affects all the bodily functions, exercises a great influence upon the duration of sleep. Those who, from necessity or from choice, remain awake through the night, learn to feel, it is true, as soon as the habit is well established, no necessity for nocturnal sleep, yet the enfeebling of their forces and impoverishment of their blood are the usual consequences.
In regard to the influence of temperament, it may be observed that a plethoric habit of body, kept up by a full diet, especially of animal food, predisposes to sleep, provided the digestive powers are in vigorous condition. Persons of lymphatic temperament are usually great sleepers. Thin, wiry people, on the other hand, in whom the nervous temperament predominates, usually require comparatively little sleep; but their slumber, while it lasts, is very deep.
The amount of sleep is greatly influenced by habit, and, contrary to what might have been anticipated, we find that exceptionally brief sleepers have generally been men of the greatest mental calibre. Thus, Frederick the Great, John Hunter (the often-quoted surgeon), and the first Napoleon, are said to have required only 5 hours' sleep out of the 24. As a general rule, from 6 to 8 hours of repose are required in the 24 to keep the system in a state of healthful activity.
Usually, when people are abruptly aroused from profound slumber, the action of the heart becomes quickened or otherwise disturbed. The effects of a habitual deficiency of sleep are a sense of wretchedness and prostration, frequently accompanied by great restlessness.
Headache, fulness, heat, throbbing and various other unpleasant sensations about the head, give warning that the brain is being over-tasked, and, should this warning pass unheeded, sleep, which at first it was difficult to resist, becomes even more difficult to obtain; a state of general restlessness and feverish excitement is induced; and if, in spite of this, the mental task be continued, serious consequences are almost sure to be induced.
In average health, the best cure for sleeplessness is duly regulated exercise of body and mind. Among the simpler and hygienic means of promoting sleep is cold water, or cold water and vinegar, sponged over the forehead and temples when the restlessness appears to be due to congestion and heat about the head.
Mental activity and consequently sleeplessness, mean an excess of blood in the brain. A very efficacious method of procuring sleep after lying awake for some time is to take a small quantity of food, e.g., a glass of milk and a biscuit. This stimulates the digestive organs, draws the excess of blood from the brain into the abdomen, and speedy sleep is the result.
The bed-chamber should be well-ventilated. It is best to lie upon an inclined plane, or with the head moderately raised, but not so high as to produce any strain upon the muscles of the neck. Complete darkness should be secured as far as possible. Anxiety and excessive
