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. The patient is usually easy to arouse, and will recall events the next day.

Risk Factors
  • Traumatic brain injuries, farming and pesticides exposure, and lower education are risk factors.[1]
  • 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.
Prognosis
Prevalence
  • The prevalence of REM sleep behaviour disorder is approximately 0.5% in the general population.
    • It is more common in males than females.
  • 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 clinical question: “Have you ever been told (or suspected yourself) that you seem to 'act out your dreams' while asleep (e.g. - punching, flailing your arms in the air, making running movements)?” is highly sensitive and specific for REM sleep behaviour disorder (sensitivity 93.8%, specificity 87.2%)[3]

The onset of REM sleep behaviour disorder may be gradual or rapid, and the course is usually progressive. The disorder is thought to be due to loss of spinal inhibition in REM. It is aggravated by SSRI use, and typically occurs in the last 1/3 of sleep.

  • There is a very high association with the later appearance of an underlying neurodegenerative disorder, in particular synucleinopathies.
  • REM sleep behaviour disorder is highly prevalent in individuals with Parkinson's disease (30 to 50%), multiple system atrophy (80 to 95%), and Lewy body dementia (50 to 80%). REM sleep behaviour disorder associated with neurodegenerative disorders may actually improve as the underlying neurodegenerative disorder progresses.[4]
  • REM sleep behaviour disorder often predates any other sign of these disorders by many years (often more than a decade).

Polysomnography shows:

  • Increased tonic and/or phasic electromyographic activity during REM sleep (normally expect muscle atonia)
  • The increased muscle activity variably affects different muscle groups (submentalis, bilateral extensor digitorum, and bilateral anterior tibialis muscle groups)
  • Frequent periodic and aperiodic extremity electromyography activity during non-REM (NREM) sleep, termed REM sleep without atonia

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.

  • Placing padding on floors, safety planning with bed partners to avoid injuries are important first steps.
  • High dose melatonin is now favoured over the use of benzodiazepines such as clonazepam.[5][6]
  • In the past, low dose benzodiazepines such as clonazepam (generally 0.5mg qHS) used to be commonly prescribed.[7][8]
    • However, the risks of respiratory depression, falls, cognitive impairment, and dependence risks are of considerable concern, and thus melatonin is now favoured.
    • There should also be caution in prescribing this medication in individuals with obstructive sleep apnea, gait disorders, or dementia.

Mnemonic

You can REMember events (i.e. - no confusion, no amnesia) in REM parasomnias!

Comparison of Parasomnias

Parasomnia Type Stage of Arousal Time of Night EEG during event EMG during event Unresponsive during event Autonomic activity Anmesia Confusion post-episode Family history of parasomnias
Confusional Arousal NREM NREM Stage 2-4 Anytime N/A Low Yes Low Yes Yes Yes
Sleepwalking NREM NREM Stage 3-4 First 2 hours Mixed Low Yes Low Yes Yes Yes
Sleep terrors NREM NREM Stage 3-4 First 2 hours Mixed Low Yes High Yes Yes Yes
REM sleep behaviour disorder REM REM Anytime (but more likely later half) Characteristic of REM High Yes High No No (can remember the dreams!) No
Nightmare disorder REM REM Anytime N/A N/A Yes High No No (can remember the dreams!) No

REM Sleep Behavior Disorder (RBD) Guidelines

Guideline Location Year PDF Website
Canadian Medical Association Journal (CMAJ): Parasomnias Canada 2014 - Link
National Institute for Health and Care Excellence (NICE) UK 2017 - Link
American Academy of Sleep Medicine (AASM) USA 2010 - Link