The appetite of sleep.—The Physiology of sleep.—Etiology of insomnia.—Symptomatic insomnia.—Intrinsic insomnia.—Varieties of intrinsic insomnia.—Psychic insomnia.—Emotional shock and prolonged mental strain as causes of insomnia.—The nervous temperament.—Symptoms of intrinsic insomnia.—Toxic insomnia.—Insomnia from tobacco.—Alcoholic insomnia.—Insomnia from tea or from coffee.—Gouty insomnia.—Senile insomnia.

The important subject of insomnia has engaged my attention for a long time. In 1878 I delivered a clinical lecture on the causes and cure of insomnia to the students of the Birmingham Medical School, in the Queen’s Hospital, and the matter of this discourse was afterwards further published in The Lancet, on June 15th and 22nd of that year. This lecture I revised and rewrote entirely afterwards, embodying in it some additions from my later experience in practice, and, so enlarged, it was included in each of the two editions, of 1886 and 1891, of my “Contributions to Practical Medicine.” In the autumn of the year 1900, I reviewed the subject again in two clinical lectures which I gave at my hospital, and these were issued in print in The British Medical Journal, on December 1st and 8th, 1900. These last lectures, in which I have tried to bring their subject up to a point at least abreast of our latest knowledge in the principles and practice of medicine, I have revised and rewritten; and I have amplified them, especially in their therapeutic parts. So rewrought, they form the contents of the following essay. This work, done as to the causes and cure of insomnia, that is, done as to particular diagnostic and therapeutic efforts in which the skill of the physician and the resources of our art are often taxed severely, in the intricacies of a difficult, delicate, and abstruse subject, I have tried to accomplish in the spirit of the Baconian philosophy, in the spirit of that aphorism of Bacon which Sydenham prefixed to his renowned “Tractatus de Podagra et Hydrope,” namely, “Non fingendum aut excogitandum, sed inveniendum, quid Natura faciat, aut ferat.” The result of my pleasant labours I venture now to offer to the judgment of my profession. My lectures on insomnia were delivered for the instruction of medical students in my clinical class; they are further published in these pages in the hope that they may help my medical readers in practice. In view of the conditions of the original delivery of these utterances, I have decided, in revising them, to preserve their colloquial style. Furthermore, in preparation for this present publication of these lectures, (1904,) I have revised them again, and made some additions to the therapeutics of my subject.

Sleep is a function of life, and life, in some sense, may be said to be a function of sleep, in man, in the animals which are a little lower than he is, in some sort in plants, in everything which lives. The living organism which cannot sleep cannot live. For all beings endowed with the crowning mercy of consciousness sleep is a pleasure as well as an appetite, and it is a necessity as well as both. For these conscious beings, strung as they are in their sentience to the most exquisite responses in the world’s vast chorus of living harmonies, sleep is indeed and in truth “tired nature’s sweet restorer.” For man, at the head of such beings, and perhaps the only of them which knows the cark of a mind’s unrepose, or the wear of “that unrest which men miscall delight,” sleep it is indeed which smoothes out life’s fretting creases and “knits up the ravelled sleeve of care.” That you may become practitioners of medicine you are students in this place of the manifold sciences of medicine in some of their chief practical bearings, mingled with the inexorable simplicities and with the endless intricacies of the art of healing. You are clinical students here of that cherished art of ours, an art which is of men philanthropic and of time perennial, as its lovely figure stands revealed in all its subtle and splendid details, firm and broad based upon the blended foundations of its great constituent sciences. You are students in this hospital I love of that great art of ours in clinical medicine, in its concrete application to individual cases of human suffering, no two of them indeed ever quite identical, no more than are identical a tree’s waving leaves or the billows of the rolling sea. Let us press forward together, in all the absorbing zest of the pursuit which is ours, to the brightest understanding which yet there may be of the intimate nature of sleep. Let us collect, discriminate and sort the causes which make for insomnia. Let us sift and sum up all which our sciences and our art, our experience, and even our empiricism, of which last I am not ashamed, have of tried adoption for its cure. In this work your physiological training, your clinical insight, your utilitarian aim, and even your poetic fancy and your literary culture, may all find coördinated play, in the comprehension and in the verbal depiction of functions and maladies which are intricate with our lives, associate with our highest attributes, and woven in woof and warp into the very texture of all our pains and of all our pleasures.

Favoured by your kind attention, I purpose to offer you some considerations upon the vital function of sleep, and upon the conditions, causes, and cure of insomnia, based upon a somewhat long and successful experience of those subjects in practice, as a physician. These subjects are certainly of first-rate importance in relation to our knowledge of the science and our practice of the art of medicine. Possibly you may scarcely be able to appreciate their relative importance while you are, as yet, only hospital students. Later in your careers, when you become engaged in actual practice among the sick, and especially when you take part in what is called private practice, often will you be confronted by the perplexities of insomnia, and often will your pleasant duty lie in successfully unravelling the causes of sleeplessness, on that soundest principle of causation and of therapeutics, cessante causâ cessat et effectus, and in curing insomnia by counteracting those causes, and by making their tiresome and diresome effects to cease. I hope to be able to show you that in such happy results the science and the art of the physician may play a successful part. Like thirst and like hunger, sleep is an appetite. We may define an appetite, in the words of the philosopher Bain, to be a craving produced by the recurring wants and necessities of our bodily or organic life.⁠[2] An appetite, strictly so-called, has two characteristic marks, and these marks are strikingly characteristic of sleep; these marks are two conditions which are true to sleep—namely, its periodic recurrence and its organic necessity. We know that the natural course of a human life brings on sleep without the volition of the individual willing the event. The true character of sleep as a veritable appetite appears when it is resisted. Under such resistance the individual person experiences what is called, in metaphysical parlance, a “massive” form of uneasiness, discomfort, and pain. The will of the individual, in the presence of this uneasiness, is energetically urged to remove such discomfort and unrest, and is urged from pain towards pleasure, is urged to obtain the gratification of relief in what Bain called “the corresponding voluminous pleasure of falling asleep.”⁠[3] In this imperatively urgent volitional impulse is the appetite of sleep. Sleep is a desire; with the further characteristics of its organic necessity, and its periodic recurrence, it ranks as one of our appetites.

The intimate physiology of sleep is a difficult subject, and the difficulties of its explanations have been the topics of much controversy, and such controversy appears to have issued from various combinations of the teachings of observation, of experiment, and of analogical and other reasoning, upon the phenomena of sleep. I do not propose to follow at length the details of this part of our subject. As a clinical teacher I must not overload your memories, but rather must I try to make easy your mental digestion. For our practical purposes I think we may understand that two distinct, but associated and related, vital changes occur in sleep. The one is some intrinsic change in those ultimate tissue elements of the brain which are concerned in consciousness; the other and “coarser” change is a diminished supply of blood to the brain, and especially to the blood vessels of the cortex of that organ. The former change is at present undemonstrable, excepting by inferential reasoning. Perhaps there is some essential and intrinsic change in the brain, and perhaps there also is some such change in the spinal cord and ganglionic nervous system, both of rhythmic occurrence, and both conditions of healthy sleep. Perhaps there is a functional depression of these parts in sleep, and especially of the cerebral cells, arising from “an accumulation in and around them,” as Sir Thomas Lauder Brunton puts the matter as to the cerebral cells in sleep, of some of the products of normal tissue waste. Perhaps for normal sleep an intrinsic change of this kind must gain the wide distribution I have mentioned. It is likely that there is in sleep a rhythmic change such as I have indicated, and that this change is sustained by the physiological effects of some of the issuants of those tissue changes, muscular and nervous, which especially occur in the active waking state of the body.

Perhaps for our sleep we must drown our cerebral cells in a kind of auto-intoxication with the ashes of our waking fires. We may usefully recall this view of the subject when we use exercise and fatigue as remedies for insomnia. The proof of the other broad change in sleep—namely, diminished blood supply to the brain, and especially to its cortex, rests on inference from physiological analogies, on various observations, and on the solid basis of direct experimental evidence. We must note, however, that the human brain, in its perceptive, cogitative, and volitional functions, in these great divisions of consciousness, is not the only part which sleeps. The whole living body sleeps. The changes which the event of sleep declares certainly extend beyond mere loss of consciousness; they extend to secretion, to the action of the heart and blood vessels in the general circulation of the blood, to respiration, to “reflexes,” and so extend to all the tissue modifications, and to all the other vital activities, upon which such manifold transitions depend. In order to complete your precognitions of the physiology of sleep, before we pass on to consider the several conditions of insomnia and their appropriate therapeutics, I may refer your attention to the admirable accounts of these subjects to be found in the text-books of Dr. Augustus Waller⁠[4] and of Sir Michael Foster.⁠[5] From each of these volumes I offer a brief quotation, which sufficiently illustrates our subject for my present purpose. On that part of his subject which is so important to us from a therapeutical standpoint—namely, the state of the cerebral circulation during sleep, Dr. Waller says:

“Although there is no doubt that in coma—a pathological state similar in some respects to physiological sleep—the cerebral vessels are congested, the observations of Durham on the exposed cerebrum of sleeping dogs, and of Jackson on the retinal vessels of sleeping infants, are to the effect that vessels shrink in sleep, and we may therefore feel reasonably assured that the sleeping brain, in common with other resting organs, receives less blood than in its state of activity. Moreover, Mosso’s investigations on exposed human brains afford evidence that the organ becomes more vascular during mental activity....”

That sleep concerns the whole body, and not the brain alone, is well put by Sir Michael Foster. He says:

“Though the phenomena of sleep are largely confined to the central nervous system, and especially to the cerebral hemispheres, the whole body shares in the condition. The pulse and breathing are slower; the intestine, the bladder, and other internal muscular mechanisms are more or less at rest, and the secreting organs are less active, some apparently being wholly quiescent; the secretion of mucus attending a nasal catarrh is largely diminished during slumber, and the sleeper on waking rubs his eyes to bring back to his conjunctiva the needed moisture. The output of carbonic acid, and the intake of oxygen, especially the former, is lessened; the urine is less abundant, and the urea falls. Indeed, the whole metabolism and the dependent temperature of the body are lowered; but we cannot say at present how far these are the indirect results of the condition of the nervous system, or how far they indicate a partial slumbering of the several tissues.”

You may find an interesting and instructive employment if you follow Sir Michael Foster through his discussion of the exact state of the body, and especially of the brain, in sleep. He points out, what is now generally accepted, that an alteration of the cerebral circulation is not the whole of sleep. He judges that “the essence of the condition is rather to be sought in purely molecular changes,” and then he goes on to suggest a resemblance between the systole and diastole of the heart and the sleeping and waking of the brain; and then he dwells on the various periodicities which may be observed in the activities of the human body, and even suggests that the fundamental rhythm of the heart may be a reflection of the mysterious cycles of the universe, while it may yet be only the result of the inherent vibrations of the molecules of its own proper structure.

If we exclude from our consideration the insomnia which is a concomitant of some forms of unsoundness of mind, and which kind of insomnia I do not propose to deal with in these lectures, you will find that absent or imperfect sleep, inability to sleep at all, or at a convenient time, or long enough, without the aid of drugs, is a frequent consequence or complication of numerous and varied conditions of disease. Etiology, as you know, is that division of the science of medicine which has to do with the causes of disease. The etiology of insomnia embraces the enumeration of all the causes of the malady. These causes are numerous, and a classification of the varieties of insomnia, upon the basis of their causal distinctions, is somewhat difficult. Let me recommend to you, for use in practice, the following classification of the varieties of sleeplessness under our consideration. It is the best etiological arrangement I can form, of the causal intricacies of our subject. It is a classification which you will find of service clinically, when you pursue the discovery of the particular causation of any given case of sleeplessness. Cases of insomnia seem to divide themselves naturally into two groups, namely, of cases of what may be called symptomatic insomnia, and of cases of what may be called intrinsic insomnia. Symptomatic insomnia attends a vast variety of morbid states, and is secondary to them, or is part of them. Intrinsic insomnia, as we shall see later on, is capable of distinct definition, and it breaks up naturally and simply into three smaller divisions, upon a causal principle of division.

As to symptomatic insomnia, pain, if severe enough, and from whatever cause arising; pyrexial elevation of temperature; frequent coughing, such as often occurs in pulmonary consumption; dyspnœa, such, for instance, as results from obstructive dilatation of the cardiac cavities, and appears to require an extraordinary vigilance of the nervous centres for the maintenance of the vital processes of respiration and circulation—are clinical conditions of disease which may prevent, shorten, or break up sleep. Such conditions are frequently met with in medical practice, as single causes of insomnia, or as conjoint causes of it in various combinations. In such and in similar instances the cause of the sleeplessness is obvious, and the consequential character of the insomnia—that is, its dependence upon a distinct and sufficient cause—is clear. For the therapeutic control of this kind of insomnia we may employ with success one of two curative methods, or we may employ a judicious combination of these methods, such combination being founded upon a skilled appreciation of the especial needs of each individual case. We may control sleeplessness of the kind in question either by the exhibition of remedies which directly cause sleep, that is to say, by the administration of some of the drugs which we know as hypnotics or soporifics, or we may control it by the employment of measures which combat the cause of the insomnia, by removing pain, by reducing the heat of fever, by quelling cough, by relieving cardiac disturbance and dyspnœal discomfort, and so on; or by using in conjunction hypnotics and remedies addressed to the removal of the cause of the sleeplessness. In such cases of symptomatic insomnia, as in medical practice generally, you will find that it is convenient to your duties, and that it tends to the thoroughness of your ministrations, if you regard the therapeutic indications of each case from the well-known standpoints, respectively, of the indicatio causalis, of the indicatio morbi, and of the indicatio symptomatica. By a judicious combination of the remedies so suggested you will be able to deal successfully with cases of symptomatic insomnia. By regarding the cause of the illness with which you have to deal as a medical attendant, by regarding the various pathological processes which underlie the progress of that illness, and by regarding the symptoms of that illness, by regarding these points in turn, or together, or in various combinations, with a judicious therapeutic intention, you may arrange your remedial efforts upon a systematic and comprehensive basis.

Now let us consider the details of intrinsic insomnia. There is a simple inability to sleep, which you will often be required to cure—a kind of insomnia which may be called for the sake of simplicity, but perhaps scarcely with strict truth, insomnia per se. This is a kind of wakefulness for which we cannot discover an objective or obvious physical cause; it is a kind of wakefulness which seems to depend upon an inability of the brain and nervous system generally to adapt themselves to the conditions which are necessary for sleep. We meet with this disorder more in private than in hospital practice. It occurs mostly in persons who are members of what are known as the upper and upper middle classes. It occurs mostly in persons of high mental endowment and of neurotic temperament. The malady is of extreme importance, and, happily, if its causes be understood and judiciously corrected and controlled, there are few affections which are more within the sphere of curative therapeutics. I think I can succeed in showing you how to unravel the complex causes and discover the successful treatment of this kind of insomnia.

The causes and the course of particular instances of intrinsic insomnia present some striking differences. You must know these differences, and be ready to recognise them, for the knowledge of them clears up alike the therapeutics, the successful treatment, and the prognosis of individual cases of the malady. I have found it to be convenient in practice to arrange the different clinical varieties of such insomnia into groups, in which the cause of the affection is the principle of division. These groups I call respectively the psychic, the toxic, and the senile. Let us see how these divisions work out in detail.

The brain in natural sleep is, as we have seen, relatively anæmic. The cerebral arteries, as we have seen, are more filled with blood than during sleep, when the brain is in full waking and working activity. When thought is active, the parts of the brain concerned are living relatively rapidly; they are actively receiving nourishment from the blood, and they are, too, actively ridding themselves of the waste products of their vitality. In sound natural sleep the brain is inactive, excepting those parts of it which are concerned in the processes of organic life. In sleep the blood flows to and through the brain in streams which are smaller and gentler than in the waking state. The cells concerned in thought, volition, and feeling are not expending energy, they are renewing it and storing it—they are resting. Any cause, however little we may be able to trace the details of its operation, which directly prevents a repose duly deep of a sufficient number of those brain cells which are the organs of conscious thought, will render sleep impossible; relative cerebral hyperæmia is an inseparable consequence of such activity, and such relative cerebral hyperæmia becomes a concurrent, but subordinate, cause of insomnia. Here there is progression through a vicious circle of two terms, in which the impulse of the morbid movement springs from the cerebral cells. So we see that there are causes of insomnia which we may fairly regard as acting primarily in sustaining cerebral activity, and with it, and in consequence of it, relative cerebral hyperæmia, which hyperæmia becomes a contributory cause of the cells keeping awake.

In some other cases of intrinsic insomnia I think we may regard the malady as arising primarily in a perversion of the cerebral blood supply. Any cause which prevents the brain from becoming relatively anæmic in a sufficient degree for sleep will produce sleeplessness. Any ingested agent which sustains cerebral hyperæmia, or any pathological change which impairs sufficiently the contractility of the smaller cerebral arteries, may prevent wholly, or in part, the occurrence of such a degree and extent of cerebral anæmia as is required for the production of sleep, and without which sleep cannot be.

So there are causes of insomnia which act primarily in exciting and in sustaining a relative cerebral hyperæmia, and with it, and in consequence of it a cerebral activity which is wakeful. Here there is again a progression through a vicious circle of two terms, but one in which the impulse of the morbid movement springs from the cerebral blood vessels. In conscious cerebral activity, which, as we have seen, is a complex condition of at least dual causation, in which thought certainly implies increased blood flow, and increased blood flow sustains thought, perhaps it may be considered that we cannot, with strict accuracy, allow initiative precedence to either of the causes which are essential to the common result. In medical reasoning there is little which is so difficult as tracing effects up to their causes, and there is little so easy as the invention of causes for effects. Let this caution make you wary. Take due pains in practice to analyse the causation of each particular case of intrinsic insomnia. When you make such analysis you will find that in some cases of sleeplessness, as in the psychic group, undue and protracted cerebral activity is the primary vice, and that in others, as in the toxic and senile varieties, relative cerebral hyperæmia is the initial error, and wakeful cerebral action its direct consequence.

Our present consideration of our subject has advanced to a point at which we may usefully illustrate our generalizations with some sketches of particular instances of intrinsic insomnia, as they are met with in medical practice. In a case of psychic insomnia some sudden emotional shock of a depressing kind, as grief at the death of a beloved relative, will sometimes be found to have produced at once persistent sleeplessness, which sleeplessness will only yield to carefully directed therapeutic procedures. Again, prolonged mental strain, in all its varied phases, is a common cause of the psychic variety of insomnia. Our patient may be a student preparing for an examination. For weeks, in spite of fatigue, he may have shortened his hours for sleep that he might lengthen his time for reading; and he may have been in the habit of keeping himself awake, when he could have readily fallen asleep, by drinking strong tea or coffee, or by smoking tobacco. But he could always go to sleep at once when he went to bed, and sleep soundly, until, after some weeks of his abnormal work, with the nearer approach of the examination bringing increased anxiety as to the result of the ordeal, he found he began to sleep badly or almost not to sleep at all. He grew miserable; he could not remember what he read; he felt unfit for any exertion; and he could not face his examination. Or, our patient may be a young professional man. He has commenced practice, or rather to wait for practice, as a barrister, a solicitor, a physician, or a surgeon. He begins to find that causes or cases have not been waiting for his advent; clients or patients are “few and far between.” For a time he manfully struggles on, his hope and his health sustaining him; but these at last yield under the continued pressure of new disappointments and accumulating anxieties. He may want money; his friends will give it to him readily if he will ask for it, but his pride prevents him. It is not a gift or a loan he needs; he does not want to beg or to borrow money; he yearns to earn it. And while he has been hoping and waiting, and growing sick with the failure of his expectations, he has been working early and late in his exacting studies—perhaps straining his powers in preparation for some higher examination, and, it may be withal, adding the denial of due sleep and exercise, and so he has been wasting and wearing his psychical and physical energies, in the trust that he might thus so skill himself the more as to secure the longed-for practice. At last he has fairly broken down. He has grown thinner; he looks haggard; he is filled with groundless fears; he is weighed down with the ineffable misery of insomnia; he has headache constantly, and noises in his ears; he thinks his memory is failing; he is dull and listless; he has been lying awake for hours after going to bed, or, waking in the “small hours,” he has been unable to sleep again, and when he has slept he has had horrid dreams; and he comes to us for help because he can scarcely sleep at all, and he is possessed by the fear that he is going mad. His misery is urgent; it excludes all other joys and most other pains; it is the unspeakable misery of intrinsic insomnia, the insomnia which hangs on no solacing peg of causal pain. Here we observe particular instances in which acute or continued mental strain is the primary cause of the sleeplessness. Where the shock has been sudden and severe it has been sufficient to rouse a given group of cells into persistent activity, and to produce psychic insomnia suddenly. So produced, the sleeplessness may become a persistent trouble, which yields only to judicious therapeutic procedures. In other cases, and more commonly, the insomnia has only arisen after prolonged mental strain, as that which a student may undergo in over-reading for an examination, as that of continued financial anxiety, or that of arduous and sustained literary composition. Where the shock has been sudden and severe enough, there has resulted a persistent wakeful activity. Where the strain has been less intense, but kept up long, a monotonous group of ideas has been maintained in exhausting recurrence. In either case it would appear that sleeplessness did not occur until there arose from exhaustion partial or complete vasomotor paralysis of the intra-cranial blood vessels; it arose when the arterioles of the brain had no longer that contractility without which sleep is impossible. In these forms of insomnia unnatural excitation of the cerebral cells is probably the initial fault. This point of view, we shall find just now, gives the best working hypothesis for our treatment.

Here I must further direct your attention to the question of the causal association of what is known as the nervous temperament with intrinsic insomnia, and especially with this psychic variety of the malady. In my experience, the subjects of the psychic variety of insomnia are mostly men, and almost invariably men of the temperament which is known in medicine as the nervous temperament. I advise you to study temperaments. Their recognition is of much value in diagnosis, in prognosis, and in therapeutics. A temperament may be defined as “that individual peculiarity of physical organisation by which the manner of acting, feeling, and thinking of every person is permanently affected,” and the nervous temperament is marked by great sensitiveness and activity of the nervous system.⁠[6] We have lately been too ready to ignore temperaments; our fathers studied them better and regarded them more than we do. But I shall not go to any authority for a portrait of the nervous temperament; I shall describe it to you as I judge I have found it in a physician’s practice. I use the phrase nervous temperament to indicate a distinct type of outward form, of manner, of habits, of tendencies, and of personal aptitudes, physiological and pathological. Temperaments present their various types most frequently in men. Comparatively few women exhibit a well-marked temperament; but when a woman is of the nervous temperament, in her the temperament is mostly very distinct indeed. In frequent instances, two or more of the different kinds of temperament may appear to be blended in one patient; we have a compound of reciprocally modified temperaments.⁠[7] A man of distinctly nervous temperament has a quick manner; he is nearly always in a hurry; he is apt to talk volubly and to eat quickly; if he does not know us well, he fidgets in his hands, or legs, or face when he is speaking; he talks abruptly, earnestly, and fluently, often splitting up his phrases, or recalling and correcting them, and especially modifying qualifying words, such as adverbs and adjectives, in his anxious desire to express what he conceives to be the finest shades of truth. A man of this temperament is apt to “overdo” everything into which his feelings enter, and his feelings enter prominently into most of his doings. He is apt for hobbies; and he is often a diligent collector of curiosities. When he becomes a patient, he is harassed about some trivial symptom; he has felt his heart beating, and he thereupon fancies he has some deadly cardiac disease; he thinks his memory is failing, and he forthwith imagines he is going mad. Your elucidation of temperamental details in medical practice will develop your clinical observation and acumen. Ars medici est in observationibus is a maxim of our schools which was a favourite one of that excellent clinician and successful physician, the late Sir Andrew Clark, and this proverb of ours is very true in the detection of the signs of the nervous temperament.

A man who has suffered much from intrinsic insomnia becomes the subject of a well-marked group of symptoms, subjective and objective. Most of them are given by certain writers amongst the signs of cerebral hyperæmia. It is probable that they mark a particular variety of exhaustion of the brain, attended by more or less of an abnormal increase of blood in the brain, and accompanied by some general prostration of the bodily powers. These concomitants of insomnia, as I have found them, I now describe to you. The patient has a dull and listless look; his eyes are wanting in vivacity; the upper lids may droop a little, and they may be slightly swollen. The complexion is sallow. There is headache; of this there are two kinds, which either co-exist or occur separately. The commoner variety of headache is a dull pain felt over the whole of the vertex, together with a vague and widespread feeling of oppression in the head; the other is a sharp, shooting pain, which comes on suddenly, and usually in single flashes, and which gives the idea of a knife being driven through the head from one temple to the other. Occasionally the patient feels giddiness momentarily; this may cause a false step, but it never lasts long enough to give rise to staggering. The skin of the scalp, especially near the sagittal suture, may be tender. There are noises in the ears, in one or in both, usually of a low-pitched whistling character. This tinnitus aurium may come on suddenly, and without apparent cause, as when the patient is talking quietly, or it may only arise when the patient’s attention is more closely occupied, as in writing a letter or in casting up figures. A striking sign in the group of symptoms we are considering is a slight impairment of hearing. The patient may be unaware of it, but those with whom he lives have noticed that he often asks them to repeat what they say to him because he could not quite catch their words. He may also complain of seeing spots before his eyes—little cobwebby black lines, muscæ volitantes, which come and go and float about, or, perhaps, bright, bluish, phosphorescent-like specks, phosphenes, which seem fixed for a moment, one before each eye, and which only appear when he first directs his eyes towards an object. There are usually some abnormal sensations in the skin; not formication, such as is apt to arise in organic nervous disease, but a sharp, transitory, and isolated prickling, as of the movement of a single pin, which lasts only for an instant, and affects either the limbs or the trunk, mostly the former. There may be a peculiar twitching of muscles. This is a state of involuntary muscular movement of which I have made original and independent observation, and of which I know of no previous description, either oral or written. It is not a vibratory tremor, like that of progressive muscular atrophy, nor is it a contraction of a whole muscle, or of a group of muscles, such as arises in true convulsion. But, while the patient is sitting still, a considerable part of a muscle becomes the subject of rapid clonic movements, and these are wholly independent of his volition. These movements mostly occur in one of the lower extremities, and they are rarely sufficient to move the position of the limb; they usually affect the lower part of one vastus internus, and last for about a minute. The patient can feel the movements by attending to the affected part, and he can also feel that the muscle moves by applying his hand to it. In such a case there is often also an unnatural and painful sensitiveness to external impressions. The patient craves for quiet. A bright light troubles him. Noises, the sight of moving objects, touches, as of the hand of a friend upon his shoulder, annoy him. There is not an increased sensitiveness to external impressions, but impressions which are enjoyed or unnoticed in health become irritants.

In the toxic variety of intrinsic insomnia the cause of the sleeplessness acts primarily upon the blood vessels of the brain, giving rise to some degree of arterial hyperæmia. Cerebral vascularity, especially the arterial supply of the cortex of the brain, is maintained at such a height and so long by some poisonous agent that conscious cerebral activity—that is, wakefulness—is an inevitable consequence. Such a poison may be introduced into the body from without, or it may be a product of diseased processes arising within the body itself. Of course, I use the word “poison” in a restricted sense; I do not mean something which kills, but only something which produces abnormal manifestations in the living body. The poisons with which we have here to do are not lethal poisons, but milder noxious agents which produce certain distinct and abnormal manifestations. Tobacco, alcohol, tea and coffee are the external poisons which most frequently cause sleeplessness; internal or autogenetic poisons causing intrinsic insomnia may be found in certain waste products of tissue metamorphosis which accumulate in the bodies of gouty persons, or in the bodies of persons whose kidneys are inadequate.

Possibly, as our knowledge of auto-intoxication shall increase, some other forms of auto-intoxication may be found to cause intrinsic insomnia, and the exact details of the causal chain may be made out. Clinical experience has suggested to me that insomnia may sometimes be a neurosis having its origin in toxic absorptions by the gastro-intestinal mucous tract. Certainly intrinsic insomnia is found in practice to come and go with constipation and the relief of constipation. The explanation of such association of symptoms may be a toxic one. The word “copræmia” is coming into medical use, to signify a kind of poisoning of the blood by noxious principles derived from retained fæces. Sallowness of the skin, what may be called fæcal anæmia, anorexia, “biliousness,” and asthenia mark this condition, and, in some cases, intrinsic insomnia may be added to its characteristics.

With regard to the smoking of tobacco, many a man cannot sleep either sufficiently or soundly simply because he smokes excessively. Smokers often find by their own experience that they sleep badly if they smoke more than their usual quantity of tobacco, or if they smoke tobacco of a stronger kind than that to which they are accustomed. So a smoker who suffers from insomnia may find the cure of his sleeplessness in the restriction of his smoking. He need not give up, nor shorten, nor change his work, nor need he change his “surroundings”; if he restrict his smoking, he soon sleeps well. So also as to snuff-taking in relation to insomnia. Men of nervous temperament, or men into whose temperament there enters a distinct and considerable blending of the nervous element, often smoke tobacco or take snuff largely. The consumption of tobacco by smoking or snuff-taking stimulates the cerebral circulation. This stimulation, if pushed to undue limits, induces cerebral vasomotor debility, with a consequent tendency to persistent conscious thought, and so to wakefulness.

Similarly, too, the drinking of alcoholic beverages causes insomnia. The man who drinks to commencing drunkenness mostly sleeps soundly, if not well. But many a so-called moderate drinker knows that he sleeps badly if he take a little more than his usual quantity of wine, for instance, after dinner, or even his usual quantity of some unusual wine. Alcohol, when it passes from the stomach to the blood, flushes and dilates the smaller blood vessels, especially those of the brain; if such a condition be maintained, sleep is disturbed or wanting. We have all seen clinical examples of the insomnia of delirium tremens: the patient cannot sleep because the lesser arteries of his brain are weakened, perhaps paralysed, by alcohol, and sleepless cerebral activity is the inevitable consequence. Far short of what is usually called alcoholism, we often meet with cases of insomnia in which alcohol alone is the cause of shortened, interrupted, and disturbed sleep. The patient may pride himself upon his moderate use of fermented stimulants, and he may be wholly ignorant of the cause of the sleeplessness for which he consults us. We fail to find any sufficient psychic cause for his insomnia; but if we take away or diminish his wine or his grog, or induce him to consume it before the evening, we find he soon begins to sleep well.

Again, the effects of the consumption of tea and coffee in causing sleeplessness are well known. This effect is so obvious that patients usually remedy it for themselves. As you well know, tea in the form of an infusion and coffee in the form of an infusion or of a decoction are used generally in civilised countries as the daily beverages of the people. Tea leaves contain an alkaloid which has been called theine, and coffee seeds contain an alkaloid which has been called caffeine, and theine and caffeine have been shown to be identical; both these leaves and these seeds contain besides certain oily principles. With regard to tea, what may be called its physiological action appears to depend on the joint action of its theine and of the volatile oil which tea leaves contain. What is called green tea is produced by drying the fresh leaves on a heated iron plate until they become shrivelled; while black tea is manufactured by placing the leaves in heaps and allowing them so to lie while they undergo a kind of fermentation, after which they are dried. Green tea and black tea are powerful cerebral stimulants, exciting the mental faculties and the cerebral circulation, and tending to prevent sleep. Coffee, too, is a cerebral stimulant and antisoporific. It is sometimes used in medicine for these properties, to counteract the effects of opium and of its derivative narcotics, and of other narcotic poisons. Some people are extremely susceptible to the sleep-preventing effects of tea or of coffee; others, by use, do not feel such effects, even when considerable quantities of those beverages are consumed. In all cases of bad sleeping you should make sure that tea or coffee is not taken to excess, neither near bedtime.

In gouty persons, quite apart from secondary wakefulness caused by their gouty pains, there may be some intrinsic insomnia, of a kind which is probably toxic in its causation. So, also, intrinsic insomnia may afflict a patient whose kidneys are failing, who has renal inadequacy. In such cases it would seem to appear that the accumulation in the blood, in consequence of deficient excretion, of the products of tissue-metamorphosis causes a general restlessness which disposes to insomnia. Insomnia so caused is not severe, and it is rarely complete. There is slumber rather than sleep. There is restlessness, perhaps some excessive irritability to certain external impressions, short and broken sleep, and what may be called superficial sleep, rather than prolonged wakefulness. In this connection I may remind you that you should observe the tension of your patient’s pulse. A patient may complain that he sleeps very badly, that he lies in bed awake for some hours and has great difficulty in “getting off” to sleep, that he sleeps lightly, awakens often, and dreams much. You may find he has a pulse of increased and high tension, with accentuation of the aortic second sound, and with the cardiac first sound lengthened and muffled, perhaps reduplicated, at the apex of the heart. In a case of chronic kidney disease there may be also the physical signs which mark the characteristic cardiac hypertrophy which accompanies chronic contracting nephritis, and is an effect of it or a concurrent effect of a remoter pathological cause. Insomnia in such cases is likely to be due to the maintenance of a state of high tension in the cerebral arteries, the tension in them not falling sufficiently for prolonged, deep, and dreamless sleep. In practice you will find the causation of many of these cases of insomnia, and you will find sound therapeutic indications, too, in the signs of the gouty diathesis or in the discovery of albuminuria. Here I must give you a caution, which you may usefully remember in practice, namely, never accept a patient’s statement that he is gouty without the establishment by your own observation of facts sufficient for such a diagnosis. Insomnia which is purely nervous may be wrongly attributed to gout, and depletory measures of treatment may be adopted when corroborants are really indicated. The diagnosis of gout is a diagnosis for which patients often have a tender affection, and I am afraid it is a diagnosis which is often erroneously made, and wrongly handed on through a succession of credulous advisers. Do not fall into the frequent error of making a diagnosis of gout because a specimen of your patient’s urine which is brought to you shows a deposit which to the naked eye is like unto grains of cayenne pepper, and which deposit is made up of aggregated crystals of uric acid. Such a sediment may be only an innocent result of an acid fermentation, such as frequently arises in urine after its voidance, without any pathological significance whatsoever.

As I have already told you, there is a senile form of intrinsic insomnia. Remember that senility is a term of which the primary absoluteness is largely modified in particular cases by relative qualifications. Some persons are senile early, others only later. With much truth it may be said that a person is not as old as his years, at least in a pathological sense, but as old as his arteries. You may perhaps have observed amongst your friends that an exaggerated appreciation of the merits and value of early rising often increases as age advances. The broken and short sleep of many old persons is mainly, if not entirely, the result of senile degeneration of the smaller cerebral arteries. In such degeneration those blood vessels are less elastic and less contractile than in health, and a degenerative weakening of their walls often leads to their permanent dilatation; the smaller cerebral arteries, so changed by a pathological process, are physically unable, by reason of a diminution of their resilience and of their contractility, to adapt themselves normally to such a condition of relative arterial anæmia as is of the essence of healthy sleep. The tendency of this condition of the blood vessels of the brain to prevent, to lessen, or to interrupt sleep is probably to a great extent counteracted, in many cases, by the cardiac feebleness which so frequently, and which, within certain limits, it may be said fortunately, co-exists with senile vascular changes. When arteries are brittle, cardiac failure, within certain limits, may be regarded as a conservative lesion, in the sense that such failure tends to save from arterial rupture and the consequences of cerebral hemorrhage.