Rapid Eye Movement (REM) Sleep Behaviour Disorder

Rapid eye movement (REM) sleep behaviour disorder is a sleep disorder characterized by repeated episodes of arousal, often associated with vocalizations and/or complex motor behaviours arising during REM sleep. These behaviours often reflect motor responses to the content of action-filled or violent dreams of being attacked or trying to escape from a threatening situation, called “dream enacting behaviours”. The vocalizations are often loud, emotion-filled, and profane. These behaviours may be very bothersome to the individual and the bed partner and may result in significant injury.

Risk Factors

REM sleep behaviour disorder overwhelmingly affects males older than 50 years, but increasingly this disorder is being identified in females and in younger individuals. Symptoms in young individuals, particularly young females, should raise the possibility of narcolepsy or medication-induced REM sleep behaviour disorder.

Prevalence

The prevalence of REM sleep behaviour disorder is approximately 0.5% in the general population. Prevalence in patients with psychiatric disorders may be greater, possibly related to medications prescribed for the psychiatric disorder.

Criterion A

Repeated episodes of arousal during sleep associated with vocalization and/or complex motor behaviours.

Criterion B

These behaviours arise during rapid eye movement (REM) sleep and therefore usually occur more than 90 minutes after sleep onset, are more frequent during the later portions of the sleep period, and uncommonly occur during daytime naps.

Criterion C

Upon awakening from these episodes, the individual is completely awake, alert, and not confused or disoriented.

Criterion D

Either of the following:

  1. REM sleep without atonia on polysomnographic recording
  2. A history suggestive of REM sleep behaviour disorder and an established synucleinopathy diagnosis (e.g., Parkinson’s disease, multiple system atrophy).
Criterion E

The behaviours cause clinically significant distress or impairment in social, occupational, or other important areas of functioning (which may include injury to self or the bed partner).

Criterion F

The disturbance is not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication) or another medical condition.

Criterion G

Coexisting mental and medical disorders do not explain the episodes.

The onset of REM sleep behaviour disorder may be gradual or rapid, and the course is usually progressive.

Neurodegenerative disorders

There is a very high association with the later appearance of an underlying neurodegenerative disorder, most notably one of the synucleinopathies (Parkinson's disease, multiple system atrophy, or major or mild neurocognitive disorder with Lewy bodies). REM sleep behaviour disorder associated with neurodegenerative disorders may improve as the underlying neurodegenerative disorder progresses. Based on findings from individuals presenting to sleep clinics, most individuals (>50%) with initially “'idiopathic” REM sleep behaviour disorder will eventually develop a neurodegenerative disease—most notably, one of the synucleinopathies (Parkinson's disease, multiple system atrophy, or major or mild neurocognitive disorder with Lewy bodies). REM sleep behaviour disorder often predates any other sign of these disorders by many years (often more than a decade).

Polysomnography

Associated laboratory findings from polysomnography indicate increased tonic and/or phasic electromyographic activity during REM sleep that is normally associated with muscle atonia. The increased muscle activity variably affects different muscle groups, mandating more extensive electromyographic monitoring than is employed in conventional sleep studies. For this reason, it is suggested that electromyographic monitoring include the submentalis, bilateral extensor digitorum, and bilateral anterior tibialis muscle groups. Continuous video monitoring is mandatory. Other polysomnographic findings may include very frequent periodic and aperiodic extremity electromyography activity during non-REM (NREM) sleep. This polysomnography observation, termed REM sleep without atonia, is present in virtually all cases of REM sleep behaviour disorder but may also be an asymptomatic polysomnographic finding.

Clinical dream-enacting behaviours coupled with the polysomnographic finding of REM without atonia is necessary for the diagnosis of REM sleep behaviour disorder. REM sleep without atonia without a clinical history of dream-enacting behaviours is simply an asymptomatic polysomnographic observation. It is not known whether isolated REM sleep without atonia is a precursor to REM sleep behaviour disorder.

  • Narcolepsy: REM sleep behavior disorder is present concurrently in approximately 30% of patients with narcolepsy.
  • Other parasomnias
  • Nocturnal seizures
  • Obstructive sleep apnea
  • Other specified dissociative disorder (sleep-related psychogenic dissociative disorder)
  • Malingering
  • Symptoms in young individuals, particularly young females, should raise the possibility of narcolepsy or medication-induced REM sleep behaviour disorder
  • Medication-induced REM Sleep Behaviour Disorder: many widely prescribed medications, including tricyclic antidepressants, selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and beta-blockers, may result in polysomnographic evidence of REM sleep without atonia and in frank REM sleep behaviour disorder. It is not known whether the medications per se result in REM sleep behaviour disorder or they unmask an underlying predisposition.

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