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What Are Parasomnias?

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By Editorial Team

3 min read

Reviewed by: HU Medical Review Board | Last reviewed: June 2020

Of the more than 80 different sleep disorders, parasomnias are some of the most common, especially in children. Parasomnias are a group of sleep disorders in which the person has unwanted experiences while falling asleep, during sleep, or when waking up. Sleepwalking and night terrors are the most well-known parasomnias.1-3

Parasomnias were once considered a sign of mental illness.2

Who gets parasomnias?

Most parasomnias are more common in children than in adults. However, men over 50 are most likely to develop REM sleep behavior disorder.2-3

Types of parasomnias

There are 2 categories of parasomnias:2

  • Disorders of arousal (non-REM parasomnias)
  • REM sleep parasomnias

Disorders of arousal

Disorders of arousal usually take place during the first third of the night during deep sleep. While asleep, people may appear to be partially awake. People with disorders of arousal wake up feeling disoriented and confused and do not remember their dreams or what they were doing. Sleepwalking, confusional arousals, sleep terrors, and sleep eating are examples of disorders of arousal.2

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REM sleep parasomnias

REM sleep parasomnias take place during late night or early morning, during REM sleep. People in the middle of REM sleep parasomnias appear to be asleep. People who wake up during a REM parasomnia are often alert and can recall their dreams or what they were doing. REM sleep behavior disorder, nightmares, and sleep hallucinations are examples of REM sleep parasomnias.2

Within these 2 categories, many different types of behaviors can happen during sleep, including:3

  • Confusional arousal - Confusion, not knowing where you are, or what you are doing when you wake up. This tends to happen during the first third of the night. It is also called sleep drunkenness.
  • Sleepwalking - Walking around while asleep. These people often appear to be awake but it is hard to actually wake them up. The walking may stop suddenly and if the person awakes, they will be confused and not know how they got where they are. Sleepwalking is also called somnambulism.
  • Sleep terrors - Extreme dreams that wake the person in intense fear, with or without memory of the dream. These people often awake with a piercing scream, and thrash, kick, or shout. They may injure themselves or others in trying to escape or fight. Also called night terrors.
  • REM sleep behavior disorder - Acting out vivid dreams while asleep. These people may kick, punch, or flail and hurt themselves or a bed partner. Episodes tend to get worse over time. It is usually easy to wake them up, unlike with sleepwalking or sleep terrors.
  • Sleep eating - Binge eating or drinking strange, high-calorie foods while partly awake. These people may have no memory or little memory of their behavior. Most eat every night, and some more than once a night.
  • Sleep paralysis - Unable to move the body when falling asleep or waking up. Lasts from a few seconds to a few minutes. The person cannot speak or move but can breathe normally.
  • Sleep hallucinations - Imagined events that seem real. These hallucinations are usually visual but may include sound, touch, taste, smell, and motion. These usually occur when the person is just falling asleep or just about to wake up. If this occurs in the daytime, it may be a sign of narcolepsy.
  • Nightmares - Bad dreams wake the person and happen so often the person begins to fear or be anxious about going to sleep. Unlike sleep terrors, these dreams can be remembered when the person awakes.
  • Bedwetting - Failing to wake up when the bladder is full. It is only considered a sleep disorder in someone over 5 years old. Bedwetting is also called sleep enuresis.
  • Exploding head syndrome - Hearing a loud noise that is not really there just before falling asleep or waking up. People with these normally painless attacks often think they are having a stroke. Attacks may occur over several nights and then subside for days or weeks.
  • Sleep talking - Usually harmless though it may disturb a sleep partner. Talking out loud during sleep may be fairly loud and nonsensical. It is also called somniloquy. Some adults may act inappropriately, hostile, or aggressive during these episodes. It is often hard to wake someone up in the middle of one of these episodes.

Parasomnias in childhood

Parasomnias seem to be a fairly normal part of a child’s early sleep patterns. This includes sleepwalking, nightmares, and bedwetting after age 5. Half of all children talk in their sleep while only 5 percent of adults do.

Other types of sleep disorders include:

InsomniaSleep-related breathing disorders such as sleep apneaSleep-related movement disorders such as restless legs syndrome and periodic limb movement disorderHypersomnias such as narcolepsyCircadian rhythm disorders such as shift-work disorder