CHAPTER II. INSOMNIA, OR WAKEFULNESS.

Causes of insomnia--Affections of the organs of special sense--Effects of light--Effect of sound--Impressions upon the organs of smell and taste--Disturbances caused by a high temperature--Atmospheric and electrical disturbances-- Effects produced by cold--Hibernation of animals-- Disturbances of sleep occasioned by painful sensations-- Disorders of the sympathetic nerves--Morbid states of the central nervous organs--Disorders of circulation and nutrition--Hyperæmia of the brain--Anæmia and starvation of the brain--Effects of tea and coffee--Effect of alcohol-- Inflammations, degenerations, and tumors affecting the brain--Excitement of the brain by diseased conditions of the blood. 38