Rapid Eye Movement Sleep Behaviour Disorder

Rapid eye movement sleep behaviour disorder is a condition in which people physically act out their dreams while asleep, sometimes with violent movements that can cause injury to themselves or their sleeping partners.

Table of contents

• What is REM sleep behaviour disorder?
• Symptoms and characteristics
• Who is affected?
• Causes and types
• Connection to neurodegenerative diseases
• Diagnosis
• Treatment and management
• Safety measures

What is REM sleep behaviour disorder?

Rapid eye movement sleep behaviour disorder (RBD) is a sleep disorder in which you physically and vocally act out your dreams while you are asleep, without being aware of your actions. This happens during the REM sleep stage, which is the part of sleep when most vivid dreaming occurs^[1][2].

RBD is a type of parasomnia, which means it is a sleep disorder that involves unusual and undesirable physical events or experiences that disrupt your sleep. Normally, during REM sleep, your body experiences temporary paralysis of the arms and legs, called atonia. This natural paralysis prevents you from acting out your dreams. However, in people with RBD, this protective paralysis is incomplete or absent, allowing them to move and act while dreaming^[1][4].

REM sleep typically begins about 90 minutes after you fall asleep and lasts about 10 minutes during the first cycle. You have several REM cycles throughout the night, and each cycle gets longer as the night progresses. About 20 percent of your total sleep time is spent in REM sleep, occurring primarily during the second half of the night^[1][2].

Symptoms and characteristics

The symptoms of REM sleep behaviour disorder can vary in severity from person to person. During sleep, a person with RBD may exhibit a range of behaviors while acting out their dreams^[1][2].

Physical movements can range from mild muscle twitches or limb movements to more dramatic actions. People with RBD may kick, punch, grab the air or their bed partner, arm flail, or even jump or fall out of bed. These movements often occur in response to action-filled or violent dreams, such as being chased or defending oneself from an attack^[1][2].

Vocal symptoms are also common. These can include talking, laughing, shouting, screaming, emotional outcries, or even cursing. The sounds are typically loud and emotional, and may involve vulgar language^[1][2].

Dreams experienced by people with RBD often involve violent or aggressive actions and frequently have an attack theme, such as being chased by people or animals. The symptoms tend to be more severe when a person is acting out a particularly violent nightmare^[2][4].

One important feature of RBD is that people are usually able to recall their dreams if they awaken during or shortly after an episode. When awakened, individuals are typically alert, aware, and can describe the dream content, which often matches the actions they were performing. However, they are completely unaware of their behaviors while they are asleep^[1][2].

Episodes may occur occasionally or several times during a single night. The disorder often develops gradually, with the onset being gradual or sudden, and symptoms can worsen over time^[1][2].

About 8 in 10 people with RBD experience sleep-related injuries. These injuries can affect the person with RBD themselves or their bed partner, especially when violent movements are involved. Many people only discover they have RBD when their bed partner or roommate tells them about their nighttime behavior or when they sustain an injury^[2].

Who is affected?

REM sleep behaviour disorder is relatively rare, affecting about 1% of the general population in the United States and about 2% of people aged 50 or older. However, these rates may be higher in reality, as RBD can be difficult to officially diagnose, and almost half of people with the condition do not realize they have it^[2].

RBD most commonly affects people over the age of 50. The average age when symptoms begin is 61 years. While it can also affect children and younger adults, this is rare^[2][3].

Among people over age 50, men are nine times more likely than women to have RBD. The condition shows a strong male predominance in this age group^[2][3].

Causes and types

RBD can be divided into three main categories based on its cause: idiopathic RBD, drug-induced RBD, and secondary RBD due to a medical condition^[3][4].

Idiopathic or isolated RBD happens when the condition develops spontaneously without an identifiable underlying cause. This type appears without any known reason or associated medical condition. The precise mechanism and neural structures involved in RBD are not fully understood, but based on animal and human studies, sleep-regulating areas of the brain, particularly the pontine tegmentum in the brainstem, are thought to be involved^[2][5].

Drug-induced RBD can occur in people who take certain medications. Some antidepressants can cause or worsen RBD symptoms. Selective serotonin reuptake inhibitors (SSRIs), as well as newer generation antidepressants such as venlafaxine and mirtazapine, have been identified as potential triggers. About 6% of people who take antidepressants may develop drug-induced RBD. Withdrawal from certain substances, especially alcohol or sedatives, can also trigger RBD symptoms^[2][6][11].

Secondary or symptomatic RBD happens due to an underlying medical condition. When a person has both another neurological disorder and RBD, it is considered secondary RBD. Up to 36% of people with Type 1 narcolepsy have secondary RBD. RBD can also be associated with other conditions including Guillain-Barré syndrome, limbic encephalitis, and Morvan’s syndrome^[2][4].

Connection to neurodegenerative diseases

RBD is strongly associated with certain neurodegenerative diseases, particularly those classified as alpha-synucleinopathies. These are brain disorders characterized by abnormal accumulation of a protein called alpha-synuclein^[2][3].

The three main alpha-synucleinopathies linked to RBD are Parkinson’s disease, Lewy body dementia (also called dementia with Lewy bodies), and multiple system atrophy. RBD may be associated with these neurological conditions and can appear years or even decades before other symptoms of these diseases develop^[1][2].

The connection between idiopathic RBD and these neurodegenerative diseases is remarkably strong. About 97% of people who have isolated idiopathic RBD will develop one of these three conditions within 14 years of their RBD diagnosis. Symptoms of RBD may begin decades before any other symptoms appear, often serving as the first clinical sign of an underlying neurodegenerative disorder^[2][4].

This strong predictive relationship makes RBD an important early warning sign. Because of this connection, careful monitoring and follow-up are important for people diagnosed with idiopathic RBD, even when they have no other neurological symptoms^[3].

Diagnosis

To diagnose REM sleep behaviour disorder, doctors review your medical history and symptoms. The evaluation process typically involves several components^[8][17].

Your doctor will conduct a physical and neurological examination to evaluate you for RBD and other sleep disorders. Since RBD may have symptoms similar to other sleep disorders or may occur alongside conditions such as obstructive sleep apnea or narcolepsy, a thorough assessment is necessary^[8][17].

Information from your sleeping partner is valuable for diagnosis. Your doctor may ask your bed partner whether they have seen you appear to act out your dreams while sleeping, such as punching, flailing your arms, shouting, or screaming. Your partner may be asked to fill out a questionnaire about your sleep behaviors^[8][17].

The definitive diagnosis requires confirmation by an overnight sleep study in a sleep laboratory, called a polysomnogram or polysomnography. During this test, sensors monitor your heart, lungs, and brain activity, breathing patterns, arm and leg movements, vocalizations, and blood oxygen levels while you sleep. You are typically videotaped during the study to document your behavior during REM sleep cycles. The sleep study helps confirm the diagnosis of RBD and rules out other sleep disorders^[3][6][8].

For a diagnosis of RBD, specific criteria must be met. You must have repeated episodes of arousal during sleep where you talk, make noises, or perform complex movements that often relate to dream content. You should be able to recall dreams associated with these movements or sounds if you awaken during the episode. Importantly, when you wake up from these episodes, you are completely alert and not confused or disoriented. The episodes must cause significant distress or impairment in daily life, which may include serious injury to yourself or your bed partner. Finally, the episodes cannot be better explained by the effects of medication, substance abuse, or another mental or medical disorder^[5][8][17].

Treatment and management

Treatment for REM sleep behaviour disorder focuses on several goals: reducing injurious dream-enactment behaviors, preventing injury to yourself and your bed partner, decreasing vivid or disruptive dreams, and improving sleep quality for both you and your bed partner^[12].

The two most commonly used medications for RBD are clonazepam and melatonin, although neither has been proven effective through large-scale randomized clinical trials^[9].

Clonazepam is a medication from the benzodiazepine family that has been used to treat RBD for many years. It is effective in nearly 90% of patients, with complete benefit in about 79% of patients and partial benefit in another 11%. The response usually begins within the first week, often on the first night. The initial dose is typically 0.5 mg taken at bedtime. If this is ineffective, doses can be increased to 1-2 mg. The treatment should be continued indefinitely, as violent behaviors and nightmares return promptly when the medication is stopped in almost all patients. The specific mechanism by which clonazepam works in RBD is unknown. However, in some patients, particularly elderly individuals, clonazepam may increase the risk of confusion or falls and may worsen obstructive sleep apnea^[9][11].

Melatonin has shown beneficial effects in treating RBD in several studies. The effective dose is typically 3-6 mg taken orally at bedtime. The dosage may be increased every 5-7 days up to 12 mg per day in some cases, if tolerated. Only about 36% of patients experience adverse effects, which can be resolved by decreasing the dose. The exact mechanism by which melatonin works in RBD is unclear, though it may help restore normal sleep patterns^[9][11].

For patients in whom RBD appears as an early sign of Parkinson’s disease, levodopa (a medication used to treat Parkinson’s) may be very effective in managing RBD symptoms^[11].

Other medications have been used with varying success in some patients. These include certain older antidepressants, though it is important to note that some antidepressants can actually trigger or worsen RBD. Anecdotal reports exist of responses to carbamazepine, clonidine, and L-tryptophan in patients with RBD^[11].

Safety measures

Because RBD can lead to accidental injury to yourself or your bed partner, making the sleep environment safer is an important part of managing the condition. Counseling and management should focus on injury prevention in addition to any medication treatment^[2][3].

Safety measures for the bedroom include removing dangerous objects from the sleeping area, padding the floor around the bed, and potentially using protective barriers. These modifications can help reduce the risk of injury during episodes of dream enactment^[6].

Long-term monitoring and follow-up care are important for people with RBD, particularly those with idiopathic RBD, given the strong association with future development of neurodegenerative diseases. Regular assessment by healthcare providers can help track any changes in symptoms and overall neurological health^[3][5].