What Is REM Sleep Without Atonia: Symptoms and Causes

Rapid eye movement (REM) sleep is a stage characterized by vivid dreams and brain activity that resembles wakefulness. A feature of normal REM sleep is atonia, a state of temporary muscle paralysis that prevents individuals from physically acting out their dreams. REM sleep without atonia, or REM Sleep Behavior Disorder (RBD), occurs when this paralysis is absent or incomplete. This allows the person to physically and vocally enact their dreams, which are often intense and action-filled.

Identifying the Symptoms

The primary signs of REM Sleep Behavior Disorder are physical movements and vocalizations corresponding to the content of a person’s dreams, which are often vivid, unpleasant, or violent. Behaviors range from simple muscle twitches to complex actions like punching, kicking, or jumping out of bed. Vocalizations can include talking, shouting, laughing, or cursing.

A person having an RBD episode is not conscious of their actions. If awakened, they are alert and can often recall the dream they were having. This is different from sleepwalking, which occurs during deep non-REM sleep, where an individual is confused upon waking and has no dream to report. RBD episodes tend to happen at least 90 minutes after falling asleep, aligning with the body’s sleep cycles.

Underlying Causes and Associated Conditions

REM Sleep Behavior Disorder stems from a malfunction in the brainstem’s neural pathways. Specifically, the part of the brainstem known as the pons, which is responsible for inducing muscle atonia during REM sleep, fails to function correctly. This failure of temporary paralysis allows for physical dream enactment.

A strong association exists between RBD and certain neurodegenerative diseases like Parkinson’s disease, Lewy body dementia, and multiple system atrophy. These conditions are characterized by abnormal protein deposits in the brain. The onset of RBD can be an early indicator of these diseases, sometimes appearing years before other symptoms become apparent.

Not all RBD cases predict future neurodegenerative disease, as the disorder can be triggered by other factors. Certain medications, such as some antidepressants, can cause RBD symptoms. Withdrawal from alcohol or sedative medications can also lead to the condition. In these instances, the disorder may be temporary and resolve once the trigger is removed.

The Diagnostic Process

Diagnosing REM Sleep Behavior Disorder begins with a clinical evaluation of the patient’s medical history and symptoms. Input from a bed partner or family member who has witnessed the sleep behaviors is important. Their observations of actions like punching or shouting during sleep provide initial evidence for a diagnosis.

The standard for confirming RBD is an overnight, in-lab sleep study called a polysomnogram. During this test, sensors monitor the patient’s brain wave activity (EEG), eye movements (EOG), heart rate, breathing, and muscle tone (EMG).

The polysomnogram allows specialists to observe the patient’s sleep stages. For an RBD diagnosis, the finding is the confirmation of REM sleep without atonia. This is visible as persistent electrical activity in the muscles during the REM stage, which helps rule out other sleep disorders.

Management and Safety Strategies

Once diagnosed, management of REM Sleep Behavior Disorder focuses on two areas: medical treatment to control symptoms and strategies for a safe sleep environment. The goal is to reduce the episodes’ frequency and intensity while preventing injury to the individual or their bed partner.

Medical intervention involves specific medications. Melatonin, a dietary supplement, is often recommended and can be effective with few side effects. Clonazepam is another prescription medication used to treat RBD, but it can cause side effects like daytime drowsiness and requires caution with conditions like obstructive sleep apnea.

Creating a safe bedroom environment is a component of managing RBD. This involves making modifications to prevent injuries from acting out dreams. Padding the floor around the bed can cushion falls, and moving sharp or heavy objects like nightstands away from the bedside is important. Removing any other dangerous items from the room is also a necessary precaution.