What is REM Sleep Behaviour Disorder (RBD)? Symptoms & Causes

Rapid eye movement (REM) sleep is the fourth stage of sleep, taking place about 90 minutes after a person drifts off. In typical REM sleep, most of the body’s muscles enter a state of temporary paralysis known as muscle atonia. However, in REM sleep behaviour disorder (RBD), this atonia does not occur. This means people with RBD can physically respond to their dreams as they sleep, affecting sleep quality and putting themselves and their partners at risk. While there is no cure, symptoms can be managed with treatment.

Common Symptoms of REM Sleep Behaviour Disorder

RBD is part of a group of sleep disorders known as parasomnias conditions involving unwanted, involuntary behaviours during sleep or partial awakenings.

Symptoms of RBD may include:

  • Dream Enactment: Movements in response to vivid dreams, such as punching, kicking, flailing, or jumping out of bed.
  • Vocalisations: Talking, shouting, laughing, or making other vocal sounds while asleep.
  • Recall: Being able to remember the dream clearly if awoken during an episode.
  • Timing: Behaviours generally happen in the second half of the night, closer to awakening in the morning, when REM sleep is most frequent.

Individuals with RBD are unaware of their actions during sleep. Many find out about their condition through a bed partner or after an injury occurs during an episode.

RBD vs. Sleepwalking: Key Differences

RBD is often confused with sleepwalking because they share symptoms like wandering and talking. However, they are distinct conditions:

  • Sleepwalking occurs during slow wave (deep) sleep stages.
  • RBD happens exclusively during REM sleep.

What Causes RBD? Isolated vs. Symptomatic Types

RBD affects approximately 1% of the general population and is most common in people over age 50. The condition is categorized by its underlying cause:

Isolated RBD

This form develops on its own. While the exact cause is unknown, research suggests it involves disturbances to neural pathways that normally restrict muscle activity during REM sleep. Growing evidence indicates that isolated RBD can be an early warning sign of neurological conditions like Parkinson’s disease and dementia with Lewy bodies.

Symptomatic & Drug Induced RBD

This form occurs as a result of other conditions or triggers:

  • Neurologic Disorders: Stroke, multiple system atrophy, epilepsy, and multiple sclerosis are linked to higher rates of RBD.
  • Narcolepsy: Individuals with type 1 narcolepsy have lower levels of orexin, a brain chemical that regulates sleep, which can prevent stable REM cycles.
  • Medications: Certain antidepressants can trigger drug induced RBD by creating imbalances in brain chemicals like dopamine and serotonin.

Diagnosing and Managing RBD Safely

The onset of RBD can be sudden or gradual, and it tends to worsen over time. Diagnosing the disorder involves a medical exam, a review of medications, and sleep studies (polysomnography) to eliminate other disorders.

Safety Measures and Treatment

  • Create a Safer Environment: Keep heavy or sharp objects away from the bed and take measures to prevent falling out of bed.
  • Regular Monitoring: Those with isolated RBD should visit their healthcare provider regularly to monitor for signs of associated neurological conditions.
  • Medication: In severe cases, a doctor may prescribe medication to help manage and reduce the frequency of symptoms.

It is important to consult a doctor if symptoms of REM sleep behaviour disorder arise or worsen.