Parasomnia Facts, Causes, and Types

Medically reviewed by
 Dr. Nayantara Santhi

Dr. Nayantara Santhi

Dr. Nayantara Santhi holds an academic position at Northumbria University. After completing her Ph.D. at Northeastern University (Boston, MA), she joined the Division of Sleep Medicine at Harvard Medical School as a post-doctoral fellow to research how sleep and circadian rhythmicity influence our cognitive functioning.

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By Sanchita Sen Certified Sleep Coach

Last Updated On October 11th, 2023
Parasomnia Facts, Causes, and Types

Key Takeaways

  • Understanding Parasomnia: Parasomnia is a sleep disorder characterized by undesirable verbal or physical behaviors or experiences that occur while falling asleep, sleeping, or waking up. These behaviors may include sleepwalking, sleep terrors, sleep-related eating disorders, and more. It can manifest in various forms and at different stages of sleep.
  • Causes of Parasomnia: The causes of parasomnia are not always clear, but they can be attributed to factors such as sleep disruptions, genetics, neurological disorders, psychological trauma, fever, or the side effects of certain medications. Parasomnia can affect both children and adults, with some cases having a genetic component.
  • Types of Parasomnia: Parasomnia includes a range of behaviors, such as sleepwalking (somnambulism), night terrors, sleep-related eating disorders, nightmares, sleep paralysis, and REM sleep behavior disorder (RBD). These conditions can disrupt sleep and lead to various health issues. Treatment for parasomnia may involve education about sleep cycles, good sleep hygiene, and, in some cases, pharmacological intervention.

Talking, walking, yelling, eating, or even driving around in your sleep is possible. These abnormal and disruptive sleep-related behaviors and experiences are known as parasomnia, and may manifest for various reasons.

The word “parasomnia” is derived from the Greek prefix “para” meaning “alongside,” and the Latin noun “somnus” meaning “sleep.”

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Parasomnia is a sleep disorder characterized by undesirable verbal or physical behaviors or experiences that occur while you are falling asleep, sleeping, or waking up. You may or may not remember an episode of parasomnia when you experience it yourself.

“Sleep disorders can have serious consequences on our health and quality of life,” says Dr. Nayantara Santhi. “They can range from complaints of either insufficient sleep or abnormal movements during sleep. The latter are called parasomnias and are defined as undesired physical or behavioral phenomena occurring during sleep. Sleep walking, sleep talking, and night terrors are examples of parasomnias.”

Parasomnia Facts

Your body is not inactive during sleep—your brain and body go through numerous activities during this period. As you progress from a wakeful state to NREM (Non-Rapid Eye Movement) to REM (Rapid Eye Movement), your brain transitions through phases. These transitions do not happen at the switch of a button—it requires reorganization and smooth progression of various neural centers before a specific stage can manifest itself properly.

Through the night you typically experience four to six sleep cycles, with each cycle running through stages 1 through 3 of NREM sleep, followed by REM when your brain becomes more active. During each of these stages, your body experiences physiological changes, like drops in blood pressure, heart rate, and body temperature.

The first sleep cycle takes about 90 minutes to complete, followed by consecutive sleep cycles through the night. In the later sleep cycles, the duration of REM sleep increases. During these transitions, the brain goes through an overlap of stages which can lead to an unstable state, triggering manifestations of parasomnia.

Causes of Parasomnia

There is still a lot to explore in the area of sleep problems and parasomnia. Though its causes are not clear, some instances of parasomnia may be due to certain factors like sleep disruptions, genetics, brain disorders, neurological disorders, deep psychological trauma, or side effects of prescription medications.

Sleep Disruptions and Deprivations

Lack of restful sleep might trigger some episodes of parasomnia. When your body does not get good healthy sleep, the brain may trigger these unpleasant instances. It is important that you maintain good sleep hygiene. External stimuli like loud noise or bright light, or internal stimuli like physical pain or a full bladder may pose as sleep disruptors.


Like many other disorders, parasomnia can be genetic. If one or both parents have experienced frequent episodes of parasomnia, there’s a likely chance that their children will also have similar experiences.


Pediatricians insist on parents reporting any incidents of parasomnia in their children. While taking details about the child’s sleep history, they also check on parents’ experiences to ascertain if the children are genetically predisposed to parasomnia.

Psychological Disorders

Sometimes parasomnia manifests itself in psychological disorders, like depression, bipolar disorder, or autism, and may find it difficult to sleep at night. Lack of a good night’s sleep may trigger certain instances of parasomnia.

Neurological Disorders

Your brain and nerves are very closely connected, so neurological disorders like Parkinson’s disease, narcolepsy, or dementia may sometimes lead to instances of parasomnia.

Deep Psychological Trauma

Incidents like death or separation may have a strong psychological impact on the mind, leading to sleep disruptions which could trigger instances of parasomnia.


The body’s natural thermoregulation is controlled by the brain but may not be as effective in controlling the high temperature triggering episodes of parasomnia. High temperatures from fever may sometimes mess up the brain during sleep, leading to unpleasant experiences of parasomnia. Some people also experience fever dreams when their body temperature is elevated during sleep.

Side Effects of Medicines

Certain medications like antidepressants, lithiums, and thioridazine are known to have an effect on your brain, leading to incidents of parasomnia.

Parasomnia in Children

Children’s brains are the most active compared to adults because of their phases of growth and development. During sleep, the brain is most active. A super active young brain may find it difficult to transition smoothly between different stages of sleep, leading to instances of parasomnia. Sleep is the fifth leading concern reported by parents about their children.

Parasomnia happens due to sleep disruptions and is usually more common in children than in adults. Many pediatric parasomnias are benign and usually fade away with time. Children are more prone to sleep disruptions, which explains why parasomnias are more common in them.

For example, night terrors, sleep talking and sleep walking aren’t uncommon in children.

Types of Parasomnia

Sleepwalking, nightmares, sleep paralysis, and sleep terror disorders are all part of parasomnia and they often leave you feeling scared or exhausted. According to the International Classification of Sleep Disorders (ICSD), parasomnia has been categorized according to the stages of sleep, when they are likely to occur.

NREM State Parasomnia

The common feature of this type of parasomnia is sleep disruptions at frequent intervals, especially during slow-wave sleep which happens in stages 3 and 4 of NREM sleep. They usually occur during the first half of the night. Factors impairing sleep consolidation trigger these instances of parasomnia, more commonly seen in children.

Sleepwalking, or Somnambulism

Sleepwalking, or somnambulism is the act of getting up and moving around during sleep, with eyes wide open. This usually occurs during deep non-REM sleep cycles. Sleepwalkers look awake, but they are actually asleep—they have no memory of wandering around.

Sometimes, sleepers may wake up while sleepwalking, or they may sleepwalk and go back to bed without ever realizing what happened. This is commonly seen in children between the ages of 6 to 12 years, but may also be seen in adults and the elderly. If sleepwalking runs in the family, a recent National Library of Medicine study Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source proves that childhood sleepwalking has familial aggregation.

Sleepwalking can be dangerous because the sleepwalker is unaware of their surroundings and may bump into things or fall. Take steps like putting a gate on the stairs and locking the doors when you have a sleepwalker in the house. There have been rare instances of sleepwalkers going out of the house and sometimes even driving.

Pediatricians recommend parents to keep an eye on children while they sleep, to recognize signs of parasomnia in children if there are any.

Sleep Terrors or Night Terrors

Sleep terrors or night terrors are where the person abruptly wakes up in fear. Sleep terrors or night terrors may be accompanied by crying or screaming with an increased heart rate, breathing, or a flushed face. The person experiencing it may appear to be awake, but they actually have no memory of this.

Episodes of sleep terror are brief, but may sometimes last as long as 30 to 40 minutes after which the person appears to fall back asleep. The whole episode can occur with the affected person having no memory of it.

Like sleepwalking, sleep terrors or night terrors occur during deep NREM sleep, usually in the first half of the night and may run in the family. This is common in children between the ages of 4 to 12 years, but may occasionally occur in adults and the elderly.

Sleep-Related Eating Disorder

Sleep-related eating disorder is an extension of sleepwalking, where people experiencing it are involved in frequent episodes of binge eating and drinking. You may be partially or fully aware of it when you are preparing or eating food, but you remember nothing about these episodes the next morning.

This can be dangerous as you may end up eating something inedible, toxic, frozen, or raw. It can lead to overeating, digestive issues, and obesity. Due to partial consciousness, you may hurt yourself while preparing food—inappropriate use of kitchen appliances can be dangerous.

This disorder is seen in the early hours of the night during deep NREM sleep. Sometimes it may be related to a daytime eating disorder, such as bulimia or anorexia. Side-effects of certain medications, stress, anxiety, depression, or sleep deprivation may sometimes trigger this disorder.

REM State Parasomnia

REM state parasomnia occurs during REM sleep when the brain is active. They are usually experienced during the later part of the night because REM increases through the night. In the early cycles of sleep, REM lasts for 10 minutes, but during the later cycles its duration increases.

Nightmare Disorder

Nightmare disorders involve vivid dreams during sleep, evoking feelings of fear, stress, or anxiety. They happen during REM sleep when the brain is active, so the experiences feel almost real. The person experiencing nightmares tends to wake up abruptly due to extreme fear, stress, or anxiety. They often remember their nightmares in detail and find it difficult to fall asleep because of the adrenaline effects. Nightmares may be caused due to fever, personal grief, physical or psychological trauma, or as a side-effect of medication.

Sleep Paralysis

In sleep paralysis, you are not able to move your body or limbs while your brain is awake. It lasts for a brief period—a few seconds or minutes—but it can feel terrifying because of the paralysis sensation while awake. This happens during transitions between sleep stages and is caused by sleep deprivation, inadequate sleep, or irregular sleep-wake schedules.

REM Sleep Behavior Disorder (RBD)

Those experiencing REM Sleep Behavior Disorders act out their dreams in a dramatic or violent manner. During REM sleep, the body is usually in a state of paralysis known as atonia, but those experiencing this disorder move their body or limbs during dreams. This is generally seen in men above 50, but sometimes children or women may experience it. RBD may pose a threat to a sleep partner because the agitated and violent movement of limbs may cause injury. Side effects of antidepressants can lead to RBD. Sometimes they may be symptomatic of some neurodegenerative diseases like Parkinson’s, or dementia.

Other Types of Parasomnia

These types of parasomnias are not dependent on a particular sleep state. They may happen at any time during sleep cycles.

Exploding Head Syndrome

Exploding head syndrome is when you hear loud, imaginary sounds in your sleep. The cause for this is not known, but stress and sleep deprivation are known to trigger it.

Sleep Bruxism

Sleep Bruxism is the clenching or grinding of teeth during sleep and considered a sleep-related movement disorder. People who experience this are more likely to have other sleep disorders like sleep apnea.

Restless Legs Syndrome (RLS)

Restless Legs Syndrome is an uncomfortable sensation in the legs causing you to move or stretch your legs frequently while you sleep—you may feel itchy, crawly, or pins and needles sensations. These episodes of periodic limb movements interfere and disrupt your sleep.

Periodic Limb Movement Disorder (PLMD)

Periodic Limb Movement Disorder is a sleep disorder characterized by repetitive and involuntary jerking or twitching movements of the legs during sleep. People with PLMD may experience frequent leg movements that can disrupt their sleep and lead to excessive daytime sleepiness.

Unlike RLS, which is characterized by uncomfortable sensations in the legs and an urge to move them while awake, PLMD occurs during sleep and is often not associated with any conscious awareness or discomfort. While RLS and PLMD can coexist, PLMD is considered a distinct condition.

Treatment Options

Depending on the cause and severity of the condition, your health care provider may prescribe sleep medications, therapy, or lifestyle changes. Parasomnia often fades away with time, but sometimes they’re manifestations of a medical condition.

“In most cases, treatment involves basic education about sleep cycling and good sleep hygiene, along with reassurance,” explains Dr. Santhi. But in some instances, for example with REM sleep behavior disorder, pharmacological intervention may be needed.”


Is parasomnia a psychiatric disorder?

Parasomnias are known to be unpleasant experiences, but they are not an indication of a psychiatric disorder. They may be caused due to stress or some other psychological problem. Some forms of parasomnia are very common in children, which disappears over time.

When to consult a doctor for parasomnia?

If episodes of parasomnia are frequently causing disturbances to your normal lifestyle, we recommend consulting a doctor.


Experiences of parasomnia may sound intimidating, but are nothing to be scared of—they are like bad dreams, which disappear over time. If you have parasomnia, try to record their occurrences and consult a doctor if the episodes become more frequent.

About the author

Sanchita Sen is a full-time writer focusing on the sleep health and mattress industry. She is a former journalist who has written numerous articles on the healthcare sector. Some of the topics she has covered include how to lucid dream, fever dreams, melatonin for sleep, and best gel memory foam mattress. Sanchita holds a Master of Arts in Communications from Convergence Institute of Mass Media and Information Technology Studies. She is also a published author, who seeks inspiration from both real life and the world of fiction.

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