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In its multiplicity of anecdotes this study of sleep[1] resembles the early works of Ribot, and the author chats about each in an equally charming and irresponsible fashion. She is not chary, however, of generalizations, and a very limited number of examples suffices for wide inductions. In the regions of physiology and hygiene she gives a careful account of the phenomena of sleep, supple meriting these with valuable suggestions of her own. It is only when she enters upon the pathology and psychology of her subject that she betrays herself as one of that school, mostly French and Italian, which may be called the romancers of science.
She laments that we understand so little about sleep, which absorbs one third of our lives. The extensive bibliography added to each chapter would seem to disprove a want of scientific attention. The circulation in the brain during sleep has been observed in animals by substituting a watch glass for a portion of the bone of the skull. Experiments have shown also that a withdrawal of blood from the brain precedes sleep, and all conditions tending to this result produce sleep. Heat or excessive cold, which draws the blood to the skin, is followed by drowsiness, and this is likewise the consequence of digestion which summons the blood to the large abdominal vessels. Debility and great loss of blood also cause cerebral anasinia and somnolence.
If it be inquired what is asleep within us, we find that it is only a part of the brain. It is possible for all the organs of the body to be active during sleep excepting partially the nervous system. The voluntary muscles are awake, also the sensory nerves and the cerebral centers controlling each. Only because the different nervous channels are sensitive is it possible to arouse a sleeping person. The author considers that the fact of being able to awake at a given time proves that the attention and will preserve their activity. After investigating the many hypotheses in regard to the causation of sleep, the conclusion is reached that sleep is the resting time of consciousness.
The pathological modifications of sleep embrace weakened and excessive activity. Complete insomnia is found only among the insane or extremely anæmic. Intermittent sleep is injurious, since there is not time in the fugitive rest obtained for adequate nutrition of the tissues, Partial insomnia is met with in persons who are liable to a flow of blood to the brain and those with unbalanced and irritable nervous systems. It is also the result of mental overstrain or extreme physical fatigue. On the other hand, excessive sleep has its attendant evils—the gradual weakening of consciousness and the mental faculties, and the production of serious physical disorders. Among rarer forms of pathological sleep the author discusses narcolepsy, latah, hypnosis, and somnambulism.
The hygiene of the subject brings up interesting questions. How much time should be given to sleep? What should be the light, temperature, and ventilation of the bedroom? Should habit control us? It is contended
- ↑ Sleep: Its Physiology, Pathology, Hygiene, and Psychology. By Marie de Manacéine. New York: Imported by Charles Scribner's Sons. Pp. 341. Price, $1.25.
