Have you ever experienced a nightmare, became conscious, but were unable to move your body? This is a phenomenon known as isolated sleep paralysis that an estimated 5% to 40% of the general population experiences at one point or another throughout their lifetime. During this condition, you may feel extreme fear, notice the fight-or-flight response, attempt to move your arms, legs, or eyelids – but you’re trapped in a torturous state of sheer panic.
The good news is that of all individuals that experience sleep paralysis, the majority experience isolated episodes, whereas only a small percentage (3%) experience recurrent bouts of sleep paralysis. Although this condition isn’t considered a dangerous health problem, it is associated with disrupted REM sleep and neurodegenerative diseases – which may be a cause for concern.
What is sleep paralysis?
Sleep paralysis is defined as a phenomenon in which a person is temporarily unable to move, speak, or “snap out of” a physical paralysis associated with the REM stage of sleep. Sleep paralysis generally occurs during a transitory phase of sleep such as from a waking state to sleep and/or from a sleep state to waking. During sleep paralysis, a person is unable to move their arms, legs, fingers, toes, eyelids, etc. – all limbs that are under conscious control remain temporarily paralyzed.
Although REM-induced physical paralysis may not sound so bad, some cases may last for over an hour. To make things worse, the paralysis is often accompanied by vivid, nightmarish dreams and sometimes hallucinations (e.g. demonic entities). Imagine being semi-conscious, seeing demons (visual hallucinations), feeling as if you’re going to get attacked (triggering the fight-or-flight response), but here’s the kicker – you’re unable to move. (Read: Sleep Paralysis Hallucinations).
This results in a highly torturous experience and makes you feel completely trapped and powerless. Some unlucky people experience chronic cases, others experience isolated incidences of sleep paralysis, while others never experience an episode throughout their entire lifespan. The condition appears to be more common among those with sleep disorders like narcolepsy; 40% of individuals with narcolepsy are thought to experience sleep paralysis.
Sleep paralysis tends to affect men and women in equal proportion, but first-episodes are most likely occur during teenage years (e.g. 13 to 19) or early adulthood (e.g. 19 to 25). Some reports estimate that 36% of all sleep paralysis cases occur between 25 and 44 years of age.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/10214743
Types of Sleep Paralysis
There are two commonly diagnosed types of sleep paralysis including: isolated sleep paralysis (ISP) and recurrent isolated sleep paralysis (RISP). Of the two subtypes, isolated sleep paralysis is significantly more common. It is estimated that only 3% of all sleep paralysis cases are recurrent episodes.
1. Isolated Sleep Paralysis (ISP)
Those that experience isolated sleep paralysis are in the majority compared to those that experience the recurrent subtype. Episodes of isolated sleep paralysis are relatively common and fortunately aren’t very long-lasting by comparison to the recurrent subtype. Those who experience isolated episodes of sleep paralysis tend to notice the paralysis lasts only a couple minutes.
In other words, they aren’t tormented for nearly as long as individuals with the recurrent subtype. Additionally, most people that experience isolated episodes don’t need to worry about experiencing another episode each time they fall asleep. It’s usually a “one and done” type experience. Should another episode be experienced, there’s generally a pretty big time gap between episodes.
- Frequency: Infrequent or Isolated episodes
- Duration: Short (Minutes)
- Likelihood: Common (40% of People)
2. Recurrent Isolated Sleep Paralysis (RISP)
Those that suffer from recurrent isolated sleep paralysis are in the minority. These individuals end up dealing with sleep paralysis that is not only longer-lasting per episode, but is recurrent. In other words, a person with RISP could theoretically be tormented with sleep paralysis for the rest of their lives.
Some notable differences between those with recurrent sleep paralysis and isolated subtypes is that recurrent sleep paralysis cases often experience paralysis exceeding an hour per episode. Additionally this subtype generally is associated with out-of-body experiences (OOBEs). To make things worse, those with the recurrent subtype may experience multiple paralyses during the same night (e.g. back to back).
- Frequency: Recurrent (Chronic)
- Duration: Long (Hours)
- Likelihood: Rare
- Features: Out-of-Body Experiences
Sleep Paralysis Causes
It is important to keep in mind that the factors that contribute to sleep paralysis for one person may be completely different for another. While certain physiological biomarkers may be indicative of a specific subtype (isolated vs. recurrent), more research needs to be conducted to pinpoint the specific mechanisms that give rise to this condition.
Back (Supine) sleep position: There is some evidence that one sleeping position is associated with sleep paralysis more than others. If you often sleep on your back (supine position), you may be at increased risk for experiencing sleep paralysis. It is unknown as to why sleeping on the back increases likelihood of sleep paralysis, but over 50% of sleep paralysis cases are noted as having slept in this position.
Brain waves: It should be considered that a person’s brain waves during sleep may contribute to sleep paralysis. A study by Takeuchi et al. utilized an EEG to measure a person’s brainwave activity during sleep paralysis. They discovered that during sleep paralysis episodes, there were disproportionate amounts of alpha waves with intermittent spurts of beta waves – particularly in cases of individuals reporting visual hallucinations. This means that a person is consciously aware, yet physically trapped in a state of REM-induced muscle paralysis.
Chaotic sleep schedule: Those with a highly variable sleep schedule or individuals that travel frequently and aren’t able to adjust to new time zones may end up with sleep paralysis. If you work shift work or don’t have a strict bedtime and wake time, you may be at increased risk of sleep paralysis. In fact, not having a set sleep schedule to which your body (i.e. circadian rhythm) can adjust, may lead to sleep disruptions and an abnormal sleep cycle.
Drugs: It is known that using various drugs, whether they be pharmaceutical, over-the-counter, or illicit could theoretically contribute to cases of sleep paralysis. Even alcohol has been speculated as being a potential causative agent due to the fact that it can disrupt various stages of sleep. Some sources believe that substance abuse, medications (particularly psychiatric), and usage of psychostimulants (ADHD medications) may increase likelihood of sleep paralysis.
Faulty neurotransmission: It is believed that various levels of neurotransmitters may increase a person’s susceptibility to sleep paralysis. Particularly, it is thought that both GABA (an inhibitory neurotransmitter) and glycine may be responsible for sleep paralysis. It is known that nerve receptors responsible for regulating both GABA and glycine can be “shut off” in mice, and sleep paralysis stops. Alterations in GABA and/or glycine neurotransmission, which may disrupt sleep and/or contribute to sleep paralysis.
Genetic predisposition: Many experts believe that there may be various genetic polymorphisms responsible for causing sleep paralysis. There is evidence that if someone in your immediate family experiences sleep paralysis, you are also more likely to experience the condition. There is likely a genetic component, and with knowledge of epigenetics, it could be theorized that healthy sleeping habits may “turn off” genes responsible for causing sleep paralysis.
Leg cramps: Those that are prone to muscle cramps, particularly leg cramps may be at increased risk of sleep paralysis. While it is unknown as to how leg cramps contribute to the development of sleep paralysis, it is known that they are linked. Perhaps reducing the soreness and treating cramps prior to falling asleep may minimize the occurrence susceptibility to sleep paralysis.
Mental illness: Those suffering from mental illness such as: anxiety disorders, bipolar disorder, depression, and/or schizophrenia may be more prone to sleep paralysis. These conditions are characterized by sleep disruptions, neurotransmitter fluctuations, and are often medicated with potent psychiatric drugs – which could easily increase likelihood of sleep paralysis. Of individuals with anxiety disorders, it is thought that 1/5 will suffer from sleep paralysis.
In particular, some researchers believe there may be a link between social anxiety disorders and sleep paralysis. Anxiety disorders are characterized by an intense irrational fear of non-threatening situations. There may be some common neural underpinnings that make those with anxiety disorders more susceptible to sleep paralysis.
Other studies have found that those with depression are at increased risk of sleep paralysis. Upon investigation, researchers discovered that antidepressants and anxiety were not indicative of sleep paralysis among those who were depressed. This suggests that certain neurophysiological correlates of depression may increase susceptibility to sleep paralysis.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/16099138
- Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2800990/
Neurological conditions: Those with neurological disorders like migraines and epilepsy may be more prone to sleep paralysis than average. There have been reports of individuals experiencing sleep paralysis prior to a migraine, as well as reports of individuals experiencing migraines during and/or after sleep paralysis. Intense migraines may interrupt a person’s REM sleep, which could be how they increase susceptibility of sleep paralysis.
Neurodegenerative diseases: Those with various forms of neurodegenerative diseases (e.g. dementia) may be at increased likelihood for experiencing sleep paralysis. It is up for debate as to whether the neurodegenerative disease caused the sleep paralysis, vice versa, or if they occur simultaneously. Research has demonstrated that sleep paralysis (a result of R.E.M. disruption) may exacerbate neurodegeneration.
Nerve receptors: Researchers from the University of Toronto discovered that nerve receptors may be responsible for sleep paralysis. Patricia Brooks and John Peever analyzed metabotropic GABAB as well as ionotropic GABAA/glycine. They realized that ionotropic GABAA/glycine interacts with glycine as well as GABA (gamma-aminobutyric acid). GABAB interacts with GABA, but does not respond to glycine. In rodent tests, sleep paralysis was effectively prevented when both GABAB and GABAA/glycine receptors were simultaneously “shut down.”
- Source: http://www.jneurosci.org/content/32/29/9785.full
Sleep disruption: It is well-documented that sleep cycle disruption, particularly to the REM (rapid-eye movement) stages of sleep is associated with sleep paralysis. During REM sleep, a person’s body becomes paralyzed or unable to move, yet may be experiencing an intense dream (or nightmare). This results in the individual feeling helpless and unable to move, yet consciously aware.
It’s as if the brain’s homeostatic sleep cycling has gone askew. A report in 2002 suggested that disrupting a person’s sleep cycle can significantly bolster risk of sleep paralysis. Researchers were able to intentionally induce sleep paralysis in healthy volunteers by restricting them of REM sleep. They accomplished this feat by waking them immediately as they entered REM.
This lead to sudden-onset REM, in which healthy participants “skipped” other stages of sleep and directly entered REM sleep from a waking state. Frequent sleep disruptions, particularly of the REM stage, may lead to a person entering REM directly from a waking state, and thus upping the likelihood that they’ll experience sleep paralysis.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/11833865
Sleep deprivation: Those that expose themselves to sleep deprivation, particularly over an extended term will alter their sleep cycle and circadian rhythm. These alterations are generally considered detrimental, and may be a direct cause of sleep paralysis. Chronic sleep deprivation is likely to change neurotransmitter concentrations, brainwave activity, regional blood flow, etc. All of these changes stemming from sleep deprivation could increase your chances of sleep paralysis.
Sleep disorders: Those with preexisting sleep disorders such as narcolepsy, shift work sleep disorder or obstructive sleep apnea may be more prone to experiencing sleep paralysis. It is thought that as these conditions disrupt a person’s sleep, they likely also disrupt the R.E.M. portion of the sleep cycle, which can cause isolated or recurrent sleep paralysis.
Stress: It makes sense that high levels of stress or chronic stress could increase susceptibility to sleep paralysis. Sleep paralysis is associated with anxiety disorders, traumatic experiences, and panic. During all of these conditions, the body produces an exaggerated fight-or-flight response, characterized by over-activation of the sympathetic nervous system. Those with high levels of stress may experience a nervous breakdown, sleep problems (e.g. insomnia), and ultimately sleep paralysis.
Trauma: Those that have experienced some sort of trauma (e.g. PTSD) have greater rates of sleep paralysis. It is thought that traumatic experiences may alter brain functioning as well as the sleep cycle. Traumatic experiences often result in excess sleep deprivation, nightmarish dreams, insomnia, and frequent waking throughout the night (disruptions).
Additionally, baseline levels of physiological arousal tend to be greater among individuals that have endured trauma. The increased arousal alone is enough to contribute to sleep paralysis. A 2005 study reported that both PTSD and panic disorders lead to increased rates of sleep paralysis. There appears to be a direct relationship between severity of PTSD and number of sleep paralysis episodes.
- Source: http://www.ncbi.nlm.nih.gov/pubmed/15881273
- Source: http://www.ncbi.nlm.nih.gov/pubmed/16094659
Sleep Paralysis Symptoms
Those experiencing sleep paralysis can experience a variety of symptoms. The most prominent symptoms associated with sleep paralysis include: inability to move (immobility), inability to talk, and conscious perception or awareness. Secondary symptoms can include things like: chest pressure, extreme fear, and hallucinations.
- Anxiety: Most people that experience sleep paralysis also tend to feel anxiety. Anxiety disorders, particularly social anxiety is directly linked to sleep paralysis. During the sleep paralysis episode(s), a person may feel intense anxiety in regards to feeling trapped, nightmarish dreams, or hallucinations.
- Chest pressure: Some individuals notice that during the sleep paralysis episodes that there’s an intense pressure over their chest. This pressure can feel like a stack of weights have piled up atop the chest or as if an esoteric entity is pushing on your chest. This pressure may be related to difficulty breathing during the paralysis.
- Conscious awareness: Certain people remain fully conscious during the sleep paralysis episodes and are able to recall the entire episode. Most people are semi-conscious, meaning they have some degree of awareness or “flashes” of conscious awareness. The sleep paralysis episodes are characterized by alpha waves with intermittent beta bursts on the EEG – so this makes sense.
- Distress: Due to the fact that most cases of sleep paralysis are uncomfortable, most people become highly distressed. The feelings of distress can lead to panic, which triggers the fight-or-flight response – exacerbating the initial distress. Do not be surprised if you become distressed, especially if the episode includes hallucinations and/or is long-lasting.
- Difficulty breathing: You may also have a tough time properly breathing during the sleep paralysis episode. The difficulty breathing may be due to the particular position in which you fell asleep, chest pressure, or as a result of panic.
- Environmental perception: Most people are able to perceive things in their surrounding environment. Think of a person being semi-conscious and semi-unconscious at the same time. It’s almost as if REM sleep is blended with consciousness, leading to a perception of the environment, along with unusual sensory dream-like perceptions.
- Fear: In many cases, the dreams and/or perceptions people experience during sleep paralysis are terrifying. In addition to those terrifying perceptions, a person cannot move nor yell for help. This leads a person to experience feelings of fear and the fight-or-flight response may become activated as panic sets in.
- Feeling “trapped”: In nearly every case of sleep paralysis, a person reports feeling trapped. They are aware or semi-aware of their environment and experience, yet they’re unable to do anything about it. If they’re experiencing a bad dream or hallucination, it becomes intensified due to the fact that their conscious perception is turned on. This trapped feeling can result in panic attacks or a fight-or-flight response.
- Hallucinations: Many people experience auditory hallucinations (hearing voices), visual hallucinations (seeing things), and sometimes tactile hallucinations (feeling things) that aren’t based in reality. In rare cases, a person may even report smelling something that isn’t based in reality (olfactory hallucinations). Common hallucinations reported in cases of sleep paralysis include: animals, buzzing, demons, doors opening, footsteps, pressure, and whispering.
- Out-of-body experience: Some people report experiencing a phenomenon known as an “out-of-body-experience” during their sleep paralysis episodes. This is characterized by perceiving your body from outside your body (e.g. an external perspective). Out-of-body experiences are most commonly associated with the more severe and recurrent subtype of sleep paralysis.
- Immobility: The primary symptom associated with sleep paralysis is an inability to move – you’re completely immobile; hence “paralysis.” Obviously the paralysis is temporary, but it can be highly frustrating feeling as if you’re alert in a bad dream – yet unable to move.
- Inability to talk: Among the most notable and frustrating of symptoms is an inability to talk. Imagine being stuck in a dream or dream-like state, but you’re still conscious and sense that a demon is about to attack your body. Instead of being able to scream for help, you cannot move your mouth and feel tortured.
- Sensed presence: Some people report sensing a presence around their body while they are stuck in sleep paralysis. The presence is generally considered evil or considered to have malicious intentions. A person may not actually see any entity, but they may claim to feel or sense it. In some cases, the presence is actually seen or heard in the form of a hallucination.
- Unusual sensations: There’s no telling what you’ll experience during sleep paralysis, but many people report unusual sensations. Most of the unusual sensations are thought to be a byproduct of REM sleep, yet a person’s conscious awareness gets mixed in. These unusual sensations get perceived by the conscious mind as being “real” when in fact they are a result of chaotic brain activity. Sensations experienced could include: feeling as if you are moving, floating, or being pushed; odd smells or sights; feeling stuck in a dream; or sensing an esoteric entity.
Sleep Paralysis Treatment
If you experience sleep paralysis, particularly a type that is long-lasting and recurrent, you may want to work with a sleep specialist to determine the root cause. In most cases, the cause of sleep paralysis is an unregimented sleep schedule and interrupted sleep cycle. The most obvious fix is to make conscious lifestyle changes to improve the quality and quantity of your sleep. For more information, read the article “How To Stop Sleep Paralysis.”
- Coping techniques: Should you experience an episode of sleep paralysis, many anecdotal reports have suggested mastering various coping techniques. The most reported coping technique is that of consciously trying to wiggle your fingers and/or toes. Some people have had success by focusing on wiggling their fingers – which triggered a “wake up” rather than a paralysis.
- Medical evaluation: Be sure to get a thorough medical evaluation for sleep disorders (e.g. narcolepsy) and neurological conditions. In many cases, undiagnosed medical conditions may be contributing to the sleep paralysis that’s experienced.
- Pharmaceutical drugs: If you’re taking various pharmaceutical drugs and the sleep paralysis occurred after you began taking the medication, consider that it may be the cause. If you aren’t taking any medications, some people have had success with various sleeping pills, SSRIs and tricyclic antidepressants. These may be options to consider if your case is severe.
- Sleep schedule: A regimented sleep schedule is perhaps the best antidote for sleep paralysis. A majority of cases are a result of chaotic, highly variable sleep schedules with (often) interrupted sleep. Create a sleep schedule, stick with it, make sure you’re getting enough sleep and that it’s uninterrupted. This may not be a quick fix, but will likely help considerably over the long-term.
- Supplements: Certain supplements like melatonin may enhance sleep quality and reset the circadian rhythm, particularly for individuals involved in “shift work” and/or experiencing jet lag as a result of frequent travel. You may want to consider taking melatonin and/or other supplements to improve your sleep quality.
Diagnosis of sleep paralysis
It’s relatively easy to self-diagnose the condition of sleep paralysis, but it is very important to follow up with medical professionals to determine whether a condition like narcolepsy or a neurological condition may be contributing to the episodes. If you are still unsure about whether you have sleep paralysis, consult a sleep specialist.
- Isolated Sleep Paralysis (ISP): If you’ve ever consciously noticed an inability to move or speak while falling asleep or upon waking – then you’ve experienced isolated sleep paralysis. This is common and isn’t usually bothersome. Episodes generally only last a minute or two and are unlikely to persist.
- Recurrent Isolated Sleep Paralysis (RISP): If you constantly notice an inability to move or speak when falling asleep or upon waking – you have recurrent isolated sleep paralysis. This is a chronic condition that can provoke anxiety and may lead to a fear of sleeping. Only 3% of all individuals with sleep paralysis have recurrent episodes – and many have a comorbid condition like narcolepsy.
Have you ever experienced sleep paralysis?
If you’ve ever experienced an isolated episode of sleep paralysis or have recurrent bouts of sleep paralysis, feel free to share the details of your experience in the comments section below. You may want to mention when you first experienced an episode of sleep paralysis, how long your episodes typically last, and whether you have discovered any ways to cope with them. If you speculate any particular causes that may have contributed to your sleep paralysis, be sure to mention those as well.