Rapid eye movement behavior disorder (RBD)
Rapid eye movement sleep behaviour disorder (RBD) is a sleep disorder (more specifically a parasomnia) that involves abnormal behavior during the sleep phase with rapid eye movement (REM sleep). It was first described in 1986.
The major and arguably only abnormal feature of RBD is loss of muscle atonia (paralysis) during otherwise intact REM sleep. This is the stage of sleep in which most vivid dreaming occurs. The loss of motor inhibition leads to a wide spectrum of behavioural release during sleep. This extends from simple limb twitches to more complex integrated movement, in which sufferers appear to be unconsciously acting out their dreams. These behaviours can be violent in nature and in some cases will result in injury to either the patient or their bed partner.