Parasomnias are a wide variety of disorders that revolve around sleep. Most parasomnias are dissociated sleep states which are partial arousals during the transitions between wakefulness and NREM sleep, or wakefulness and REM sleep.

NREM Parasomnias

NREM parasomnias are common during childhood but decrease in frequency with increasing age. They can be triggered in certain individuals by alcohol, sleep deprivation, physical activity, emotional stress, depression, medications, or a fevered illness. These disorders of arousal can range from confusional arousals, somnambulism, to night terrors. Other specific disorders include sleepeating, sleep sex, teeth grinding, rhythmic movement disorder, restless legs syndrome, and somniloquy.


Confusional a

Sleep terrors (night terrors)

This is the most disruptive arousal disorder since it involves loud screams and extreme panic usually resulting in the victim committing bodily harm or property damage by running around out of the bedroom or house or hitting walls. Unfortunately, all attempts to console the individual are futile and may prolong or intensify the victim’s confusioned state. Usually the victim experiences amnesia after the event but it may not be complete amnesia. Up to 3% of adults suffer from sleep terrors and exhibited behavior of this parasomnia can range from mild to extremely violent.

REM Parasomnias

REM Sleep Behavior Disorder (RBD) is the most common REM sleep parasomnia in which muscle atonia is absent. This allows the individual to act out their dreams and may result in repeated injury-- bruises, lacerations and fractures-- to themselves or others. Patients may take self-protection measures by tethering themselves to bed, using pillow barricades or sleeping in an empty room on a mattress. Demographically, 90% of RBD patients are males, and most are older than 50 years of age.

Acute RBD

Occurs mostly as a result of a side-effect in prescribed medication- usually antidepressants.

Chronic RBD

Is idiopathic or associated with neurological disorders. There is a growing association of chronic RBD with neurodegenerative disorders – Parkinson’s disease, multiple system atrophy (MSA) or dementia-- as an early indicator of these conditions by as much as 10 years. Patients with narcolepsy also are more likely to develop RBD.

See also


  • Mahowald & Schenck. Insights from studying human sleep disorders. Nature (2005); 437(7063):1279-85.
  • Bassetti et al., Lancet (2000); 356: 484–485


Further reading

  • Siegel, Ronald (1992). Fire in the Brain: Clinical Tales of Hallucination.
  • Warren, Jeff (2007). The Head Trip: Adventures on the Wheel of Consciousness.

External links

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