People with REM Sleep Behavior Disorder (RBD) tend to speak and shout and also move vigorously or violently during REM sleep. These episodes of abnormal movements may result in injury to the patient or a bed partner. If the patient awakens during these episodes, the patient reports that the specifics of the observed movements correspond to the violent events taking place in a dream.

Muscles, except those that mediate breathing and movement of the eyes, fingers and toes, are paralyzed during normal REM sleep. Electrical activity and oxygen consumption of the brain continues to the same degree as during wakefulness.

In some cases, it is sufficient to make the diagnosis of REM sleep behavior based on the patient's history. In other cases, it is difficult to distinguish the symptoms from those of sleep walking, sleep talking, seizures or sleep terrors. For these difficult cases, it is sometimes helpful to do an overnight sleep recording, known as a polysomnogram (PSG). An episode of REM sleep behavior disorder may be recorded during the polysomnogram or there may be one or more awakenings directly from Stage REM sleep.

Treatment of REM sleep behavior disorder includes prescription of medications to deepen sleep and/or to suppress Stage REM sleep.

There is a risk of development of Parkinson's disease in those with RBD; the exact risk and circumstances should be discussed with the physician.