In 1913, French Scientist Henri Pieron authored a book entitled “Le probleme physiologique du sommeil,” which was the first text to examine sleep from a physiological perspective. This work is usually regarded as the beginning of the modern approach to sleep research. Dr. Nathaniel Kleitman, now known as the “Father of American sleep research,” began work in Chicago in the 1920s questioning the regulation of sleep and wakefulness and of circadian rhythms. Kleitman’s crucial work included studies of sleep characteristics in different populations and the effect of sleep deprivation. In 1953 he and one of his students, Dr. Eugene Aserinsky, made the landmark discovery of rapid eye movement (REM) during sleep.