Part 3

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.

It sometimes appears in very early life, in which case it generally sticks close to the patient, almost all his days. In some, however, such a change in the constitution takes place at puberty as destroys altogether that predisposition to this affection, which existed in early life.

Females appear much less subject to it, than males, though by no means exempt. Of these, virgins and pregnant women are more particularly liable to its attacks, as well as all those who are much visited by hysterical affections, constipation, and flatulency. It is sometimes also found to accompany the chlorosis or green sickness. On the whole, however, it is of comparatively rare occurrence amongst females.

Neither is this disease very common in advanced life, unless where corpulency, or a tendency to lethargy exists. In those cases however where it does occur, it is more to be dreaded than in youth or middle age. It is no unfrequent attendant on asthmatic persons.

The opinions of medical men with respect to the immediate cause of this disease, or what by them is termed its proximate cause, have been various and discordant, as generally happens in all obscure investigations. In all probability every one of them are wrong, so that it can be of little utility to inquire into them. There is however one idea, which seems to be more universally adopted than any other, and which deserves notice; it is, that this affection is produced by a cause purely mechanical, and depending on the position of the body. Some plausible theories have been formed on this supposition, by assigning to the different thoracic and abdominal viscera, certain relative positions which would occasion a temporary pressure upon the organs of respiration, or upon some branch of the intercostal nerves. With respect to this mechanical pressure, arising from any imagined position of the patient, what I have already said on that score, renders this hypothesis vain, for there is no position in which it is possible for a person to fall asleep, in which I have not been attacked by Night-Mare. Neither is there any more dependence to be placed on the generally received opinion, of the disease being induced by a full stomach. It may naturally be supposed, that any person labouring under this affection to the degree which I have stated, although I have as yet given a very feeble idea of its extent, would take every possible precaution to keep clear of the causes, which were so generally believed to have produced it. I religiously abstained, for many years from eating any thing after dinner, and took dinner also at as early an hour as two o’clock. It was during this period that I suffered most from the disease. I think I may safely assert, that for more than twenty years, I have never once, to the best of my recollection, fallen asleep on my back, or ever found myself in that position on waking. When night after night has been rendered miserable by this enemy of repose, I have had recourse to every expedient which deep reflection could suggest. The perpendicular position of the body, I have found by experience to be the worst in which a paroxysm of Night-Mare can be borne. The difficulty of respiration, and all the other symptoms are greatly aggravated, and an additional one is felt, which greatly increases the sufferings of the patient; it is a perpetual dread of falling, which appears inevitable, and which prevents the patient from struggling so much as he would do if in a horizontal position. Next to this is the position of sleeping with the body bent forwards, and the head reclining with the face downwards on a table: in this last position, the difficulty of inflating the lungs is extreme. I have never been able to discover that any great difference arose between sleeping on the right or left side. I have always considered it as a matter of indifference. Although it is possible to render the paroxysm of Night-Mare more tolerable by any particular position of the body, yet I am well assured that no position will secure a person from its attacks, to whom it has once become habitual. I slept for some time in an easy chair, and found the disease greatly aggravated by it.

There must however be some reason for the universal opinion that it always attacks persons lying on the back. I was for a long time of opinion myself, that I was always lying in that position when the paroxysm came on, but as the disease gained strength, and the paroxysms hung more pertinaciously upon me, I became more perfectly awake, so as to be able to discover more accurately the position in which I was lying, and I found that little faith was to be given to the sensations that may occur during Night-Mare, as they are the most deceitful of all evidences. It appears to be one of the symptoms almost inseparable from the disease, that the patient should appear to himself to be kept down upon the back by some external force. This sensation I have almost always felt, even when I have had the evidence of other people, as well as my own conviction when awake, that I was in reality lying on the side. I cannot help suspecting that many others have been deceived in a similar manner, and thus made to believe, that they never had the Night-Mare except when sleeping on their backs. There is also another sensation which is very apt to deceive the patient, that is, on the paroxysm going off, and the moment of his recovering the power of volition, a great confusion of ideas always takes place, and a person to whom the Night-Mare is not very familiar, generally imagines that he has recovered himself by some effort of his own, frequently by turning from his back to his side, sometimes by sitting upright in bed. These things are all extremely fallacious; there is no trusting to the senses during a paroxysm of Incubus; nothing short of the evidence of another person ought to satisfy the patient. I have often been thoroughly convinced in my own mind that I had succeeded in throwing the bed-clothes off my breast, and by that means gained relief, and not unfrequently, that I had risen from bed, and opened the window to admit air; yet both these ideas have been proved to be incorrect. I have often felt very certain that my right arm was out of bed, and that I had moved it about; but on waking thoroughly, I have found it under the bed-clothes, and in a situation in which it could not have been moved. I cannot help thinking then, that the universal idea of its attacking persons exclusively lying on the back, is founded on an error, arising out of the ordinary sensations of the patients themselves, who have always that idea, let them be in what position they will. Several persons, subject to habitual Night-Mare, have become convinced of the truth of this observation, which I had made to them, after attending more closely to their real situation during the continuance of, and immediately after the paroxysm. I have also convinced one or two medical friends, who were extremely sceptical on that point, that it would attack me in any position, by going to sleep before them, on a chair, or sofa, when my own feelings have indicated the certainty of attack, if I should indulge for a few moments the propensity I felt to sleep.

Neither is it necessary for the stomach to be filled with food, in order to produce Night-Mare, as is evident from what I have stated above with respect to the abstinence I observed during the period in which I suffered most from this affection. Experience has taught me that I may eat heartily of some kinds of food, just before going to bed, with impunity; whilst the smallest quantity of some other will inevitably bring on the disease, in spite of all the precautions that can be taken.

Thus then we must give up every explanation of the phenomena which occur in this disease, founded upon principles purely mechanical, however plausible they may appear. Neither is the opinion of Darwin more correct, that the Night-Mare is nothing more than a consciousness of the suspension of the power of volition, and a desire to recover that power. If so, it would differ little from sleep itself; or, however fatiguing it might be to the mind, it could not occasion any derangement in the functions. The breathing and the circulation would go on without any interruption, as in sleep; nor would there be any thing that could produce the sense of oppression on the breast. Darwin was well aware of this difficulty, and therefore chose rather to contradict the generally received opinion of oppression and difficulty of respiration. There is no doubt whatever of the difficulty of breathing, which any one may assure himself of, if he could have the opportunity of seeing a patient during the paroxysm of Night-Mare. I have taken considerable pains to assure myself of this circumstance from the evidence of other persons.

I must confess I have not hitherto been able to find any satisfactory explanation of the phenomena which take place during Night-Mare. The following observations which I have been able to make on the paroxysm itself, and on the more immediate causes which give rise to it, may possibly direct some happier genius to a more correct idea of its nature.

1st. I have frequently experienced that this affection may occur in very profound sleep, without breaking or disturbing that sleep, any farther than to produce a dream, the memory of which will remain after waking, in the same manner as that of any other impressive dream. Thus I have frequently dreamed that I had Night-Mare; supposing myself to be in a place, and under circumstances very different to those in which I really was. Under these circumstances I have never become conscious of the real situation in which I was, but on waking, remembered very well that I had been dreaming of labouring under Night-Mare. From this circumstance I conclude, that the Night-Mare is not, as Dr. Darwin insinuates, a state of imperfect sleep, but an absolute disease, which may occur, and go through its regular stages, whilst the patient continues to be, to all intents and purposes, in a natural sleep. There is no doubt but the disease, in this case, is much slighter than ordinary, although the impression made upon the mind may be very strong.

2nd. It happens still more frequently, that the patient is in a state apparently between sleeping and waking, when the paroxysm takes place; which has given rise to the belief, in many persons, that it came on while awake. I have often heard it described by others, (and have felt it myself) as a sense of weight, first upon the feet, and progressively advancing towards the breast, until the paroxysm becomes complete. In the beginning of this state of things, it appears to the patient that he might easily, if he would, move himself, and shake off the incumbent weight. He does not feel at all aware at that moment, of the suspension of the power of volition; nor does he feel any inconvenience from that circumstance until he begins to experience a necessity of exerting that power, in order to carry on the function of respiration. It is not until the involuntary action of the muscles concerned in respiration, in some measure ceases, that the patient perceives that he is absolutely labouring under Night-Mare.

I have paid very close attention to this circumstance, and have been repeatedly convinced, that whenever the disease attacked in this manner, I was always asleep at the commencement of the paroxysm, and that as soon as I became conscious of my situation, or in other words, awake, the power of volition was completely suspended, although very little inconvenience arose from it; for, on making the attempt to move, which appears very easy to do, I have always felt the paroxysm of Night-Mare to be completely formed, and the difficulty of respiration, which before did not exist, immediately to come on, and with it all the anxiety and distress which characterize this disease.

From this I infer, that a suspension of volition always exists during a paroxysm of Incubus, but that this is not alone sufficient to constitute a complete Night-Mare, even when attended with a consciousness of our situation. It is likewise necessary that the involuntary action of the respiratory organs should experience some interruption, and I am disposed to think that the circulation through the lungs, and the action of the heart itself, partakes of this interruption. I conceive also, that the difficulty of inflating the lungs is always increased in proportion as the patient becomes more awake.

3d. It has almost constantly occurred to me, especially since the disease had gained such considerable strength, that the power of volition has been partially recovered for some time before the paroxysm ceases. I have always recovered this power, first in the lower extremities, and last of all in the head. It begins first to return in one or both feet, and by moving them about as well as circumstances will allow, I recover by degrees the command over the muscles of the legs and thighs, and afterwards of the arms, but partially, and not without great exertion, which exhausts me much, and does little good towards shaking off the paroxysm. I have however at sea frequently profited by this power, for I have been able to communicate a considerable motion to the cot in which I slept, by pushing against the foot of it with one of my feet, until it swung so much as to touch against something, and by that means produce a shock, which being external, has frequently dispelled the fit. It is really surprizing how slight an impression from without is sufficient sometimes to recover the patient. Although I have frequently rolled about the bed, and kicked all the bed-clothes off from me, I have not been able to succeed for a long time in recovering myself from the paroxysm, when it has instantly disappeared on receiving a moderate shock from another person, or even by any one taking hold of my hand.

It is only however in the advanced stage of the disease, that this severe struggle takes place. In the general way the patient is instantly liberated from the paroxysm, as soon as he can succeed in moving any of his limbs. I have seldom met with any one who was able to articulate during the paroxysm, though I have generally been able myself to call any person by name, who might be near me, and to beg of them to wake me, but this is always effected with difficulty, and only after the paroxysm has already continued some time.

4th. It frequently happens, especially when a person is anxious about rising at a particular hour, and afraid of over-sleeping it, that he becomes conscious of that circumstance in his sleep, and feels an ardent desire to wake himself; to many persons this is by no means a difficult task, and is soon accomplished; but to those who are subject to Night-Mare, the reverse of this takes place. They strive with all their might to awake, and soon become conscious of their precise circumstances, but cannot recover the power of volition; after contending for this a short time, the breathing at length becomes laborious, and a complete paroxysm of Night-Mare succeeds, which always is severe in proportion as the patient happens to be more perfectly awake.

From these observations it results, that the nature of Incubus is essentially different to that of either sleeping or waking, and is an absolute state of disease which may occur during sleep in a slight degree, without breaking that sleep; that it consists in a suspension of the power of volition very different to what takes place in natural sleep, because it is accompanied with a consciousness of that suspension, and a strong desire of recovering this power. But neither is this sufficient to constitute Night-Mare, although this disease will, I believe always, result from such a state of things, yet the paroxysm is by no means complete, until, in addition to the general paralysis of all the muscles of voluntary motion, there shall occur likewise a partial paralysis of some of those concerned in the functions, which are performed independently of the will, especially of respiration and the circulation of the blood, the consequence of which will be a difficulty of breathing, with a sense of oppression about the præcordia, and fluttering of the heart. I conceive these symptoms to arise principally from a temporary paralysis of the nerves of the diaphragm; or rather an inaptitude in those nerves, together with some others of the principal branches of the intercostals, to perform their functions. Thus then, from this partial paralysis of the diaphragm and thoracic muscles, the patient is rendered incapable of dilating the chest so as to allow of the expansion and consequent inflation of the lungs; the blood consequently meets with some interruption in its passage through that organ, and this interruption is speedily communicated to the heart; the re-action which takes place here is quickly communicated to the whole system, and probably is the principal cause of the final solution of the paroxysm. How this solution is at length effected is, I confess, a difficult and obscure question. There are two ways in which it takes place; the first and most frequent is by the patient becoming perfectly awake, by which means he recovers at once the power of volition, and the partial paralysis of the diaphragm and thoracic muscles at the same moment ceases, these muscles being then moved by the power of the will. The other mode by which a solution of the paroxysm is effected, is by the patient falling into a more perfect sleep, and losing that consciousness which accompanies Night-Mare. The involuntary actions then go on as before without interruption, and if the dreams continue, they are no longer of that harassing and distressing kind, but are now natural and easy. It is not only in slight cases of Incubus that the patient recovers from the disease without waking, but sometimes I have known it to happen even in very severe paroxysms, where I have become conscious of the place and situation in which I was, and yet have instantly been asleep on the cessation of the paroxysm. There appears to me a greater difficulty in explaining this mode of the solution of the paroxysm than the other, as there seems no evident cause for the cessation of the paralysis of the Diaphragm, &c. Every thing connected with the phenomena of sleep, is extremely obscure; and nothing on this subject appears to me more extraordinary, than the sudden transition from the sleeping to the waking state. Whatever it is which takes place at that moment in the brain, and in the whole system, takes place only partially during Night-Mare. Is it very absurd to suppose that a part of the system may recover the waking state, while the brain, or some other part, remains asleep, for want of a sufficient stimulus to rouse them? I cannot help thinking but something very similar to this takes place in Night-Mare: hence the power of moving the lower extremities, whilst the superior ones remain paralyzed: hence the little good resulting to the patient from his own struggling, whilst a comparatively slight touch from another person is sufficient to dispel the charm. Hence the appearance of visions, whilst in every respect the patient appears to himself to be perfectly awake. It seems that the brain continues to present a succession of images to the mind as in sleep, whilst at the same time, the body is become susceptible of external impressions, and conscious of internal ones, such as those arising from the derangement which has taken place in the functions of the heart and lungs.

I am aware however of the obscurity and difficulty of this subject itself, as well as the difficulty of expressing in accurate language, the ideas which arise in my own mind concerning it. I have used the term paralysis in speaking of the state of the diaphragm and other muscles during the paroxysm of Night-Mare; this expression however, must be understood in a different manner from that in which it is usually applied in medicine; for in Night-Mare there remains always a consciousness of the inability to move the muscles, and constant attempt at the same time to move them; this appears to be as constantly impeded by some external force acting against the efforts of the will: thus, when my hand and arm are lying uncovered, and in a position which easily admits of moving it, I am able, by repeated exertions, at length to raise it and bring it to my head, but the effort which it requires is equal to what in the waking state, would raise a covering, which might be laid over it, of twenty pounds weight: should a part of the sheet, or even a handkerchief be lying over the arm thus situated, the difficulty would be greatly increased; and the operation, if effected, would so much exhaust me, that I should be obliged to desist for some time from any further struggling, and the respiration at the same time would be greatly accelerated. Nothing of this kind occurs in paralysis, properly so called; for the patient is not even able to direct any effort of the will to the paralyzed muscles, and frequently is scarcely conscious of their existence. These two kinds of paralysis evidently differ considerably from one another, and ought not to be expressed by the same term.

In giving my opinion of the causes of Night-Mare, I feel still more embarrassed for proper terms to express my ideas, than in explaining its nature. I have already said, that I conceived the ancient physicians to be well acquainted both with its nature, cause, and mode of cure; it might be well to take some notice here of their opinions, especially as to the causes which produce the disease, and the means by which it may be removed, as these two things depend in a great measure on one another. In order to render these opinions understood by those who have never read any of the ancient writers of medicine, from a mistaken idea of their not being worth the reading, I must premise, that they considered the nerves to be the conductors of a certain subtile fluid, by means of which the muscles are made to contract, and all the animal functions are performed; this they denominated the animal spirits, and were of opinion that it was secreted from the blood by the brain. This secretion they supposed, like all the other secretions, could only be pure, when the blood from which it was formed was healthy and proper; and that the goodness and purity of this latter fluid depended on its being elaborated by healthy organs out of proper materials. Consequently, that good blood could never be formed out of an unwholesome diet, nor even out of the most wholesome food badly digested. This induced them to pay great attention to the state of the digestive organs, and to the diet of patients, and their observations led to these conclusions; 1st. That the half digested, or ill digested food, furnished a smaller proportion of good blood than nature required, but a large proportion of excrementitious, half digested matter: 2ndly. That some portion of this matter would be taken up by the lacteal vessels into the circulation, and deprave the blood, and consequently all the secretions, more or less: 3dly. That different kinds of humors resulted from this condition of the digestive organs; the principal of which, and the only one we have here to deal with, is the pituitous humor, of which they enumerated several kinds, and to the presence of which they attributed most of the diseases of the human body. That kind of Pituita, to which most of the ancient physicians attributed the production of Night-Mare and deranged sleep, was called the Pituita Acida, which was found to be generated in great abundance in the stomachs and intestines of all patients subject to Night-Mare: this was supposed to enter into the circulation, and to cause some derangement in the functions of the nerves and animal spirits, by obstructing the free motion of the latter, and rendering the former bad conductors. They had various opinions respecting the manner in which this obstruction was effected, and also as to the part where it took place; some making the brain the seat of this affection, others the lungs and diaphragm. But without entering into the merits of their respective theories, we shall pass on to their ideas of the indication of cure. I cannot however pass over this part of the subject without noticing Willis’s opinion of it, and the ingenious hypothesis by which he attempts to explain this difficult subject. There are few physicians who have left so splendid a monument of talents, learning, and industry, for the admiration of posterity, as Willis has done; and although an English physician, and flourishing in the British court, there is no country in Europe in which his works are less known and admired than in that in which they were published. In his work DE ANIMA BRUTORUM, of which no man will ever repent the reading, he treats of this disease in a distinct chapter, cap. vi. and places the seat of it in the cerebellum. The following short extract will give some idea of his hypothesis:

“Quamobrem Ephialtis paroxysmum induci putamus, quatenus inter dormiendum, una cum succo nerveo, materies quædam incongrua cerebello instillata, quæ spiritus in prima scaturigine torporem, sive narcosin quandam inducens, eos mox a functionum suarum muniis paululum cessare cogit, proinde ut ab altero velut lethargo intra cerebellum excitato, actiones vitales eclipsin brevem patiantur; qua durante, partim a præcordiorum obstrictorum lucta, partimque a sanguine in iis plurimum aggesto, et stagnante, gravamen istud, ac velut molis incumbentis, sensus infertur; deinde quoniam cæteræ omnes totius corporis facultates a cordis motu dependent, idcirco hoc impedito, et suppresso, illæ statim deliquia, aut inordinationes subeunt, præsertim vero quià sanguinis in cerebrum, pro spirituum animalium fomite, effluxus interrumpitur, propterea mox horum effluxus in systema nervosum supprimitur, adeo ut laborantes, dum pectoris molem imaginariam excutere satagunt, nec corpus nec membrum aliquod movere possint; nimirum quia spirituum (donec sanguinis affluxu destituuntur) irradiatio in partes motrices inhibetur: interim qui in cerebro resident, huc, illuc, lati, phantasmata confusa, et ex molestia a præcordiis impressa, horrenda spectorum insomnia concipiunt.”

It appears evident, from the mode of treatment to which this disease gives way, that the primary cause, in whatever manner it may act, has its seat in the digestive organs; nor can any difference, or even error, in explaining its modus agendi, in any manner invalidate this doctrine. The ancient physicians seem tolerably well to agree on this point, and consider Night-Mare as a species of epilepsy, arising from a superabundance of acid humor in the primæ viæ, and their treatment was entirely directed to the evacuation and correction of that humor. If they were mistaken in their pathological ideas of this affection, they were at all events successful in their treatment; and it was usually their practice to reason from the cure to the cause of a disease, a safe mode of reasoning in medicine. Experience had taught them that a long train of diseases originated from this cause, and a little observation will suffice to convince any man, unprejudiced by medical theories, that Night-Mare originates from no other cause than a defect in the digestive process, whereby the food, which should be converted into good chyle, is transformed into a half-digested mass of acid matter, which is productive of heart-burn, acid eructations, flatulence, and intolerable gripings, with the whole train of dyspeptic and hypochondriacal symptoms. There are many stomachs which convert every thing they receive instantly into an acid, and such will be generally found to be the case with persons subject to habitual Night-Mare, or frightful dreams, and disturbed sleep. Such stomachs too are frequently distended with some acid gas, and I have often found the paroxysm of Night-Mare to be the consequence of this distension alone, and to be immediately removed by any thing which would dispel the gas, such as a glass of peppermint cordial, or gin, or any carminative medicine. A medical gentleman in Norfolk, who laboured under an inveterate disease of the digestive organs for several years, which in the end proved fatal, was dreadfully tormented by the most pertinacious paroxysms of Night-Mare, which threatened suffocation, had recourse to a solution of Ammonia in warm water, which he always drank when the paroxysms of Night-Mare began to disturb him; for whenever they did begin, they always continued to torment him, every time he fell asleep. The success of this plan very far exceeded his expectations. The immediate effect of the medicine was to send up a great quantity of wind from the stomach, which was succeeded by a profuse perspiration, and tranquil, undisturbed sleep.

I have always found, in my own case, that Night-Mare was accompanied with distension of the stomach and bowels by flatus, constipation, and acid eructations.

In this state of things every thing which is eaten or drank becomes instantly acid; and even the saliva in the mouth, I have often observed to have an acid taste. I have made repeated inquiries of others who were habitually subject to Night-Mare, and have always found them to be complaining of the same symptoms, although they had no idea that these were any way connected with the disease in question. A closer examination into the state of my own health, soon convinced me that my Night-Mare, which was become so alarming as to induce the greatest fear of epilepsy, was altogether depending on the state of dyspepsia under which I was labouring, and which was always greatly increased by remaining at sea, until at length it incapacitated me for my duty; attacking me in the daytime, affecting my memory, and threatening the most serious consequences. Under these circumstances I was twice invalided, and on retiring into the country, in a few months recovered my health, so that the Night-Mare, which was before habitual, and made its attacks whenever I went to sleep, was now become in a measure accidental, and depending upon causes more within my command. It was still however very severe, and returned on the slightest degree of irregularity of living, and on going to sea again, became worse than ever, accompanied with severe palpitations of the heart, and great irregularity in the pulse. It was under these circumstances that I began first to pay attention to that acidifying principle which I found to exist in the organs of digestion, and to try upon myself the effects of those remedies which have proved so successful in combating this monster, that has so long proved the enemy of my repose.

Observing the success of the Ammonia in the case which I have mentioned above, I had recourse to it myself in the same manner, but found it so disagreeable to the stomach, that it frequently produced vomiting. This indeed removed the tendency to Night-Mare, but it equally prevented my rest. I tried some of the other alkaline salts, but with no better success; the reason of which was, I believe, that I drank them dissolved in some cold liquor, upon an empty stomach, at the time that the disease was most troublesome to me, that is, early in the morning. Finding the stomach reject the alkalies in this simple form, I made a variety of attempts to render them palatable, and at length hit on the method of dissolving them in ale, or porter, and fixed on the Carbonate of Soda as the most agreeable of them. This experiment proved of more service to me than I expected; for I soon found it to be, not a nauseous draught, like the aqueous solution, but a delicious beverage, which I could drink with great pleasure; for the porter or ale, which is generally greatly inclining to acidity, was much benefited and improved by it. The carbonate of soda becomes partially decomposed by the acid of the liquor, and parts with a great portion of its carbonic acid gas, which causes the liquor to foam up, and imparts to it the appearance and flavour of bottled porter or ale. Having thus ameliorated the malt liquor itself, I grew fond of it, and drank as much every day as would receive about a drachm of the carbonate of soda, only at my meals; but whenever I found that sense of oppression about the præcordia which indicated the predisposition to Night-Mare, I had immediate recourse to a large dose of the soda, and always obtained relief. This salt not only corrects the acidity in the primæ viæ, but likewise brings away by stool a quantity of viscid slimy matter, so acrid, as to burn and excoriate the parts as it passes out. As I constantly persisted in the use of this alkaline salt, and got rid of this trash from the body, my appetite, which had long been lost and depraved, returned, and the digestive organs performed their functions again with ease and success. But still the propensity to acidifying remains, and a cautious attention to diet, and to the evacuations is always necessary. By perseverance in a plan founded on these principles, I found my enemy at length subdued, and brought under a degree of control which I had never hoped to obtain, and this circumstance has induced me to give to the world, (and more particularly to those labouring under the same disease,) my opinions and advice. By a close attention to the latter, I do not doubt but they will succeed in driving from their couch this fiend of night, this enemy of repose.

A small work was published on this subject about half a century ago by Bond, who places his principal dependence for cure on blood-letting. I do not deny but there are subjects in whom this remedy might be admissible, and perhaps advantageous; but I do not doubt, at the same time, that in far the greatest number of persons habitually affected with this disease, it would add fresh vigour to the monster, while it drains the vital powers of the struggling patient, and increases his danger. Bond carried this practice to a great length in his own person, but did not cure the disease. It is at best but a doubtful and a dangerous remedy. To those persons who are only occasionally subject to it, and who are generally most alarmed at it, as the disease comes upon them unexpectedly, and without their being always able to assign any cause for it, it appears difficult to apply a remedy, as the mischief is generally over before they are aware of its approach. A little attention however to the state of the digestive organs will generally point out to them, that it was connected with indigestion, flatulence, or costiveness; or perhaps all these together: frequently it is the consequence of having eaten some particular kind of food, which experience shews always to disagree with the stomach. There are certain kinds of food which will constantly produce this disease in such as are at all liable to it. Hildesheim, in his Spiceleg. De Affectibus Capitis, says: Qui scire cupit, quid sit Incubus? is ante somnum comedat castaneas, et superbibat vinum fæculentum. “He who wishes to know what Night-Mare is, let him eat chestnuts before going to sleep, and drink after them feculent wine.” I found by experience in the West Indies, that eating a particular fruit, called the alligator pear, would at any time of the day produce Night-Mare. This is a pulpy fruit, which, when cut into, resembles a custard, and is frequently spread upon bread, and eaten instead of butter, whence it has obtained amongst military men the name of subaltern’s butter, and it is certainly no contemptible substitute for fresh butter. I used frequently to eat it beat up with the juice of Seville oranges and sugar, in which case its action was almost instantaneous. So great a propensity to sleep came upon me, that I could not resist the temptation, though well aware of the consequences; so that I generally kept some person by me to awake me as soon as the Night-Mare came on, which was always in the course of a few minutes. I have frequently shewn this experiment to my medical friends, as I have hinted above. The articles most likely in this country to produce Night-Mare, I conceive to be cucumbers, nuts, apples, and all such things as generally produce flatulence. Whenever a person has discovered the offending article, it is certainly prudent to abstain from it, more especially in the evening. If however that state of stomach and bowels which gives rise to Night-Mare, should be perceived, there will be just reason to apprehend that it will occur, and it will be advisable to have recourse to some preventative. The paroxysm of Night-Mare does not always immediately follow the eating any improper food, b℥ut sometimes several days elapse before its attack. In this case it is easier to foresee, and consequently to prevent it. The signs by which its approach may be known, are unusual drowsiness, disagreeable dreams, and disturbed sleep, with wind in the stomach and bowels. In this case I would recommend immediate recourse to be had to the carbonate of soda, as I have described above, or to the following draught, which may be taken at bedtime.