REM sleep is the stage of sleep most closely associated with vivid dreaming. During normal REM sleep, the brain is highly active, but most of the body’s muscles are temporarily relaxed so that we do not physically act out what is happening in our dreams.

For people with REM sleep behavior disorder (RBD), that normal muscle relaxation doesn’t occur as it should. As a result, a person may physically or vocally act out their dreams while still asleep. Talking, shouting, kicking, punching, reaching, or making other movements can turn an ordinary night of dreaming into something that affects both the sleeper and their bed partner.

What Is REM Sleep Behavior Disorder?

REM sleep behavior disorder is a type of parasomnia, a category of sleep disorders involving unusual behaviors or experiences during sleep.

During normal REM sleep, the brain sends signals that temporarily inhibit most voluntary muscle activity. This process, sometimes called REM atonia, essentially keeps the body still while the brain experiences dreams. In RBD, that normal muscle inhibition is reduced or absent, allowing the person to physically respond to the dream.

The result can be what sleep specialists call dream enactment behavior.

Someone experiencing RBD may:

  • Talk, shout, laugh, or make other sounds while asleep
  • Move their arms or legs in response to a dream
  • Punch, kick, reach, or gesture
  • Sit up or make movements that appear purposeful
  • Occasionally leave the bed during an episode
  • Remember a vivid dream that seems to correspond with the behavior after waking

These episodes can happen occasionally or multiple times during a night, and may become more frequent or intense over time.

How Is RBD Different From a Bad Dream?

A vivid or unpleasant dream does not necessarily indicate REM sleep behavior disorder. The important distinction is what the body is doing during the dream.

Most people remain physically still during REM sleep, even when dreams are intense or emotionally charged. A person with RBD, on the other hand, may move, speak, or otherwise physically respond to the dream.

For example, someone might dream that they are running and make running movements with their legs, or dream that they are having a conversation and speak aloud. They may wake up and remember the dream clearly.

Occasional sleep talking or movement does not automatically mean someone has RBD, either. A sleep specialist looks at the pattern of behaviors, the person’s symptoms, and what is happening physiologically during sleep before making a diagnosis.

What Causes REM Behavior Disorder?

There are several circumstances that can be associated with RBD. It is more common in older adults and can occur alongside certain neurological conditions. It can also be associated with some medications, including certain antidepressants.

One reason doctors take RBD seriously is its association with certain neurological disorders, including Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy. Sometimes RBD can appear years before other neurological symptoms become noticeable.

That connection can understandably sound concerning. However, RBD is not the same thing as having one of these neurological conditions, and the presence of RBD does not mean a person will definitely develop one. It is one reason, however, that an appropriate evaluation and continued medical follow-up can be important.

Why RBD Can Be Dangerous

Dream enactment creates safety concerns for both the person experiencing RBD and anyone sleeping nearby.

A person who suddenly moves during sleep could fall out of bed or collide with furniture. A bed partner could also be unintentionally struck during an episode.

Because of this, addressing RBD is not simply about getting more restful sleep. Treatment also focuses on reducing the potential for injury.

A sleep specialist may recommend making the bedroom safer by reducing objects around the bed, moving furniture away from the sleeping area, and taking other precautions based on the person’s symptoms.

How Is REM Behavior Disorder Diagnosed?

Because several sleep disorders can cause unusual nighttime behaviors, RBD cannot be diagnosed simply by observing that someone talks or moves in their sleep.

A sleep specialist will typically begin by discussing the person’s symptoms and sleep history. A bed partner can be particularly helpful because the person experiencing the episodes may not know what they are doing while asleep.

In many cases, an overnight sleep study, or polysomnogram, is used to help confirm the diagnosis.

During a sleep study, sensors can monitor brain activity, breathing, heart activity, muscle movements, blood oxygen levels, and other aspects of sleep. Video monitoring may also be used to document behaviors occurring during REM sleep. The study can show whether the normal muscle relaxation associated with REM sleep is absent.

Can REM Behavior Disorder Be Treated?

Yes. Treatment depends on the individual, the severity of the symptoms, other health conditions, and any medications the person may be taking.

One of the first priorities is reducing the risk of injury. Changes to the sleep environment may be recommended, particularly when dream enactment involves significant movements.

A physician may also consider medication as part of treatment. Melatonin and clonazepam are among the medications that have been used to manage RBD, although they are not appropriate for everyone and should only be considered under the guidance of a healthcare professional.

The goal isn’t to eliminate dreaming, but to reduce problematic dream enactment and help the person sleep safely.

When Should You Talk to a Sleep Specialist?

Not every unusual movement during sleep is a sign of RBD. However, it is worth discussing with a healthcare provider if you or your bed partner notice a recurring pattern of:

  • Acting out dreams physically
  • Shouting or talking during vivid dreams
  • Repeated kicking, punching, or other movements during sleep
  • Falling or nearly falling out of bed
  • Sleep behaviors that are becoming more frequent or intense
  • Injuries occurring during sleep
  • Significant disruption to your or your partner’s sleep

Keeping track of what happens at night can also be useful when preparing for an appointment. A bed partner’s observations can provide valuable information, since people with RBD may not remember everything that happens while they are asleep.

Your Dreams Shouldn’t Put You at Risk

When the separation between dreaming and physical movement breaks down repeatedly, it’s worth finding out why.

REM sleep behavior disorder is a treatable sleep condition, and a proper evaluation can help distinguish it from other nighttime behaviors. If you or your bed partner are noticing repeated dream enactment, talking with a sleep specialist is a good place to start.