What they are, who they affect, their distinct types, and which treatments can help

“Parasomnia” is a catchall term for unusual behaviors1 that people experience prior to falling asleep, while asleep, or during the arousal period between sleep and wakefulness. These behaviors vary considerably in terms of characteristics, severity, and frequency.

Historically, parasomnias were considered a definitive sign of psychopathology, but some contemporary researchers argue these phenomena occur as the brain transitions in and out of sleep2, as well as between rapid eye movement (REM) and non-rapid eye movement (NREM) sleep cycles. Parasomnias are more common in children than adults, but these behaviors have been recorded across different age groups.

Types of Parasomnia

While each parasomnia carries distinct symptoms and diagnostic criteria, these behaviors can be categorized into three general groups: NREM-related, REM-related, and “other.”

NREM-Related Parasomnias

Non-rapid eye movement sleep constitutes the first stage of one’s sleep cycle, known as “shallow” sleep, and the second, third, and fourth stages, during which the sleep becomes gradually deeper. Collectively, these stages usually last about 90 minutes.

The most common NREM-related parasomnias are known as disorders of arousal. These parasomnias are characterized by recurrent episodes of incomplete awakening, limited responsiveness to other people attempting to intervene or redirect the sleeper, and limited cognition during the episode. Most people who experience disorders of arousal have little to no memory of their episodes. These disorders include:

  • Confusional arousals: The sleeper exhibits mental confusion or confused behavior in bed. Most people who experience confusional arousals display very little autonomic arousal in the form of mydriasis (dilated pupils), tachycardia (accelerated heartbeat), tachypnea (accelerated breathing), or perspiration. Confusional arousals are also known as Elpenor syndrome.
  • Sleepwalking: Also known as somnambulism, sleepwalking occurs when people get out of bed while still asleep but exhibit limited awareness or responsiveness to their surroundings. They may exhibit other complex behaviors such as sorting clothes. Sleepwalking can also lead to injuries if the individual loses their balance or collides with other objects.
  • Night terrors (or sleep terrors): People who experience night terrors often scream in their sleep, though most are not responsive to outside stimuli and will have no recollection of the source for their terror upon waking. Most night terror episodes last between 30 seconds and three minutes.
  • Sleep-related sexual abnormal behaviors: Known colloquially as “sexsomnia,” this specific parasomnia subtype is characterized by unusual sexual behaviors during sleep, such as aggressive masturbation, initiation of sexual intercourse, and sexual noises.  read more