American Scientist

The Paradox of Sleep: The Story of Dreaming. Michel Jouvet. Laurence Garey, trans. 184 pp. The MIT Press, 1999. $25.

The student of brain function can consider the mechanism (the how) of sensation, movement initiation, learning, memory, language, basic drives or emotions with the comfort of knowing its purpose (the why). When investigating dreaming, however, this comfort is unavailable. Not knowing why we sleep and dream accounts in part for both the fascination and frustration of this area of neuroscience.

It is difficult to imagine a more desirable messenger of what is known about these two related topics than Michel Jouvet, the renowned French scientist who coined the term "paradoxical sleep." The Paradox of Sleep is both an academic treatment of the current knowledge about dreaming and a historical, somewhat autobiographical account of 40 years of sleep research. Although the book considers slow-wave sleep, dreaming and paradoxical sleep (also known as rapid eye movement, or REM, sleep), it is the second topic that is its major focus. Because most (although not all, as Jouvet fairly points out) sleep researchers believe that all or nearly all dreaming occurs during paradoxical sleep, the book is also very much about dreaming.

The book begins delightfully. In his first two sentences Jouvet informs us that he does not believe that one "needs coherent behavior in science," nor does he believe that one "can 'administer' research." Thus begins a colorful summary of four decades of sleep research amply laced with Jouvet's own philosophies, contributions and recollections. From here, he proceeds to a solid description of the neurobiology of dreaming. We learn about the ponto-geniculo-occipital "generator" of paradoxical sleep and about the physiological changes that accompany paradoxical sleep, including postural atonia, penile erection and REM. We also learn that although the functions of slow-wave, or nonparadoxical, sleep are still largely unknown, Jouvet believes that they have something to do with the deposition of energy reserves in the form of glycogen in the glial cells that "feed" neurons. Jouvet makes the intriguing suggestion, however, that this energy deposition may be to prepare the brain for the energy-draining process of dreaming rather than to prepare it for waking.

The remainder of the book is less analytical. Jouvet first considers studies on dream recall and dream "behavior," the latter giving us a glimpse of what actions an animal might perform if it were not paralyzed during its dreams. We next learn Jouvet's thoughts on the relationship between the "spirit," or mind, and dreaming. Along the way we are presented with a few of those delightful nuggets that make biology so interesting. For example, because the dolphin must voluntarily breathe air, it is faced with the choice of staying awake or drowning. Jouvet teaches us that the dolphin solves this problem by sleeping with one side of its brain at a time, while controlling respiration with the contralateral (awake) hemisphere!

Jouvet also considers hypotheses regarding the functions of dreaming. Although these are plentiful, none of them is supported by much evidence. Jouvet in fact shows us that paradoxical sleep can be suppressed in humans for very long periods—perhaps even indefinitely—with no discernible detrimental effects. Thus, whereas sleeping is clearly an essential body function, we must consider the possibility that dreaming is not. In his own hypotheses for the functions of dreaming, Jouvet postulates that during the dreams the brain is genetically "reprogrammed," an event that is necessary to preserve our individuality. Because this hypothesis is far-fetched and not well supported by hard data, I found this portion of the book to be the least enjoyable. Perhaps a scientist of Jouvet's accomplishments has, however, earned the right to ask us to listen to a personal idea about his specialty.

Jouvet ends with his reflections on where four decades of sleep research have taken us and on where we might expect to be taken in the future. This senior scientist nearing the end of his career clearly sees the next generation of researchers making obvious mistakes while showing exciting promise. These musings alone are reason enough to read The Paradox of Sleep. Although the book suffers from a lack of clarity in several brief passages, it can be recommended to neuroscientists, historians of science and informed laypersons alike.—Greg Fitch, Biology, Avila College, Kansas City, Missouri