance and support.

Contributed by: Mai Tran

Editor: Jennifer (Ghahari) Smith, Ph.D.

References

1 Brooks, P. L., & Peever, J. H. (2008). Unraveling the mechanisms of REM sleep atonia. Nature and Science of Sleep, 10, 355-367. https://pubmed.ncbi.nlm.nih.gov/19226735/

2 What is Sleep Paralysis? (2020, November 19). Sleep Foundation. https://www.sleepfoundation.org/parasomnias/sleep-paralysis

3 Singh, S., Kaur, H., Singh, S., & Khawaja, I. (n.d.). Parasomnias: A Comprehensive Review. Cureus, 10(12), e3807. https://doi.org/10.7759/cureus.3807

4 Sateia, M. J. (2014). International Classification of Sleep Disorders-Third Edition. Chest, 146(5), 1387–1394. doi:10.1378/chest.14-0970

5 Denis, D., French, C. C., & Gregory, A. M. (2018). A systematic review of variables associated with sleep paralysis. Sleep Medicine Reviews, 38, 141–157. https://pubmed.ncbi.nlm.nih.gov/28735779/

6 Ibid.

7 Dahlitz, M., & Parkes, J. D. (1993). Sleep paralysis. The Lancet, 341(8842), 406–407. https://doi.org/10.1016/0140-6736(93)92992-3

8 Sharpless, B. A., & Barber, J. P. (2011). Lifetime Prevalence Rates of Sleep Paralysis: A Systematic Review. Sleep Medicine Reviews, 15(5), 311–315. https://doi.org/10.1016/j.smrv.2011.01.007

9 Ibid.

10 Malhotra, R. K., & Avidan, A. Y. (2012). Parasomnias and Their Mimics. Neurologic Clinics, 30(4), 1067–1094. doi:10.1016/j.ncl.2012.08.016

11 McCarter, S. J., St Louis, E. K., & Boeve, B. F. (2012). REM Sleep Behavior Disorder and REM Sleep Without Atonia as an Early Manifestation of Degenerative Neurological Disease. Current Neurology and Neuroscience Reports, 12(2), 182–192. https://doi.org/10.1007/s11910-012-0253-z

12 Malhotra et al. (2012)

13 Sleep Foundation (2020)

14 Ibid.

15 Isolated sleep paralysis Information | Mount Sinai—New York. (n.d.). Mount Sinai Health System. https://www.mountsinai.org/health-library/diseases-conditions/isolated-sleep-paralysis

16 Malhotra et al. (2012)

17 Sleep foundation (2020)

18 Olunu, E., Kimo, R., Onigbinde, E. O., Akpanobong, M.-A. U., Enang, I. E., Osanakpo, M., Monday, I. T., Otohinoyi, D. A., & Fakoya, A. O. J. (2018). Sleep Paralysis, a Medical Condition with a Diverse Cultural Interpretation. International Journal of Applied and Basic Medical Research, 8(3), 137–142. https://doi.org/10.4103/ijabmr.IJABMR_19_18

19 Sharpless, B. A. (2016). A clinician’s guide to recurrent isolated sleep paralysis. Neuropsychiatric Disease and Treatment, 12, 1761–1767. https://doi.org/10.2147/NDT.S100307

20 Muzammil MA, Syed AR, Farooq MH, Ahmed S, Qazi MH, Patel T, Khatri M, Zaman MU, Nadeem T, Tanveer F, Kumar U, Varrassi G, Shah AA. Frequency and Factors of Sleep Paralysis Among Medical Students of Karachi. Cureus. 2023 Jul 11;15(7):e41722. doi: 10.7759/cureus.41722. PMID: 37575779; PMCID: PMC10414800.

21 ICSD-3 (2014)

22 Sharpless (2016)

23 Ibid.

24 Farooq M, Anjum F. Sleep Paralysis. [Updated 2023 Apr 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK562322/

25 ICSD-3 (2014)

26 Ruoff C, Rye D. The ICSD-3 and DSM-5 guidelines for diagnosing narcolepsy: clinical relevance and practicality. Curr Med Res Opin. 2016 Oct;32(10):1611-1622. doi: 10.1080/03007995.2016.1208643. Epub 2016 Jul 20. PMID: 27359185.

27 Farooq & Anjum (2023)

28 Hsieh SW, Lai CL, Liu CK, Lan SH, Hsu CY. Isolated sleep paralysis linked to impaired nocturnal sleep quality and health-related quality of life in Chinese-Taiwanese patients with obstructive sleep apnea. Qual Life Res. 2010 Nov;19(9):1265-72. doi: 10.1007/s11136-010-9695-4. Epub 2010 Jun 26. PMID: 20577906.

29 Sleep Foundation (2020)

30 Farooq & Anjum (2023)

31 Sharpless (2016)

32 Strickland SR. Sleep disorders. InnovAiT. 2023;16(1):27-33. doi:10.1177/17557380221131348

33 Sharpless (2016)

34 Koran LM, Raghavan S. Fluoxetine for isolated sleep paralysis. Psychosomatics

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35 Sharpless BA, Doghramji K. Sleep Paralysis: Historical, Psychological, and Medical Perspectives. New York, NY: Oxford University Press; 2015.

36 Edinger JD, Carney CE. Overcoming Insomnia: A Cognitive-Behavioral Therapy Approach. New York: Oxford University Press; 2008.

37 Sharpless (2016)

38 Jalal, B., Moruzzi, L., Zangrandi, A., Filardi, M., Franceschini, C., Pizza, F., & Plazzi, G. (2020). Meditation-Relaxation (MR Therapy) for Sleep Paralysis: A Pilot Study in Patients With Narcolepsy. Frontiers in Neurology, 11, 922. https://doi.org/10.3389/fneur.2020.00922