A Treatise on the Incubus, or Night-Mare, Disturbed Sleep, Terrific Dreams and Nocturnal Visions

by John Augustine Waller

These are I believe the most common phenomena attending Night-Mare. I must beg leave, however, to remind the reader, that there are various degrees of this affection, as well as of the predisposition to it; all of which more or less disturb the rest, and derange the system. All unpleasant dreams may be considered as certain modifications of this peculiar affection; such as falling down precipices, or standing on their brink, or being in the midst of a torrent, or in imminent danger of our lives. If these ideas continue long, they generally produce a degree of consciousness that we are asleep, which is succeeded by an attempt to evade the danger by waking ourselves, which constitutes real Night-Mare.

There is, however, another kind, which differs a little from this I have been describing, but is nevertheless to be considered as a modification of Night-Mare, arising from the same cause, and requiring the same remedies; for which reason I shall include it in my History of that disease. I mean that undescribable terror which some persons feel in their sleep, and which frequently obliges them to vociferate loudly, and generally to start with violence, or sometimes even to jump out of bed. This terror is often, perhaps mostly, accompanied by some really terrific dream. This is not always the case, however, and when it does happen, the dream is rather to be considered as the effect of the terror, than the cause of it. I have frequently found this terror to be connected with some object, not at all in itself terrific; as for instance, a cat or a dog, or sometimes a little child which I had been contemplating in my dream for some time without any dread or terror, has all at once become an object of the utmost horror and alarm, and that without at all changing its appearance or attitude. A sudden panic has struck me with a degree of terror, which I am convinced nothing on earth could produce in me when awake; and which obliges me to vociferate with uncommon vehemence, and to start with so much violence as generally to wake myself immediately, and frequently great part of the family beside. It would be impossible by any words, to convey an adequate idea of the terror felt during this affection: the patient continues to feel it for several minutes after he is awake; at least it requires some little time for even a strong mind to recover its tranquillity. I have always observed in my own case, as well as in all those I have had the opportunity of investigating, that this kind of affection is universally accompanied with a sensation called shivering; not precisely of that kind which accompanies the paroxysm of ague, but that momentary sensation of shivering which people are apt to feel on hearing any tale of horror related, or frequently indeed, without any evident cause whatever. It is a vulgar opinion, that this shivering takes place whenever any one is walking over the future grave of the person who feels it. This kind of shivering is, at all times, accompanied with some degree of horror, and that has probably been the reason of the superstitious opinion above mentioned. Hence also the common expression, on hearing a tale of horror, that it makes the blood run cold; which is precisely the sensation of the person, both in the dreams themselves which we are speaking of, and for some little time after waking out of them. This sensation is always referred to the spine, and appears to descend from the neck to the loins. The cause of it is not very easy to explain; it evidently belongs to that class of sensations and affections which we call nervous, and appears in this case to be the immediate cause of that terror which invades us in sleep, by inducing some idea of great horror.

Amongst all the subjects of terror which infest the human mind, there is none so powerful as the idea, which is generally imbibed at a very early period of life, respecting ghosts and supernatural appearances; and there are comparatively few persons who, when alone and in the dark, are perfectly free from them. In sleep, however, we are all much more timid than when awake. I believe every person’s experience coincides in this opinion: hence it arises, that the idea of ghosts and spectres being the idea which inspires us with the greatest terror, is that which most readily and frequently presents itself to the mind, when the nervous system is suddenly agitated during sleep; a state when all objects of fear act with increased force. Whatever may be the cause which induces this kind of shivering during sleep, the shivering itself appears to me evidently to be the immediate cause of the terror, and the accompanying terrific dream; and this I conceive to happen from association; for as this shivering is the kind of involuntary sensation we feel when suddenly alarmed, or even when we hear or read a tale of terror, the feeling itself becomes so associated with terror, as always to recal to the mind, even in sleep, the idea of it; the sensation being the same as if the nerves had actually received some terrific impression; and as the imagination has full play when asleep, it is seldom long in furnishing the terrific object.

I have known these dreams to be succeeded by an hysterical affection, of involuntary laughing and crying; and they are, I believe, in all cases attended with a great degree of nervous irritability.

It will sometimes happen in this case, as in the preceding, that the patient does not awake from his dream, notwithstanding that his vociferations have been loud enough to wake all those who may sleep near him. When this happens he seldom or never has any recollection of his terror, and feels greatly surprised when told of the alarm he had given to others. The moment the shivering which produced the terror has ceased, this likewise ceases; and seldom leaves in the mind, any trace of its having existed: in this respect it differs greatly from the Night-Mare, in some others it appears to have some considerable affinity to that affection.

It is not uncommon for persons affected with these terrific dreams to leap out of bed, and attempt to escape from some imaginary danger by flight. Many instances have occurred of persons jumping immediately out of a high window under these circumstances: the same accident very lately occurred to a youth in this metropolis.

There are several other accidents to which our sleep is liable, but as they differ in their nature considerably from Night-Mare, we shall not here take any notice of them.

I shall now speak of the persons who are subject to Night-Mare, before entering into an investigation of its causes.

This affection may at some time or other occur to any person whatever, as it will for the most part be found to be the constant attendant upon indigestion: now the most healthy person in the world will sometimes meet with food which his stomach will not digest, and if he goes to sleep whilst such food is remaining in the stomach, or in the superior portion of the alimentary canal, he will certainly be affected with Night-Mare, to a greater or less degree. But a peculiar habit of body is necessary to render a person subject to it, so that it can become habitual. Many persons begin to feel its effects in very early youth; these are generally of a contemplative disposition, and of a peculiar temperament, which renders them liable to hypochondriasis and nervous diseases. To these persons the Night-Mare often becomes habitual. All who follow sedentary employments, or whose avocations keep them mostly in doors, more especially literary characters, and all studious persons, are the victims of these affections. Those likewise, who, although they do not want for air and exercise, yet are accustomed to a coarse and unwholesome diet; hence sailors are, of all classes of men, the most subject to Night-Mare and terrific dreams. All hypochondriacs, and frequently pregnant women, are amongst the subjects of these affections.

It occasionally accompanies fever and other acute diseases. I remember one patient to whom it became extremely troublesome in the last stage of consumption, who had never before in her life been affected by it. Sylvius Deleboe, who has recorded the history of an epidemic disease, which raged in the city of Leyden, in the year 1669, mentions the Incubus as a very common affection in it, with which he was himself afflicted to a great degree. He describes it as accompanied with an unusual degree of somnolency, and making its attack on the accession of the febrile paroxysm. Perhaps it was something of this kind, which Cœlius Aurelianus asserts to have been epidemic at Rome. Sylvius relates that the lethargy, or propensity to sleep, was so great during the febrile paroxysm, and accompanied with so unpleasant a sensation, even when Night-Mare did not come on, that he thought proper to order himself, as well as his patients, to be kept awake by the attendants. He describes it thus: “Non tantum cum Incubo, sed absque ipso gravis fuit ægris multis Somnus profundus, et insomniis multifariis molestus.” In another place, “Nec tantum sola difficili respiratione laborarunt multi, verum etiam Incubo nonnulli, et inter ipsos ego quoque; qui cum paroxysmis febrilibus repetens atque somnolentiam simul excitans, fuit mihi valdè molestus, donec ipsum agnoscens rogarem adstantes, ut tamdiu somnum in quem tam valde propendebam, interturbarent ac impedirent, donec paroxysmo declinante in somnum suavem ac commodum inciderem absque omni incubo.” Sylvii Praxeos. Med. Tract. x.