What is REM Sleep Behavior Disorder?
Rapid Eye Movement (REM) sleep behavior disorder (RBD) is a condition where people act out their dreams during their REM stage of sleep. During this stage, you might notice unusual sounds, movements and extremely vivid dreams. Sometimes, this acting out can become aggressive and might lead to harmful situations for the individual or others nearby, without them even knowing it’s happening. When these individuals wake up, they often remember what they dreamt. A significant point to note is that most people who have REM sleep behavior disorder eventually show signs of neurological diseases like Parkinson’s, dementia with Lewy bodies or multisystem atrophy.
Sometimes, REM behavior disorder can also be linked with other conditions like Parkinson’s disease, narcolepsy (a condition characterized by excessive daytime sleepiness), or from taking antidepressant medications.
It’s vital for the patient to know the possibility of developing these neurological disorders in the future. Consequently, the treatment mainly focuses on preventing harm to the person suffering from REM sleep behavior disorder or their bed partner during sleep. In severe situations, they might be recommended sleep-enhancing medications like melatonin or clonazepam.
What Causes REM Sleep Behavior Disorder?
Rapid eye movement sleep behavior disorder (RBD) happens when the body can’t stop movements during REM sleep. It’s been shown that there’s a strong link between RBD and the chance of developing a certain kind of brain disorder in the future.
These brain disorders are connected with having something called alpha-synuclein in the brain cells. Alpha-synuclein is a type of protein in the human brain and when it clumps up it leads to several neurological diseases like parkinsonism (a disease that affects movement), Lewy body dementia (a type of progressive dementia), and multiple system atrophy (a rare, progressive neurological disorder).
The pons is a part of your brain that controls REM sleep. When there are problems in this part of the brain, it can lead to the development of these alpha-synuclein pathologies and also RBD. As these areas of the brain continue to degenerate or breakdown, this could be an early sign of these brain disorders before they fully develop. Brain imaging studies have found that there are abnormal levels of dopamine (a chemical responsible for transmitting signals within the brain) in patients with RBD. Therefore, medicines that increase dopamine, such as antidepressants, might make RBD worse.
Interestingly, in narcolepsy (a condition that causes excessive sleepiness) about half of the patients might show symptoms of RBD. This may be due to a lack of a hormone called orexin. Orexin helps to stabilize REM sleep and when there’s a shortage of it, it leads to a loss of muscle control during REM sleep.
Risk Factors and Frequency for REM Sleep Behavior Disorder
“Spontaneous” RBD or Rapid Eye Movement Behavior Disorder is more common in the elderly, especially men. About 1% of the general population and 2% of older people have this condition, typically at a male-to-female ratio of 9 to 1. It’s worth mentioning that RBD is often linked to several neurodegenerative disorders, meaning that it could be a warning sign of conditions such as Parkinson’s disease, multiple system atrophy, or dementia with Lewy bodies. In fact, between 76% and 81% of people with these conditions could also have RBD. A notable statistic is that close to half of the RBD patients developed a neurological disorder within 12 years.
“Secondary” RBD primarily impacts younger people and can be caused by Parkinson’s disease, narcolepsy, or the use of antidepressant medications. In terms of prevalence, about 36% of people with narcolepsy also show signs of RBD. Additionally, up to 6% of cases can display RBD symptoms due to the use of antidepressant drugs. Other less common causes of secondary RBD include vascular lesions, tumors, demyelinating disease, and autoimmune or inflammatory disorders.
Lastly, you might hear someone talk about “pseudo” RBD – this is when Obstructive Sleep Apnea (OSA) has symptoms that resemble RBD, but it’s not the same thing.
Signs and Symptoms of REM Sleep Behavior Disorder
People who have parasomnia, a sleep disorder, might not know about their symptoms. Doctors should ask these patients about their sleeping patterns, especially any movements they make during sleep. It’s important to note whether these symptoms occur during the deep (non-REM) or dream-filled (REM) stage of sleep. Even a history of epileptic activity should be considered.
In a study, it was found that only half of the patients were aware of their symptoms. These symptoms could be mild or severe and might include small movements like punching or kicking in sleep, falling out of bed, gesturing, knocking over the nightstand, or even vocalizing during an attack. A large percentage of these patients also had very vivid and intense dreams characterized by action or violence. These dreams usually occurred hand in hand with the onset of this sleep disorder. More often than not, patients might even injure themselves during sleep.
The symptoms are more likely to occur in the second half of the night, especially during the final phase of REM sleep when dream activity is at its peak. In less severe cases, patients might sleep through these occurrences, but in more severe cases, patients might wake up briefly before falling asleep again.
Besides these signs, doctors might also evaluate the patients for signs of neurodegenerative disorders, diseases that cause a progressive loss of nerve cells and affect activities like movement and mental functioning.
Testing for REM Sleep Behavior Disorder
The International Classification of Sleep Disorders has laid out specific requirements for diagnosing Rapid Eye Movement Sleep Behavior Disorder (RBD), a sleep disorder that involves acting out vivid dreams. This includes regular instances of shouting or moving during sleep, and these actions are shown to occur during the Rapid Eye Movement (REM) phase of sleep. This is typically confirmed through a sleep study, also known as polysomnography.
Another key feature of RBD is a condition where muscle tone is increased during the REM phase of sleep, meaning that the muscles may move or twitch. This is known as REM Sleep Without Atonia (RSWA). It is crucial to note that in order to diagnose RBD, there should be no signs of epilepsy or any other sleep, or physical and mental disorders. RBD is also the only parasomnia – unusual behavior during sleep – which requires a sleep study done at a sleep center for diagnosis.
The main feature that polysomnography captures in RBD is the presence of RSWA. The American Academy of Sleep Medicine sets specific criteria for defining RSWA: persistent increase in muscle activity during REM sleep or repeated sudden muscle activity bursts during REM sleep. Understanding this requires us to know what an EMG or an electromyography is. EMG is a test that checks the health of the muscles and the nerves that control them, in this case, muscles of the chin and limbs during sleep.
The recording of muscles in both the upper and lower extremities can provide a more comprehensive evaluation for RBD. However, experts are still separately studying other variations of EMG that can focus on upper extremity muscles to better detect RSWA.
It’s also important to ensure that RBD is diagnosed correctly by distinguishing it from other sleep disorders that present similar symptoms. Other parasomnias such as nightmares, sleepwalking, and sleep talking need to be ruled out, as well as disorders like sleep-related hypermotor epilepsy which may also cause movement during sleep. Most patients with this type of epilepsy, however, are often younger and unaware of their symptoms.
Treatment Options for REM Sleep Behavior Disorder
The main aim of treating sleep disorders is to make sure that patients and their sleeping partners are safe at night. This can be achieved through a combination of non-drug approaches and, if necessary, medication.
It’s important to remove dangerous objects from the patient’s environment, like guns or breakable glass objects. The patient’s sleeping partner should understand that when the patient acts out their dreams, it’s not something they’re doing on purpose. If the sleep disorder is severe, it might be safer for the patient to sleep alone. Suggestions might include using padded bed rails, or even using a sleeping bag.
Patient’s might be advised to stop taking certain types of antidepressants (SSRI and tricyclic antidepressants) as these can sometimes make the disorder worse.
In terms of medication, melatonin is now often the first choice for treating these types of sleep disorders. We don’t know exactly why it works, but doses between 6 to 18 mg can help patients to stay still during REM sleep and improve their symptoms. Patients usually start off taking 3 mg, and the dose is gradually increased if necessary until the symptoms improve.
A low dose of another medication (clonazepam) has traditionally been used to help manage symptoms. This might be helpful in reducing upsetting dreams, but again, the exact way it works is not fully understood. Some patients might experience side effects from this medication. In one study, 39% of patients experienced side effects.
What else can REM Sleep Behavior Disorder be?
When a person experiences actions during their sleep, doctors have a list of possible conditions that could be the cause. These might include:
- Rapid Eye Movement (REM) Behavior Disorder (RBD)
- Obstructive sleep apnea
- Seizures
- Nocturnal panic attacks
- Nightmares
- Disorders related to non-REM sleep such as sleepwalking, or confusion upon waking up
Usually, the doctor can figure out the differences between these disorders by asking in-depth questions about the person’s experiences. However, sometimes a special study, where the person’s sleep is monitored through video and other techniques (called a polysomnographic study), might be needed.
