A text-book on physiology : for the use of schools and colleges : being an abridgment of the author's larger work on human physiology / by John William Draper ; illustrated with nearly 150 wood engravings.

  • Draper, John William, 1811-1882.
Date:
1866
Catalogue details

Licence: Public Domain Mark

Credit: A text-book on physiology : for the use of schools and colleges : being an abridgment of the author's larger work on human physiology / by John William Draper ; illustrated with nearly 150 wood engravings. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    physiologist, and the more so since it presents, in the various phenomena of dreams, significant illustrations of the manner of action of the nervous system. All animals sleep. Many, perhaps most, dream. The necessity for a season of repose arises from the prepon- derance of the waste of the system over its repair dur- ing our waking hours. By bringing the animal func- tions into a condition of rest, an opportunity is afforded for renovation, and the equilibrium can be maintained. In early infancy, when it is necessary for the nutritive operations to be carried forward with the utmost vigor, and attended with as little waste as possible, the whole time is spent in sleeping and eating. The waking peri- od is gradually increased as the child advances, but not so as to make it continuous, for the day is broken into intervals of sleep. Even at three or four years of age we sleep more than once a day. In mature life eight hours are on an average required, but the precise time varies with different individuals, and even with the same individual in different constitutional states. The time is not, however, always a true measure of the amount of rest, for sleep varies very much in the degree of its com- pleteness or intensity; there is a slumber so disturbed that we are unrefreshed by it, and a sleep so profound that we awake weary. Old age, as it advances, admon- ishes us to spare the system as much as we may, for re- pair is conducted with difficulty; and this period, char- acterized by its resemblance in so many respects to child- hood, like it, is often marked by frequently-recurring and prolonged slumber. Moreover, various accidental and other circumstances are liable at all times to disturb its proper periodicity—a warm afternoon, a hearty dinner, an ill-ventilated apartment, monotonous sounds, the at- tention devoted to one object, bodily quiescence, ceas- ing to think, the use of narcotics, extreme cold, a hori- zontal position, etc. Sleep is commonly preceded by a sense of drowsiness of more or less intensity, gradually followed by a loss of sensibility. Objects cease to make an impression on the eyes, the lids become heavy and close. If we are What are the causes for the necessity of sleep ? Is there any fixed period for the duration of sleep ? What is the order in which the senses are affected?