Sleep paralysis is a phenomenon where a person temporarily experiences an inability to move or speak while falling asleep or waking up. It can be accompanied by vivid hallucinations, a feeling of pressure on the chest, and intense fear. Though the experience is frightening, it is not dangerous and usually lasts only a few seconds to a couple of minutes. Understanding how sleep paralysis occurs involves looking at the body's sleep cycle and the factors that can disrupt it.
What Happens During Sleep Paralysis?
To understand how you get sleep paralysis, it helps to know what happens during a normal sleep cycle. The sleep cycle consists of several stages, including non-REM (rapid eye movement) and REM sleep. REM sleep is the stage where dreaming occurs, and during this phase, the body naturally becomes paralyzed—a state called REM atonia. This temporary paralysis prevents the body from physically acting out dreams, protecting both the sleeper and their environment.
Sleep paralysis occurs when a person becomes conscious during REM atonia. In this state, the brain has partially or fully awakened, but the body remains paralyzed. This mismatch between mental alertness and physical immobility is what creates the feeling of being “trapped” in one’s body.
There are two main types of sleep paralysis:
Hypnagogic (predormital) sleep paralysis: Happens while falling asleep.
Hypnopompic (postdormital) sleep paralysis: Happens while waking up.
In both cases, the brain wakes up during REM sleep, but the body has not yet exited its paralyzed state. The result is an eerie state of full awareness without physical control.
Causes and Risk Factors
While anyone can experience sleep paralysis, certain factors make it more likely. These factors typically disturb the natural flow of sleep or increase the likelihood of awakening during REM sleep.
1. Sleep Deprivation
One of the most common causes of sleep paralysis is not getting enough sleep. Sleep deprivation disrupts the sleep cycle and may cause the body to enter REM sleep more quickly and erratically. When REM sleep is irregular, the risk of waking up in the middle of it—while the body is still paralyzed—increases.
Adults generally need 7–9 hours of sleep per night. Failing to meet this need over time increases not just the risk of sleep paralysis, but also the likelihood of other sleep-related issues like insomnia or fragmented sleep.
2. Irregular Sleep Schedule
People who go to bed and wake up at inconsistent times are more likely to experience sleep paralysis. This is especially common among shift workers, students with fluctuating schedules, and people with jet lag. Irregular sleep disrupts the body’s circadian rhythm, the internal clock that regulates sleep and wakefulness.
When the circadian rhythm is out of sync, the body has a harder time transitioning between sleep stages smoothly. This increases the chances of “waking up” mentally while the body remains in REM-induced paralysis.
3. Sleeping Position
Research suggests that sleeping on your back may make sleep paralysis more likely. This position can influence breathing patterns and body mechanics in a way that increases vulnerability to the experience. When lying on the back, the airway can be more easily obstructed, and this may contribute to feelings of pressure or chest tightness during a sleep paralysis episode.
4. Mental Health Conditions
Conditions such as anxiety, depression, and post-traumatic stress disorder (PTSD) are associated with higher rates of sleep paralysis. Emotional stress and trauma affect both sleep quality and REM sleep behavior, which may increase the risk of episodes.
Stressful experiences or ongoing anxiety may also prime the brain for hypervigilance, making it more likely to become partially conscious during sleep. Once awake but still paralyzed, the heightened emotional state can intensify the hallucinations and fear often associated with sleep paralysis.
5. Sleep Disorders
Sleep paralysis is more frequent in people with underlying sleep disorders, particularly:
Narcolepsy: A neurological disorder that causes sudden sleep attacks and disrupts the boundary between sleep and wakefulness. People with narcolepsy often enter REM sleep almost immediately, making sleep paralysis more common.
Sleep apnea: A condition where breathing repeatedly stops during sleep. These interruptions can fragment sleep and increase the chance of waking during REM sleep, leading to paralysis.
Insomnia: Persistent difficulty in falling or staying asleep can contribute to fragmented sleep and REM instability.
6. Substance Use
The use of alcohol, caffeine, nicotine, or certain medications—especially close to bedtime—can interfere with sleep stages. Some drugs suppress REM sleep, leading to a “REM rebound” effect when the body tries to catch up later. This may increase the likelihood of entering REM sleep too abruptly or exiting it abnormally, setting the stage for sleep paralysis.
Genetic and Biological Factors
There is some evidence to suggest that genetics may play a role in susceptibility to sleep paralysis. Studies involving twins and families have found that people with a family history of the condition are more likely to experience it themselves. This suggests that some people may be biologically more prone to irregular transitions between sleep stages.
In addition, certain brain structures and neurotransmitter systems involved in REM sleep regulation may function differently in those who experience recurrent sleep paralysis. More research is needed, but the biological component appears to be significant in some cases.
Can You Trigger Sleep Paralysis?
While most people do not intentionally trigger sleep paralysis, some individuals interested in lucid dreaming or out-of-body experiences may experiment with techniques that involve entering a conscious state during REM sleep. These methods—such as sleep interruption, meditation, or wake-induced lucid dreaming (WILD)—can occasionally lead to sleep paralysis as a side effect.
However, for the average person, episodes are usually unintentional and often result from poor sleep habits or underlying stress.
Conclusion
Sleep paralysis occurs when there is a disruption in the natural transitions between sleep and wakefulness, particularly during REM sleep. The most common contributing factors include sleep deprivation, irregular sleep schedules, stress, and sleep disorders such as narcolepsy or sleep apnea. While it can be alarming, sleep paralysis is not harmful and typically resolves on its own.
Improving sleep hygiene—getting enough rest, maintaining a regular schedule, managing stress, and avoiding stimulants—can go a long way in reducing the likelihood of episodes. For those who experience frequent or particularly distressing sleep paralysis, speaking with a healthcare professional or sleep specialist may help identify and treat any underlying issues.
This article was created using OpenAI’s ChatGPT on May 16, 2025 and it was personally reviewed and edited by Brandon Peters, M.D. to ensure its accuracy. This use of augmented intelligence in this way allows the creation of health information that can be trusted.