R.E.M. Behavior Disorder (RBD) is a common issue in Parkinson disease (PD), affecting at least 40% of patients (1), and may occur at any time in disease, though most commonly seen years before motor signs of tremor, stiffness (rigidity), or slowness (bradykinesia). A part of the three highly prognostic non-motor symptoms of PD – symptoms that might indicate a person is going to develop the disease, RBD is often experienced with a loss of sense of smell (hyposmia), and/or constipation (2). If one has all three of these issues without a clear explanation, the likelihood that PD will develop is high.
RBD symptoms can range from mild to severe, with behaviors characterized by sometimes aggressive or violent activity during dreams, usually in the second half of the night. People with RBD may act out dreams, writhe, twist, shout, appear to be awake or hallucinating. Sleeping bed partners may be punched, kicked, even choked by an affected person. Bed partners who try to wake an affected person may sometimes become incorporated in the dream, though my anecdotal understanding is that most patients can actually be awakened or redirected. And, usually the affected person has no recollection of the dream the next day, though those that do describe very vivid dreams. Obviously, RBD is disruptive for sleep and normal rest. RBD should not be confused with the nightmares seen in people with post-traumatic stress disorder (PTSD), night terrors, other spells seen in narcolepsy, or other parasomnias (abnormal behavior during sleep).
Though common to PD, RBD is not exclusive to this condition alone. In other words, having RBD does not guarantee a diagnosis of PD. In the general population the incidence of RBD is probably about 0.5% (3), though it is difficult to know because not everyone reports abnormal sleep behaviors, and many people who have RBD are unaware of their own symptoms. It does seem in the literature that most cases of RBD occur in people who either have, or will develop neurologic diseases. However, in some cases isolate RBD simply runs in a family, and in others it appears to be sporadic, affecting only one person. RBD can be seen in people with Lewy body dementia (LBD) or multiple system atrophy (MSA), and seems to occur in all synucleinopathies (diseases with abnormal accumulation of alpha-synuclein). RBD may rarely be seen in other neurodegenerative diseases.
In the case of PD, RBD corresponds with Braak stage II (4). This means that Lewy bodies, the pathologic hallmark of PD, have spread to a part of the brainstem called the pons, and have begun to affect control of sleep (footnote).
Under normal circumstances sleep occurs in five stages. Light sleep, or stage I, is when one first drifts into sleep and can easily be awakened because they are almost conscious. Most people do this when they doze on the couch watching a mid afternoon movie or a weekend ballgame for example. People awakened from this stage of sleep are generally very clear and quick to reorient to the world around them, easily able to say, “I guess I was asleep.” They can quickly wake and interact with others. Stage II sleep is a little bit deeper, and these people are a little harder to wake, and a little slower getting started if awakened. Stage III sleep is deeper and characterized by slowing of some of the background brain waves, which neurologists can see on an electroencephalogram (EEG, one of the tools a neurologist or sleep medicine expert might use to diagnose RBD). If awakened, these people might have trouble orienting for a few seconds. Stage IV sleep is when greater than half of the brain waves have slowed significantly, and the person is very deeply asleep, and very difficult to awaken. The classic example is illustrated by the teenager. Because teens frequently spend more time in stage IV sleep around the time we expect them to get up and get ready for school, they are sometimes very hard to wake, and very slow to get started, (and very grumpy, sorry mom). Finally, the deepest is stage V, when R.E.M. sleep occurs, (rapid eye movement sleep). During dreams the eyes dart back and forth beneath closed lids. However, under normal conditions, during this stage arms and legs are flaccid: no muscle tone, and unable to move. This is a unique time in the 24-hour cycle, because at all other times there is a baseline tone in “skeletal” muscles akin to the idle speed of an engine. During R.E.M. sleep the flaccid, non-moving limb has some advantages. Think for example, of the benefit of not making a lot of noisy movement in sleep, and how that might have protected our ancestors from the very good ears of a hungry saber-tooth tiger.
When one has RBD, sleep architecture is abnormal. A person may be in light stage I sleep and simultaneously begin to dream (stage V). One problem with this is that they may have normal muscle tone, and be quite capable of acting out dreams. As above, the dreams are often quite vivid, meaning that they seem real and feel like wakefulness. The content of the dreams is often nightmarish, or terrifying. There are frequent themes of being attacked or pursued.
There is only one FDA approved drug for RBD: clonazepam (Klonopin). The drug does help reduce some of the activity of dreams but may not have any effect on the vivid dreaming itself. In low doses that is generally helpful and tolerated. The problem with this drug is that it is a benzodiazepine, a sedative/hypnotic drug which is potentially habit-forming (addictive). The drug can also be dangerous, or even deadly if taken in high doses. There are many possible side effects of clonazepam, such as sedation, confusion, respiratory depression (trouble breathing). Further, in recent years federal government agencies including the FDA have issued many warnings about controlled substances. The state of Maine requires doctors to check the prescription monitoring program for prescription history of a patient prior to writing a prescription for the drugs. Patients are also required to sign a controlled substance agreement with the prescribing physician.
Limited studies have shown benefit with the over-the-counter supplement melatonin. It is yet to be definitively established whether or not melatonin supplementation is a good treatment for RBD-though anecdotally I have often heard of good results. Melatonin is often considered by patients to be a much safer intervention than clonazepam. This is probably true. Melatonin is a neurotransmitter produced by a part of the brain called the pineal gland. It helps to regulate the sleep-wake cycle, the circadian rhythm. Melatonin does not by itself make one drowsy but causes a sort of chain reaction which leads to sleepiness, and hopefully progression into the normal stages of sleep. Another issue with melatonin is that in spite of the fact that it is a neurotransmitter, it is considered a supplement. Supplements are not regulated by the FDA, and there have been many cases of supplements containing impurities, some even toxic. There have also been cases of supplements containing concentrations very different from what is listed on the bottle. If one is to use a supplement it is important to make sure that the company has verified through an independent testing lab that what is written on the label reflects what is contained in the bottle.
Finally, sometimes RBD is fairly benign and manifested only by disruption of a bed partner’s sleep. A simple solution is to sleep in different rooms if possible. In some cases padded bed rails to prevent falls or injury are a good idea. Some patients will move the mattress to the floor. It is also generally a good idea to avoid stimulants late in the evening. Alcohol and high doses of dopaminergic drugs used to treat the motor symptoms of PD should generally be avoided late in the evening; discuss with your doctor. In fact, one should review all meds with a doctor, as some, including antidepressants, may worsen or trigger RBD.
Footnote: The issues Lewy bodies and misfolded alpha-synuclein are addressed in multiple other articles in MPDN. For more, use the search bar for these terms.
References
- Zhang, et al. Prevalence of rapid eye movement sleep behavior disorder (RBD) in Parkinson’s disease: a meta and meta-regression analysis. Neurol Sci. 2017 Jan;38(1):163-170.
- Reichman, H. Premotor Diagnosis of Parkinson’s Disease. Neurosci. Bull. 2017, 33(5):526–534.
- Ohayon MM, Caulet M, Priest RG. Violent behavior during sleep. J Clin Psychiatry 1997; 58: 369–76.
- Braak H. Staging of brain pathology related to sporadic Parkinson’s disease. Neurobiology of Aging, 2003;24:197.