What Is Parasomnia?

Parasomnias are types of disturbing disorders that can happen just before you fall asleep, while you’re sleeping, or as you’re waking up.

Parasomnias include:


Nightmares are vivid dreams that can cause fear, terror, and anxiety. They might make you wake suddenly and have a hard time getting back to sleep. You’ll probably remember the episode in detail. Many things can cause nightmares, including illness, anxiety, the loss of a loved one, or reactions to a medication. Talk to your doctor if you have nightmares more than once a week or if they keep you from getting a good night's sleep for a long time.

Night Terrors

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Night terrors, also called sleep terrors, are similar to nightmares but usually happen during deep sleep. They cause you to wake suddenly, feeling terrified and confused. You can’t talk and won’t respond to voices. You might not seem fully awake.

Episodes of this parasomnia last about 15 minutes, and then you’ll probably fall back asleep. You usually won’t remember it the next morning.

People who have night terrors can be a danger to themselves or other people because of body movements that they can’t control. This parasomnia is fairly common in children, mostly between ages 3 and 8.

Adults can also have night terrors, and they may run in families. Strong emotional stress and alcohol use can make adults more likely to have them.


Sleepwalking is when you’re moving around and look awake but are actually asleep. You won’t remember it the next day. Sleepwalking is most common during a stage called deep non-rapid eye movement (non-REM) sleep early in the night. It can also happen during REM sleep in the early morning. This parasomnia mostly happens in children between ages 5 and 12. It tends to stop as children enter the teen years.

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Sleepwalking tends to run in families. It’s not dangerous to wake a sleepwalker, but they might be confused when they wake up. Sleepwalking itself can be risky because the person isn’t aware of where they are and can fall or bump into things.

Confusional Arousals

Confusional arousals usually happen when you wake from a deep sleep during the first part of the night. This parasomnia, which is also known as excessive sleep inertia or sleep drunkenness, makes you very slow when you wake up. You react slowly to commands and may have trouble understanding when someone asks you a question. You probably won’t remember the event the next day.

Rhythmic Movement Disorder

Rhythmic movement disorder happens mostly in children under age 1, often just before they fall asleep. A child may lie flat, lift their head or upper body, and then forcefully hit their head on the pillow. This parasomnia, which doctors also call headbanging, can also involve movements such as rocking on hands and knees.

Sleep Talking

Sleep talking is a sleep-wake transition disorder. This parasomnia usually isn’t dangerous but can disturb bed partners or family members. Sleep talking can involve simple brief sounds or long speeches. The talker probably won’t remember doing it. Things like fever, emotional stress, or other sleep disorders can cause sleep talking.

Nocturnal Leg Cramps

Nocturnal leg cramps are sudden, uncontrolled muscle contractions during rest. They usually happen in your calves. The cramping feeling may last from a few seconds to 10 minutes, but the pain may linger.

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Nocturnal leg camps often happen in middle-aged or older people, but anyone can have them. They’re different from restless legs syndrome, which usually doesn’t involve cramping or pain.

Sometimes, there’s no clear trigger for these cramps. Other times, they’re linked to sitting for a long time, dehydration, overworked muscles, or physical problems like flat feet.

Sleep Paralysis

When you have sleep paralysis, you can’t move while falling asleep or while waking up. The paralysis can be partial or total. Sleep paralysis can run in families, but experts aren’t sure what causes it.

This parasomnia isn’t dangerous. It can be scary if you don’t know what’s happening. A sound or touch might end the episode, making you able to move again within minutes. Some people have it only once, but others have it again and again.

Impaired Sleep-Related Erections

Men usually have erections as a part of REM sleep. This parasomnia happens in men who, while they sleep, can’t keep an erect penis that would be rigid enough for sex. Impaired sleep-related erections may mean you have erectile dysfunction.

Sleep-Related Painful Erections

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Rarely, a man’s erections are painful enough that they wake up.

Irregular Heart Rhythms

Cardiac arrhythmia is the medical term for an uneven heartbeat. People who have coronary artery disease and who have lower blood oxygen because of sleep-related breathing problems may be more likely to have arrhythmias, which happen during REM sleep. Continuous positive airway pressure (CPAP) treatment may lower this risk.

REM Sleep Behavior Disorder (RBD)

REM sleep usually involves sleep paralysis, but people with this parasomnia act out dramatic or violent dreams during that sleep stage. RBD usually happens in men 50 and older. It’s different from sleepwalking and sleep terrors because a person who has RBD can be woken easily and can recall vivid details of their dream.

Sleep Bruxism (Teeth Grinding)

Bruxism is when you grind or clench your teeth severely while you sleep. It may happen along with other sleep disorders. This parasomnia can cause dental problems including unusual wear on your teeth or discomfort in your jaw muscles. Your dentist can probably give you a night guard to wear over your teeth while you sleep so they don’t grind against each other.

Sleep Enuresis (Bedwetting)

People who have this parasomnia can’t control their bladder while they sleep. It usually happens in children. There are two kinds of enuresis. In the primary form, the child has never had control of their bladder at night. It runs in families. In secondary enuresis, the person loses bladder control after previously having it. Medical conditions (for example, diabetes, urinary tract infections, and sleep apnea) or psychiatric disorders can cause enuresis.

Exploding Head Syndrome

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People who have this parasomnia think they hear a loud noise, like a bang or an explosion, just before they fall asleep or wake up. Some may think they’re having a stroke. Getting more sleep can help prevent it.

Nocturnal Paroxysmal Dystonia (NPD)

This parasomnia might be a form of epilepsy. It can cause seizure-like episodes during non-REM sleep, sometimes several times a night.

Sleep-related eating disorder (SRED)

People who have this parasomnia eat while they’re asleep, often unusual foods like raw meat or cake mix. When they wake up, they remember only fragments or nothing at all. It happens because of a mixture of wakefulness and non-REM sleep.

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