French researcher unlocked secrets of REM sleep
Dr. Michel Jouvet, a neurophysiologist who discovered the region of the brain that controls rapid eye movement, and who helped define REM sleep as a unique state of consciousness common to humans and animals alike, was found dead on Oct. 3 in Villeurbanne, France. He was 91.
Pierre-Hervé Luppi, a fellow researcher who worked with Jouvet for many years, said he had died overnight at a hospital.
The curious physiological phenomenon known as REM sleep was first reported in the early 1950s by Eugene Aserinsky and Nathaniel Kleitman, researchers at the University of Chicago. They noticed that people who appeared to be sleeping soundly sometimes moved their fully lidded eyes, and that electroencephalogram recordings showed that brain activity during periods of eye movement was closer to that of someone awake than someone unconscious.
They and another colleague, William C. Dement, eventually determined that sleepers had intermittent periods of REM during which they often dreamed.
JOUVET WAS a researcher at the University of Lyon in France, studying how sleeping cats react to stimuli, before he turned his attention to REM in the late 1950s.
In deep, or slow-wave, sleep, both cats and humans show slight muscle tension and low brain activity. But Jouvet found that during periods of REM sleep the muscles of cats were completely slack, even though their brain waves suggested physical activity. He called the REM state “paradoxical sleep,” since the brain is active even though the body is virtually still.
“Dreaming became the third state of the brain, as different from sleep as sleep was from waking,” Jouvet wrote in “The Paradox of Sleep: The Story of Dreaming,” published in France in 1993 and in English six years later.
He determined that a structure within the brainstem called the pons governed cats’ REM sleep. The pons is responsible for basic biological functions, like breathing and sensory perception; by contrast, the cortex, a higher brain region, governs conscious thought and actions.
Many researchers at the time assumed that since dreaming seemed to be a complex intellectual process, it would be centralized in the part of the brain responsible for reasoning. Jouvet’s discovery suggested that REM sleep could continue without the involvement of higher brain structures and that it had an important biological function even for animals with little capacity for reasoning.
Research has since confirmed that human beings have brain structures that govern REM sleep similar to those found in cats. Most warm-blooded animals, like mammals and birds, have periods of REM sleep. (Many species of whales are notable exceptions.)
Jouvet also conducted early research on Modafinil, a stimulant used to successfully treat narcolepsy and other sleep disorders. Modafinil, intended to promote wakefulness with a lower risk of addiction than amphetamines, has become popular as a so-called smart drug.
Michel Jouvet ———