Finally, it must be observed that wakefulness may result from excitement of the brain by irritating substances transported through the blood from distant centers of disease in remote organs of the body, or derived from articles that have been absorbed with the food and drink, or with the air that enters the lungs. Thus wakefulness may accompany cutaneous disorders that interfere with perspiration. Imperfect elimination through the liver, kidneys and intestines, leaves the blood charged with excrementitious substances which arouse the brain to wakefulness. In like manner, various poisons, like lead, arsenic, etc., different miasms of telluric origin, the products of putrefaction, and the various animal contagia, may produce insomnia by their prejudicial effect upon the nutrition of the nervous structures throughout the body.
O, true apothecary! Thy drugs are quick. --ROMEO AND JULIET.
An occasional attack of wakefulness may fall to the lot of any one as a consequence of the various disturbances of health or equanimity of mind to which all are liable. Occurring as an accident in a state of health, it produces merely a feeling of lassitude and weariness during the subsequent day. This soon disappears, after a night of refreshing sleep, and the subject is nothing worse for the incident. But the recurrence of the disorder is a thing to be deprecated, not only for the reason that it denotes a departure from the physiological order of life, but because its frequent repetition prevents the adequate repair of the tissues of the body. The great function of nutrition suffers as a consequence, and the patient rapidly falls into a condition of premature old age. When this takes place as a result of some temporary error of hygiene, or as a consequence of diseases which admit of successful treatment, the patient may be restored to health by judicious management, but lost youth and elasticity of the tissues can never be fully regained. The most formidable cases of insomnia are those for which no adequate cause can be recognized in the habits, mode of life, and state of health of the patient. Grave and permanent disorder of the brain is then to be feared. Such wakefulness is a frequent precursor of acute meningitis in children and adults. It frequently ushers in the early, insidious, formative stage of tubercular meningitis, and of the infective fevers--notably typhoid fever. It forms one of the most suspicious symptoms among the introductory phenomena of insanity; and during the course of protracted diseases, its intrusion is an omen of most unfavorable augury. It will, therefore, be found useful to consider with some degree of detail the circumstances under which insomnia may occur, and the best means of averting its onset.