Normal sleep has 2 distinct states: non–rapid eye movement (NREM) and rapid eye movement (REM) sleep. NREM sleep is divided into 3 stages (N1, N2, N3). During REM sleep, rapid eye movements occur, breathing becomes irregular, blood pressure rises, and there is loss of muscle tone (paralysis). However, the brain is highly active, and the electrical activity recorded in the brain by EEG during REM sleep is similar to that recorded during wakefulness. REM sleep is usually associated with vivid dreaming. Normally REM sleep accounts for 20-25% of the sleep period, and this percentage remains fairly stable throughout the human life span.
In a person with REM behavior disorder (RBD), the paralysis that normally occurs during REM sleep is incomplete or absent, allowing the person to “act out” his or her dreams. RBD is characterized by the acting out of dreams that are vivid, intense, and violent. Dream-enacting behaviors include talking, yelling, punching, kicking, sitting, jumping from bed, arm flailing, and grabbing. An acute form may occur during withdrawal from alcohol or sedative-hypnotic drugs.
RBD is usually seen in middle-aged to elderly people. It is 9 times more common in men than in women.
What causes RBD?
The exact cause of REM behavior disorder (RBD) is unknown, although the disorder may occur in association with various degenerative neurological conditions such as Parkinson’s disease, multisystem atrophy, diffuse Lewy body dementia, and Shy-Drager syndrome. In 55% of persons the cause is unknown, and in 45%, the cause is associated with alcohol or sedative-hypnotic withdrawal, tricyclic antidepressant (such as imipramine), or serotonin reuptake inhibitor use (such as fluoxetine, sertraline, or paroxetine) or other types of antidepressants (mirtazapine).
What are the symptoms of RBD?
Patients ”Act Out” their dreams causing harm to themselves and/or bed partners. Their sleep is disturbed only if they are awakened by a frightened spouse or they fall out of bed. Patients and their bed partners have had serious injuries and some deaths have been attributed to this disorder.
Who is affected?
RBD often precedes the development of neurodegenerative disease such as Parkinson’s Disease by several years. In one study, 60% of patients diagnosed with RBD subsequently developed Parkinson’s disease with a lag time that can be as long as 12-13 years from the onset of RBD symptoms. The prevalence of RBD is increased in persons with Parkinson’s disease and in multisystem atrophy where it is observed in 69% of these patients. The relationship between RBD and Parkinson’s disease is complex and not yet well-understood, but it behooves a patient with RBD to be followed closely by a neurologist.
How is RBD diagnosed?
Often, the patient gives a history of acting out dreams and this gives the sleep specialist a strong suspicion of RBD, but the American Academy of Sleep Medicine strongly recommends an overnight sleep study where decreased muscle tone during REM may be observed as well as frank dream enactment.
How RBD is treated?
The good news is that this disorder is easily treated in 90% of cases with a low dose benzodiazepine such as Clonazepam. Patients often get relief after one night of treatment and most within one week.