The Night-mare or Ephialtes, incubus, from efa???a?, “to leap upon,” and incubo, “to lie upon,” may be considered a sympathetic affection of the brain during our sleep, generally arising from a derangement in the digestive functions. We therefore observe it after a heavy supper, or the use of any article of food of difficult digestion. It is to these circumstances more than to the “unusual loss of volition,” which some physiologists consider as its cause, that we are to attribute this unpleasant perturbation of our repose, which impresses the sleeper with the idea of some living being pressing upon the chest, inspiring terror, impeding respiration, and subduing all voluntary action that might endeavour to remove the unwelcome visiter. It has been observed that persons of a melancholy and contemplative disposition are more subject to it than the gay and the vivacious. Sedentary employment and anxiety of mind often bring it on; and it has been noticed in nostalgia, or regret of home, in soldiers and sailors. The sense of apprehension remains after the sufferer is awakened, and the fluttering of the heart and quick pulse are observed for some time after, while drops of cold perspiration frequently trickle down his brow. When the night-mare is the result of too much repletion, it is possible that its symptoms denote a pressure of the loaded stomach on the solar plexus.

It is said that the night-mare derives its name from Mara, an evil spirit of the Scandinavians, which, according to the Runic theology, seized men in their sleep, and deprived them of the powers of volition. Our old Anglo-Saxon name for the disease was Elf-Sidenne, or elf-squatting; hence the popular term “hag-ridden.”

There is a variety of the malady which makes its attack by day, and when waking: it has been called the day-mare, or ephialtes vigilantium. This affection, although uncommon, has been noticed by Forestus, Rhodius, Sauvages, and Good. Forestus has known it to return periodically like an intermittent fever.

It is not always that the patient experiences unpleasant sensations in these nocturnal attacks, which were not unfrequently of a curious nature. The ancients thought that these intruders were sometimes sportive Fauns; hence Pliny calls the affection ludibria Fauni. At a subsequent period, superstition replaced the Fauns by Incubi, or evil spirits, who visited the earth to destroy virtuous women; and it was once gravely discussed by the Sorbonne, whether the offspring of such an union should be considered human, or the fair lady’s reputation injured by the involuntary act of giving a young incubus to the world. The absurd stories of the pranks of the Succubi and Incubi are well known.

Ephialtes has been known to be epidemic, and has attacked numbers at a time. CÆlius Aurelianus informs us that Silimachus, a disciple of Hippocrates, observed the phenomenon in Rome, when the disease generally proved fatal. It is more than probable that in these cases the night-mare was merely symptomatic of other complaints. A French physician, Dr. Laurent, however, has related a very curious instance of a species of night-mare attacking an entire regiment; he thus relates the singular occurrence:

“The first battalion of the regiment Latour d’Auvergne, of which I was the surgeon, was garrisoned at Palmi, in Calabria, when we received a sudden order at midnight to march with all possible speed to Tropea; a flotilla of the enemy having appeared off the coast. It was in the month of June; we had a march of forty miles of the country, and only arrived at our destination at seven o’clock the following evening, having scarcely halted during those thirty-one hours, and suffered considerably from the heat of the sun. On our arrival the men found their rations cooked and their quarters prepared; but, having arrived the last, our regiment had the worst accommodation, and eight hundred men were pent up in a building scarcely capacious enough for half the number. The soldiers were in consequence much crowded, and slept upon the straw without any bedding, and most uncomfortably. The building was an abandoned monastery; and the inhabitants warned us that we should not be able to occupy it quietly, as it was haunted every night. We laughed at their superstitious fears, but were much amazed when, towards midnight, we heard loud cries, and the soldiers rushed tumultuously, and in evident terror, out of their rooms. Being interrogated as to the causes of this alarm, they all affirmed that the devil was in the abbey; that they had seen him enter in the shape of a large black dog, that had jumped upon their breasts and disappeared. To convince them of the absurdity of their fears was of no avail; not a single man could be persuaded to return to his quarters, and they wandered about the town until daybreak. On the following morning I questioned the most steady non-commissioned officers and the oldest soldiers; and though under ordinary circumstances they were strangers to fear, and never gave credit to any tales of supernatural agency, they assured me that the dog had weighed them down and nearly suffocated them. We remained that day in Tropea, and had no other quarters to occupy but the same monastery, and the soldiers would only take up their residence on the condition that we should remain with them: the men retired to sleep—we watched; all was quiet until about one in the morning; when they awoke in the same terror, and fled from the building in dismay. We had looked out most attentively, but could not perceive the cause of this commotion. The following day we returned to Palmi; and, although we marched over a great part of Italy, and were frequently equally crowded and uncomfortable, a similar scene never recurred.”

Dr. Laurent very judiciously attributes this singular attack to the pernicious local influence of some deleterious gas, and the very crowded state the men slept in. It is also probable that they did not take off their accoutrements, and lay down with their belts on: might they not also have eaten some unwholesome fruit upon the line of march, for it was in the month of June, when various berries grow in abundance along the road-side?

Hippocrates’s theory of the night-mare was, that, during our sleep, our volition being suspended, the soul, still awake, watches over all the functions of the body. It is rather odd that the animal that most persons pretend to have thus annoyed them, is a long-haired black dog. Forestus assures us that it was a similar visiter that tormented him in his youth. This circumstance can only be attributed to vulgar superstition and tradition. Dubosquet has preceded his Treatise on Ephialtes with the engraving of a large monkey who had perplexed a young lady whom he attended; the monkey most probably came on horseback, as his steed is also delineated looking over the sleeping victim.

Various medicines have been recommended to prevent these attacks; amongst others, saffron and peony: and several learned commentators have endeavoured to prove and disprove that they were only specific in the form of an amulet. Zacutus Lusitanus recommends aloes, and his advice is perhaps as good a one as could be given. The ancients attributed many powerful effects to saffron, and, amongst other properties, it was considered as an effective narcotic, and was said to occasion violent headaches. Curious anecdotes are related of its effects. Amatus Lusitanus having exhibited this medicine to accelerate a tardy accouchement, the woman was delivered of two yellow daughters; and Hertodt, in his work called Crocology, relates that, having tried it on a bitch, all her pups were of a similar colour. The ancients called saffron the king of plants, the vegetable panacea, and the soul of the lungs. In modern times we do not recognise any peculiar property in this production; and in Spain and Italy it is used as a condiment with perfect impunity. Peony was also deemed a valuable remedy, when gathered as the decreasing moon was passing under Aries: the slit root being then tied round the neck of an epileptic person, he was forthwith cured. “Unlimited scepticism,” Dugald Stewart observes, “is as much the child of imbecility as implicit credulity.” How difficult it is to steer the vessel of our understanding between those shoals!

Medical writers have divided the night-mare, according to its phenomena, into complete, incomplete, mental, and bodily. The complete night-mare, in which the suspension of the functions had been so powerful, has been known to prove fatal. In the incomplete, we fancy ourselves placed in a peculiar situation, opposed by some unexpected obstacle, and all our efforts seem of no avail to extricate ourselves from our difficulties. There is an incubus, called indirect, in which the dreamer is not the individual arrested in his movements; but he is impeded in his progress by the stoppage of his horse, his carriage, his ship, which no power can propel. In the mental or intellectual night-mare, the flow of our ideas is embarrassed, all the associations of our very thoughts appear to be singularly unconnected; we think in an unintelligible language; we write, and cannot decipher our manuscript: all is a mental chaos, and no thread can lead us out of the perplexing labyrinth. In the corporeal ephialtes, we imagine that some of our organs are displaced, or deranged in their functions. One man fancies that a malevolent spectre is drawing out his intestines or his teeth: a patient of Galen felt the cold sensation of a marble statue having been put into bed with him. These, however, are nothing else than the actual sensations we experience at the time. Thus Conrad Gesner fancied that a serpent had stung him in the left side of the breast; an anthrax soon appeared upon the very spot, and terminated his existence. Arnauld de Villeneuve imagined that his foot had been bitten, and a pimple which broke out on the spot soon degenerated into a fatal cancerous affection. Corporeal night-mare may therefore be simply considered as a symptom of disease, and not as a mysterious forewarning.

The cold stage of fever that often invades us in our sleep is the natural forerunner of the malady. This was the case with Dr. Corona, the physician of Pius VI. who upon two occasions was attacked with typhus fever, ushered in by a distressing dream or incubus. These physical phenomena only strengthen the opinion, that in our sleep we are equally alive to mental impressions and bodily sufferings; and that, correctly speaking, there is no suspension of our intellectual faculties of perception, nor is there any interruption in the susceptibilities of our relative existence. The various doctrines regarding dreams illustrate this position.