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Dreaming occurs during Rapid Eye Movement or REM sleep. With REM sleep, changes occur in brain signaling which cause reduced muscle tone in many of the body's muscles; this may be called REM sleep muscle paralysis or muscle atonia. This is considered a normal function of REM sleep. REM behavior disorder occurs when the body maintains relatively increased muscle tone during REM sleep, allowing the sleeper to move and act out their dreams. Movements may be as minor as leg twitches, but can result in very complex behavior that may cause serious injury to the individual or the bed partner. REM sleep behavior disorder is characterized by abnormal behaviors during REM sleep that may cause sleep disruption or injury; these are often manifestations of action-filled or violent dreams. Behaviors may include twitching, utterances, flailing, kicking, sitting up, and leaving the bed. At the end of an episode, an individual may awaken and become quickly alert; they may be able to provide a coherent dream story.
Adverse reactions to certain drugs or drug withdrawal can sometimes appear as RBD. However, the disorder is more common with age, and has been associated with certain neurological disorders in some cases.
The diagnosis of REM behavior disorder may be suggested by a careful evaluation but should be confirmed by a sleep study, to evaluate for other sleep disorders and to confirm abnormal muscle tone during REM sleep. In terms of management, precautions to ensure the safety of the individual and others in the sleep environment are key. Treating coexisting sleep disorders is important, and medications are often changed or started to reduce symptoms of this disorder.