Nathaniel Kleitman, PhD, 1895-1999

August 16, 1999

Nathaniel Kleitman, PhD, professor emeritus in the department of physiology at the University of Chicago--pioneer in sleep research and the co-discoverer of REM sleep--died in Los Angeles, California on August 13, 1999 at the age of 104.

The world's first scholar to concentrate entirely on sleep, Kleitman is universally recognized as the father of sleep research. Before him, few scientists had systematically investigated the intricacies of sleep, which had previously been dismissed as a state of quiescence. After Kleitman and colleagues demonstrated in the 1950's that sleep was a dynamic and varied process, there was an explosion of interest in sleep, in sleep research and, subsequently, in the treatment of sleep disorders.

"Nathaniel Kleitman was the first scholar of sleep," said Allan Rechtschaffen, PhD, professor emeritus of psychiatry at the University of Chicago and former director of the University's Sleep Research Laboratory. "He was the first to take a deep, complete, absorbing interest in sleep; the first to compile the existing knowledge of sleep into a unified text; and with his students, the first to map out the multiple discreet stages of sleep."

"Kleitman put sleep on the map," said William Dement, MD, PhD, director of the Sleep Disorders Clinic at Stanford and one of Kleitman's students. "He never really got the spotlight because he chose to specialize in an area that was seen as a backwater at the time, but there are now nearly 6 billion people on earth. They all spend one-third of their lives asleep, and for that rather substantial side of humanity, he stands alone as the major figure. Without Kleitman getting the rest of us interested in sleep research, millions of lives would have been adversely affected."

Kleitman joined the University of Chicago faculty in 1925 and established the world's first sleep laboratory, filled with measuring devices designed and built by himself and his students. In 1939, he published the first major textbook on sleep, "Sleep and Wakefulness," which rapidly became the "Bible" of sleep researchers everywhere. It was replaced only by his revised and enlarged edition published in 1963.

In September 1953, as a result of work in his laboratory, Kleitman and one of his students, the late Eugene Aserinsky, reported the discovery of rapid eye movements (REMs) during sleep and suggested the association of these eye movements with dreaming. This discovery is often described as the beginning of modern sleep research, for it demonstrated that there were at least two major kinds of sleep and that sleep included active brain processes.

In the 1950s Kleitman and his student William Dement (who went on to open the first sleep clinic at Stanford University) refined the techniques of all-night sleep recording--including measurements of eye motion and EEGs of brain activity--and used them to chart the sequence of sleep patterns, including dreaming, over the course of a night.

Later, Kleitman proposed the existence of a basic rest-activity cycle (BRAC), during both sleep and wakefulness.

Kleitman often used himself, friends, and family as research subjects for his many experiments. He kept precise records of his two daughters' sleep habits from infancy through college. He once kept himself awake for 180 consecutive hours to study the effects of sleep deprivation. He and an associate spent more than a month 150 feet underground in Mammoth Cave, Kentucky, to chart their daily fluctuations in wakefulness and body temperature free from the regulating influence of sunlight and daily schedules, and to determine how altering the normal 24-hour routine of sleep and wakefulness affected mental performance.

His discoveries about variations in mental alertness, made after two weeks in 1948 on the submarine known as Dogfish, demonstrated the difficulties of adjusting to shifting time schedules and emphasized the importance of the taking into consideration the body's regular rhythms in the scheduling of shift workers.

Kleitman was born in Kishinev, Russia in 1895, arrived in the United States in 1915, and became a naturalized citizen in 1918. He received his BS degree from the College of the City of New York in 1919; his AM from Columbia University in 1920); and his PhD, summa cum laude, from the University of Chicago in 1923). He was elected to Phi Beta Kappa and Sigma Xi. After a two-year research fellowship with the National Research Council, Kleitman became member of the University of Chicago faculty in 1925, where he remained until his retirement in 1960, when he and his wife, the former Paulena Schweizer, moved to California.

Kleitman and his wife celebrated 50 years of marriage shortly before her death in 1977. He is survived by two daughters and their husbands: Hortense Kleitman Snower (William Snower, Jr.) of Kansas City, Missouri; and Esther Kleitman (Steven A. Moszkowski) of Los Angeles.