REM behaviour disorder (RBD) is a parasomnia in which the subjects act out dreams with physical movements that are considered to be the equivalent of what they are doing in their dreams. Dreams often include events that trigger wild motions and flailing of limbs that can be harmful to a bed partner, or the sufferer themselves.
REM refers to Rapid Eye Movement, which is the last stage of sleep, and also commonly called the dream sleep stage. REM sleep is when most dreams take place. During this phase of sleep, most people will experience muscle atonia, or paralysis, in which the body has effectively shut down. People with RBD do not experience muscle atonia during REM sleep, which accounts for their ability to perform physical actions during this stage of sleep. REM sleep typically takes 1 to 1 ½ hours to set in, so episodes of RBD will not commence until this time has elapsed. Some people may have multiple episodes during a night, and others may only experience them once every week or longer.
RBD is not to be confused with other forms of parasomnia such as sleepwalking, sleep terrors, nocturnal seizures or periodic limb movements, though people with RBD may suffer some of the above sleep disorders as well. RBD occurs exclusively in the phase of deep sleep, while these other sleep disorders primarily occur in earlier sleep phases. RBD episodes will rarely include walking around, and do not include eating or drinking, which is another way of differentiating them from sleepwalking. Polysomnogram tests are crucial for determining which sleep disorder is at play.
Episodes of RBD often begin with only mild activity that may go unnoticed for a long time, and RBD is often left unnoticed or undiagnosed for years. Over time episodes will get worse, and could contain acting out of violent events that may include motions of punching, kicking, wild flailing, grabbing and even leaping or jumping around in some cases.
RBD is most common in older men, and under 1% of people suffer from it. It is much less prevalent in women, with as few as 0.1% of women having it. There is some debate over whether this is the result of less reported cases involving women, who are much less likely to seriously harm a bed partner during sleep, or if there is actually such a wide gulf in the prevalence of the disease, either through genetics or androgyny. It most often appears in men over the age of 50, with the average age of first signs being around 60 years of age.
The presence of neurological disorders have shown to increase the risk of RBD by as much as 50%, including parkinson’s disease and multiple system atrophy, and RBD in people without these disorders could indicate an increased risk of developing them in the future. Other factors that influence the intensity of REM sleep may also play a role in RBD rates, including alcohol consumption or withdrawal, strokes, brain tumours, sleep deprivation, and medication use. In the case of alcohol or medication use, RBD may only be acute, rather than chronic as it is in most other cases.
RBD will likely get worse over time, so early detection and treatment is helpful. If RBD is suspected, a sleep doctor should be consulted, and an overnight sleep study set up. The polysomnogram not only charts any physical movements made during sleep, it also charts brain waves and can accurately monitor the stage of sleep a subject is in at all times, which is useful for coming to a diagnosis of RBD. RBD may also indicate the presence of other sleep disorders such as narcolepsy and periodic limb movement, and the polysomnogram may be able detect the presence of all of these in just one night. Neurological tests may also be appropriate to rule out any other disorders.
If alcohol or medication use is the likely cause of the episodes, a simple switch in medications, and/or abstaining from alcohol should quickly clear up the number of episodes of RBD. In cases of withdrawal symptoms, it may be necessary for the bed partner to sleep in a separate bed or room until the symptoms regress, and episodes of RBD tail off.
The most common treatment for chronic RBD is clonazapam, an anti-convulsant drug. This drug suppresses muscle activity, and largely prevents any actions from taking place. Additional precaution should be taking regarding bedroom safety for those with chronic RBD. Keeping objects away from the subject’s side of the bed, such as night tables, lamps, clocks, etc. is a good step. An additional step could be to put a protective device over the subject’s hands, both to prevent damage to them, and to limit damage from them to other things, including a bed partner.
Reviewed September, 2007