Why Does Sleep Paralysis Happen?

REVIEWED BY

William Maish, MD MBA MPH

Clinical Product Lead

Published

Last updated

Quick answer:

Sleep paralysis occurs when your brain exits REM sleep before your body does, leaving voluntary muscles temporarily locked by neurotransmitters glycine and GABA. About 7.6% of the general population has experienced at least one episode, with rates reaching nearly 28% among students due to sleep deprivation and irregular schedules.

Read more →

Understand what your sleep health results really mean

See your biomarkers in context with a comprehensive panel.

  • CLIA-certified labs
  • HIPAA compliant
  • Personalized health protocol
Book your test

What is sleep paralysis?

The basics of temporary muscle atonia

Sleep paralysis is a state where you become conscious but cannot move or speak. It typically lasts anywhere from a few seconds to two minutes. During an episode, you may also feel pressure on your chest and experience vivid hallucinations.

How it differs from other sleep disorders

Unlike nightmares, sleep paralysis occurs while you are at least partially awake. You are aware of your surroundings, which is what makes the experience so unsettling. It is classified as a REM parasomnia, meaning it arises from disrupted REM sleep transitions rather than from a structural brain problem.

Why does sleep paralysis happen?

REM atonia and the timing mismatch

Every night, when you enter REM sleep, your brainstem sends signals that temporarily paralyze most of your voluntary muscles. This is called REM atonia, and it exists for a good reason: it prevents you from physically acting out your dreams.

Sleep paralysis happens when that protective muscle lockdown persists after your brain has already started waking up. Think of it like a software glitch. The "consciousness" program loads, but the "motor control" program is still in sleep mode.

Neurotransmitters involved

The neurotransmitters glycine and GABA play central roles in maintaining REM atonia. Research published in the Journal of Neuroscience shows that these chemicals actively inhibit motor neurons during REM sleep. When the transition out of REM is disrupted, their inhibitory effects linger, keeping your body frozen while your mind is alert.

Why the transition fails

Fragmented sleep is the most common culprit. When your REM cycles are interrupted repeatedly, the brain's ability to smoothly transition between sleep stages breaks down. Sleep deprivation, jet lag, and shift work all increase the odds of a botched transition.

Join 150,000+ others building better health

Get the science behind better health, every week.

By clicking “Subscribe” you agree to our Terms of Service and Privacy Policy.

What is a sleep paralysis demon?

Hallucinations during partial wakefulness

Many people report seeing a dark figure, feeling an evil presence, or sensing something sitting on their chest. These are hypnagogic or hypnopompic hallucinations, and they happen because the brain regions responsible for generating dream imagery remain active even as you regain awareness.

Your amygdala (the brain's threat-detection center) is highly active during REM sleep. When you wake into paralysis, that heightened threat response collides with your inability to move. The result? Your brain interprets the situation as dangerous and fills in the visual details with a threatening figure.

Cultural interpretations across history

The "sleep paralysis demon" is not a modern invention. Cultures worldwide have described this phenomenon for centuries. In Newfoundland, it was called the "Old Hag." In Japan, kanashibari means "bound by metal." A review in Sleep Medicine Reviews cataloged these descriptions across dozens of cultures, all pointing to the same neurological event.

Common triggers for sleep paralysis

Sleep deprivation and irregular schedules

Not getting enough sleep is the single most reliable trigger. When you are sleep-deprived, your brain compensates by diving into REM sleep faster and more intensely. This REM rebound effect increases the likelihood of a messy sleep-stage transition.

Irregular sleep schedules, like those caused by shift work or jet lag, disrupt your circadian rhythm. Your internal clock loses its grip on when REM should begin and end, creating more opportunities for paralysis episodes.

Stress and anxiety

Elevated cortisol fragments sleep architecture. If you are dealing with chronic stress or sleep anxiety, your REM cycles become shorter and less stable. Studies show a strong correlation between anxiety disorders and recurrent sleep paralysis.

Sleeping on your back

Sleeping in a supine position is linked to more frequent episodes. One theory involves airway mechanics: lying on your back can increase upper airway resistance, leading to subtle breathing disruptions that fragment REM sleep. A study in Sleep and Hypnosis found that supine sleeping was significantly more common during sleep paralysis episodes.

Substances and medications

Certain medications, particularly those that affect serotonin or norepinephrine levels, can alter REM sleep timing. Nicotine and alcohol both fragment sleep and increase the risk of REM-related disruptions.

Who is most likely to experience sleep paralysis?

Demographics and risk factors

A meta-analysis in Sleep Medicine Reviews found that about 7.6% of the general population has experienced sleep paralysis at least once. Among students, the rate jumps to nearly 28%, likely because of irregular schedules and sleep deprivation.

People with psychiatric conditions, especially panic disorder and PTSD, experience it at even higher rates. Sleep apnea and narcolepsy also increase the risk, since both conditions disrupt REM sleep transitions.

Genetic factors

Research suggests a genetic component. A twin study found that genetics account for a significant portion of sleep paralysis susceptibility. If a close family member experiences episodes, your own risk is higher.

Test 150+ biomarkers

Two blood draws. A full picture of your health, explained in plain language.

Book your test

How to reduce sleep paralysis episodes

Prioritize consistent sleep

The most effective prevention strategy is simple: get enough sleep on a regular schedule. Aim for 7 to 9 hours and keep your bedtime and wake time consistent, even on weekends. This helps stabilize your REM cycles and reduces the chance of a botched transition.

Manage stress and anxiety

Since stress is a major trigger, addressing it directly can reduce episodes. Cognitive behavioral therapy (CBT) has shown effectiveness for both sleep anxiety and recurrent sleep paralysis. Mindfulness meditation before bed can also lower pre-sleep arousal levels.

Change your sleep position

If you consistently experience episodes while sleeping on your back, try shifting to your side. A body pillow can help you maintain a lateral position throughout the night. This single change reduces episode frequency for many people.

Limit substances that fragment sleep

Cut off caffeine at least 6 hours before bed. Avoid alcohol close to bedtime, as it disrupts REM architecture even though it may help you fall asleep initially. Review any medications with your care team if you suspect they are affecting your sleep stages.

When to see a doctor

Signs that warrant medical evaluation

Occasional sleep paralysis is common and generally harmless. But if episodes happen frequently (several times a month), cause significant distress, or are accompanied by excessive daytime sleepiness, it is worth seeing a sleep specialist.

Frequent sleep paralysis can be a symptom of narcolepsy, sleep apnea, or an underlying anxiety disorder. A sleep study can help identify whether a deeper issue is driving your episodes.

Treatment options

For persistent cases, doctors may prescribe low-dose SSRIs or tricyclic antidepressants, which suppress REM sleep and reduce episode frequency. CBT-I (cognitive behavioral therapy for insomnia) addresses the sleep habits and anxiety patterns that often underlie recurrent episodes.

Track what's driving your sleep disruptions

Understanding why sleep paralysis happens is the first step. But knowing your body's specific stress and sleep markers can reveal what is making episodes more likely for you. Elevated cortisol, low magnesium, or disrupted thyroid function can all fragment sleep in ways that increase REM transition errors.

Superpower's at-home blood panel measures over 150 biomarkers, including cortisol, magnesium, and thyroid hormones, so you can see exactly what is happening beneath the surface. Pair your results with personalized protocols designed to support better sleep architecture.

Start your Superpower panel today and get the data you need to sleep without fear.

Frequently Asked Questions

References

  1. Hauri PJ (2011). Classification of sleep disorders. *Handbook of clinical neurology*, *99*, 669-78. https://doi.org/10.1016/B978-0-444-52007-4.00001-1
  2. Nih. (n.d.). *Narcolepsy*. https://ninds.nih.gov/health-information/disorders/narcolepsy
  3. Brooks PL, Peever JH (2012). Identification of the transmitter and receptor mechanisms responsible for REM sleep paralysis. *The Journal of neuroscience : the official journal of the Society for Neuroscience*, *32*(29), 9785-95. https://doi.org/10.1523/JNEUROSCI.0482-12.2012
  4. Cheyne JA (2002). Situational factors affecting sleep paralysis and associated hallucinations: position and timing effects. *Journal of sleep research*, *11*(2), 169-77. https://doi.org/10.1046/j.1365-2869.2002.00297.x
  5. Tassi P, Muzet A (2000). Sleep inertia. *Sleep medicine reviews*, *4*(4), 341-353. https://doi.org/10.1053/smrv.2000.0098
  6. Denis D, French CC, Rowe R, Zavos HM, Nolan PM, Parsons MJ, Gregory AM (2015). A twin and molecular genetics study of sleep paralysis and associated factors. *Journal of sleep research*, *24*(4), 438-46. https://doi.org/10.1111/jsr.12282

Led by doctors with 40 years of health and longevity expertise

Dr. Anant Vinjamoori

Dr. Anant Vinjamoori, MD

Chief Longevity Officer, Superpower

Dr. Leigh Erin Connealy

Dr. Leigh Erin Connealy, MD

Clinician & Founder of The Centre for New Medicine

Dr. Robert Lufkin

Dr. Robert Lufkin, MD

Physician & UCLA Medical School Professor, NYT bestselling author

Dr. Abe Malkin

Dr. Abe Malkin, MD

Founder & Medical Director of Concierge MD

Biological age 32 — a Superpower member portraitA health system built around you — test, understand, optimize150+ biomarkers across 2 blood drawsWhat to expect with Superpower — week 1 to month 3Trusted by 64,000+ customers — member reviewsBetter than the status quo — Superpower vs the old way60% of members found something a doctor missed — member survey
Daniel OSuperpower memberDavid LSuperpower memberRachel DSuperpower memberCamelia VSuperpower member

4.6 · 64,000+ members

Superpower health membership

Find early signs of 1,000+ conditions - then act, retest, and see what changed.

$349

/year*

150+ biomarkers annually across baseline + retest

Personalized plan that turns results into action

Superpower AI and on-demand care team

Results in 10 days or less

At-home or 2,000+ labs nationwide**

Yearly membership$0.96 / dayHSA/FSA eligible

*Pricing may vary for members in New York and New Jersey

**At-home labs for an additional cost

What we test

TestosteroneFree T4Vitamin DApoBHbA1cThyroid (TSH)hs-CRPFerritinCortisolFasting insulin

60%

found something a doctor missed

93%

rated it more useful than their checkup

77%

found something new in their results

Superpower member survey, 90 days post action plan (n=143).

How does the Superpower membership work?

We test 150+ biomarkers annually across two blood draws. Your baseline test paints a comprehensive picture of your health, and your dashboard shows what’s working, what needs attention, and what to do next. Superpower AI and your care team help you take action across lifestyle, supplements, and treatments. Then we retest to track your progress and continue refining your plan.

Can I cancel anytime?

Yes. You can cancel anytime, no fees. Your membership stays active through the end of your paid year.

How often should I test?

Your membership includes two blood tests per year: one to establish your baseline, and one to see whether your plan improved biomarkers that were out of range or not yet optimized. You can add other diagnostics anytime through the app or with help from your care team.

When will I get my results?

Book your draw at any of 2,000+ partner labs or at-home. Results are typically ready in about a week and land in the Superpower app.

What the 100+ panel measures

All 101 markers in your annual baseline draw, organized by system. Nothing here is an upsell.

Heart & Vascular Health

26

  • Apolipoprotein B
  • Atherogenic Coefficient
  • Atherogenic Index of Plasma
  • Castelli Risk Index I
  • Castelli Risk Index II
  • HDL Cholesterol
  • LDL Cholesterol
  • LDL/HDL Ratio
  • Cholesterol, Total
  • Non-HDL Cholesterol
  • Cholesterol/HDL Ratio
  • Carbon Dioxide, Total
  • High-sensitivity CRP
  • hsCRP-to-Albumin Ratio (CAR)
  • GGT-to-HDL Cholesterol Ratio
  • LDL-C to Apolipoprotein B Ratio (LDL-C/ApoB)
  • LDL Cholesterol / Total Cholesterol (Mass Ratio)
  • Monocyte-to-HDL Ratio (MHR)
  • Neutrophil-to-HDL Cholesterol Ratio (NHR)
  • Non-HDL Cholesterol-to-Apolipoprotein B Ratio (Non-HDL-C/ApoB)
  • NON-HDL Total Cholesterol Ratio
  • Triglyceride HDL Molar Ratio
  • Triglycerides
  • Triglyceride-to-Apolipoprotein B Ratio (TG/ApoB)
  • TyG Index
  • Uric Acid

Metabolic Health

4

  • Estim. Avg Glu (eAG)
  • Eag (mmol/l)
  • Glucose
  • Hemoglobin A1c

Energy

1

  • Cortisol

Liver Health

15

  • Albumin/Globulin Ratio
  • Albumin
  • Alkaline Phosphatase (ALP)
  • Alanine Aminotransferase (ALT)
  • Aspartate Aminotransferase (AST)
  • Bilirubin Direct
  • Bilirubin Indirect
  • Bilirubin, Total
  • Bilirubin-to-Albumin Ratio
  • Ferritin
  • Ferritin-to-Albumin Ratio
  • y-Glutamyl Transferase (GGT)
  • Globulin, Total
  • Indirect-to-Direct Bilirubin Ratio
  • Protein, Total

Kidney

11

  • Calcium
  • Chloride
  • Corrected Calcium (Albumin-adjusted)
  • Creatinine
  • Estimated Glomerular Filtration Rate (eGFR)
  • Potassium
  • Sodium
  • BUN/Creatinine Ratio
  • Blood Urea Nitrogen (BUN)
  • Urea-to-Creatinine Ratio
  • Uric Acid-to-HDL Cholesterol Ratio (UHR)

Sex Hormones

7

  • DHEA-Sulfate (DHEA-S)
  • Free Androgen Index
  • Sex Hormone Binding Globulin (SHBG)
  • Free Testosterone
  • Testosterone, Bioavailable
  • Testosterone, Total
  • Testosterone-to-Estradiol Ratio (T/E₂)

Thyroid Health

4

  • Free Thyroxine Index
  • T3 Uptake
  • T4 (thyroxine) Total
  • Thyroid-Stimulating Hormone (TSH)

Nutrients

13

  • Vitamin D
  • Red Cell Dist Width (RDW)
  • Hematocrit
  • Hemoglobin
  • Total Iron Binding Capacity (TIBC)
  • Iron
  • Iron Saturation
  • Mean Cell Hemoglobin (MCH)
  • Mean Corpuscular Hemoglobin Concentration (MCHC)
  • Mean Cell Volume (MCV)
  • Platelet-to-WBC Ratio (PWR)
  • Red Blood Cells
  • RDW MCV Ratio

Immune System

12

  • Basophils
  • Baso (Absolute)
  • Eosinophils
  • Eos (Absolute)
  • Lymphocytes
  • Lymphs (Absolute)
  • Monocytes
  • Monocytes (Absolute)
  • Neutrophils
  • Neutrophils (Absolute)
  • Mean Platelet Volume
  • Platelet Count

Inflammation

8

  • Lymphocyte-to-Monocyte Ratio (LMR)
  • Monocyte-to-Lymphocyte Ratio (MLR)
  • Neutrophil-to-Lymphocyte-Platelet Ratio (NLPR)
  • Neutrophil-to-Lymphocyte Ratio (NLR)
  • Platelet-to-Lymphocyte Ratio (PLR)
  • Systemic Immune-Inflammation Index
  • Systemic Inflammation Response Index (SIRI)
  • White Blood Cells
Get my health baseline

The full list of 100+ markers and 8 specialty add-ons available at superpower.com/biomarkers.