Rapid eye movement sleep in the brains of sleeping cats. In 1944, Ohlmeyer reported 90-minute ultradian sleep cycles involving male erections lasting for 25 minutes. At University of Chicago in 1952, Eugene Aserinsky, Nathaniel Kleitman, and William C. Dement, discovered phases of rapid eye movement during sleep, and connected these to dreaming. Their article was published September 10, 1953. Aserinsky, then Kleitman, first observed the eye movements and accompanying neuroelectrical activity in their own children. William Dement advanced the study of REM deprivation, with experiments in which subjects were awoken every time their EEG indicated the beginning of REM sleep. He published "The Effect
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