A major breakthrough in studying dreams came in 1953, when researchers began

The major breakthrough in the study of dreams came in 1953 when researchers Eugene Aserinsky and Nathaniel Kleitman studied and discovered what happens when a person falls asleep. They found that the body enters into a psycho-physiological state in intervals of 90 minute cycles during sleep. This physiological state consists of heightened brain activity, Rapid Eye Movement (REM), increased breathing, a temporary paralysis of the body and genital engorgement. Through experiments, they confirmed that these physiological observations were the result of the person being in the dream state.