Rapid eye movement sleep behavior disorder Rapid eye movement sleep behavior disorder Rapid eye movement sleep behavior disorder (RBD) is a sleep disorder (more specifically a parasomnia) in which people act out their dreams. It involves abnormal behavior during the sleep phase with rapid eye movement (REM) sleep. The major feature of RBD is loss of muscle atonia (i.e., the loss of paralysis) during otherwise intact REM sleep (during which paralysis is not only normal but necessary). REM sleep is the stage of sleep in which most vivid dreaming occurs. The loss of motor inhibition leads to a wide spectrum of behavioral release during sleep. This
Rapid eye movement sleep a brief awakening. This does not occur for either cats or humans, although humans are more likely to wake from REM sleep than from NREM sleep. Snyder hypothesized that REM sleep activates an animal periodically, to scan the environment for possible predators. This hypothesis does not explain the muscle paralysis of REM sleep; however, a logical analysis might suggest that the muscle paralysis exists to prevent the animal from fully waking up unnecessarily, and allowing it to return easily to deeper sleep. Jim Horne, a sleep researcher at Loughborough University, has suggested that REM in modern humans compensates for the