If such phenomena take place in persons of healthy brains, the greater liability of the insane to experience them will readily be admitted.
The character of dreams, as Macario[102] remarks, varies according to the type of insanity to which the patient is subject. In melancholia they are ordinarily sad and depressing, and leave a deep and lasting impression; in expansive monomania they are gay and exciting; in mania they give evidence of the extraordinary mental excitement and activity of the subject, and in duration they are vague, fleeting, and occur but seldom.
Essential Morbid Dreams.—Under this head are comprehended the various forms of frightful dreams which are ordinarily designated under the name of nightmare. It has been my good fortune to have had the opportunity of carefully studying the phenomena of this singular affection in several persons of intelligence, and I propose, therefore, detailing the results of my own experience, after a short historical retrospect, which I hope will not prove uninteresting.
Nightmare is characterized by the existence during sleep of a condition of great uneasiness, the principal features of which are a sense of suffocation, a feeling of pain or of constriction in some part of the body, and a dream of a painful character. There are thus two essential elements of the affection—the bodily and the mental.
At a very early period the phenomena of nightmare attracted the attention of physicians. Hippocrates[103] describes it in the following words: “I have often seen persons in their sleep utter groans and cries, appear as if suffocated, and throw themselves wildly about until they finally waked. Then they were in their right minds, but were, nevertheless, pale and weak.”
The general opinion held at that time was that the phenomena of nightmare were due to excess of bile and dryness of the blood. This view originated with Hippocrates, but was more or less modified by subsequent writers.
After the establishment of Christianity, the conviction began to prevail that during an attack of nightmare the subject was visited by a demon, who, for the time being, took possession of his body. Oribasius, in the fourth century, combated this idea, and endeavored to show that it was a severe disease, which, if not cured, might lead to apoplexy, mania, or epilepsy. He located it in the head.
Aetius also denied the existence of demoniacal agency in nightmare. He considered it as a prelude to epilepsy, mania, or paralysis.
During the middle ages nightmare was attributed to the power of the devil. Imps, male and female, called incubi and succubi respectively, were supposed to be the active agents in producing the affection. The treatment was in accordance with the theory, and consisted of prayers and exorcisms. Not unfrequently the subject of the disease perished at the stake for the alleged crime of having sexual intercourse with incubi or succubi, according to sex.
Even in later times many persons have been found who believed implicitly in the reality of the visions which they experienced during an attack of nightmare. Thus Jansen[104] relates that a clergyman came to consult him. “Monsieur,” said he, “if you do not help me I shall certainly go into a decline, as you see I am thin and pale,—in fact, I am only skin and bone; naturally I am robust, and of good appearance; now I am scarcely more than the shadow of a man.”