SLEEP. Orcus did the pious Æneas see the same twin | of many a once great intellect. It was noticed brethren seated when he visited Pluto's realm. only the other day in one of the giants of our Sleep was as godlike an agency to the nations own time, William Whewell. The death of each day's Whereas the metaphysician speaks of the soul of old as death itself. life it still seems to us, and men tread softly as quitting in dreams its earthly tenement, and and speak low in the presence of the dead, as wandering at its will, knowing no laws-the though they fear to wake them from their ever-physician looks on sleep as the rest, and the lasting rest. "It is that death by which we only rest, of the brain, of that portion of the may literally be said to die daily: a death brain wherein reside those functions which we All parts of our bodies rest at one which Adam died before his mortality: a death call mind. They rest whereby we live a middle and moderating point time or other: they can not always work, but for between death and life. In fine, so like death, their rest they need not all sleep. I dare not trust it without prayers, and an half- when not in active work, between their work, adieu unto the world, and take my farewell in some more, some less; but the brain proper, that is, the higher mental part thereof, rests only in a colloquy with God."* Passing from the theological, we come to a sleep. It may labor little, it may cease, as stage, where, if sleep be not a divinity, it never- many have to cease, from extreme toil; but it theless is supernatural, beyond the physical, only really rests and recruits itself for fresh metaphysical. Something which metaphysi- work when sleep is present: and so in many cians and psychologists have much pondered illnesses, in the fierce raving of delirium, in maand marveled at-something which they have niacal frenzy, and the wandering of fever, we hoped would explain the union of mind and know that sleep must come, or death. The othbody, and the disunion thereof: from which er parts of the bodily system, as of the nervous great men even of to-day think we may learn system, are at work during sleep, though with The heart beats slower, the the mind's independence of matter, its capacity slackened pace. of existence without matter, illustrated by all breath comes more quickly and less frequently; the wonderful phenomena of dreams. The long but heart and lungs do their work, and are supsuccession of images passing through the mind plied with due nerve-power in sleep as well as All that in a moment of time has seemed to prove our in waking. The same with the great organs of "We are alimentation, digestion, and so on. independence of time and space. somewhat more than ourselves in our sleeps, and are concerned with the vegetative life of the orthe slumber of the body seems to be but the ganism discharge their functions during natural Even the muscular organs are more or It is the ligation of sense, sleep. waking of the soul. The muscles but the liberty of reason; and our waking con- less at work: we can sleep sitting in a chair or ceptions do not match the fancies of our sleeps. on horseback, nay even standing. Were my memory as faithful as my reason is may be relaxed, the head may sink upon the then fruitful, I would never study but in my chest, or fall back against the chair, but the dreams."+ In this metaphysical stage of in- body does not fall as it would were muscular Even movements may quiry dreams, not sleep, are the phenomena to power totally abolished. But who shall exhaust the be executed in sleep from reflex action, or mere be investigated. subject of dreams, or who shall review the treat-automatic instinct; but they are not guided by ises written thereupon, and the speculations they have called forth? All have experience of them; all have marvelous stories to relate, and all have But "man is but a theories to correspond. patched fool" if he go about to expound his dreams, and so I do not intend to examine the metaphysics of them. consciousness. In short, we see that, although the body and the bodily functions, muscular and visceral, partake, to a great extent, of the general respite from any thing like hard work, yet they are not stopped, like the higher functions The body does not sleep, the highof the brain. er brain alone does. What are the higher functions of the brain, and do they all and always lie idle in sleep? Here is matter for much curious speculation. The higher functions of the brain we call collectively "mind," and philosophers are now pretty well agreed to divide mind into three Let us approach the positive view of bodily sleep-that sleep, kindly and beneficent, "which covers a man all over, thoughts and all, like a cloak, that is meat for the hungry, drink for the thirsty, heat for the cold, and cold for the hot." This is the sleep which we can really examine positively, as we see it in others, as we see oth-groups of phenomena: 1. Those of intellect or ers enjoy it or fade for want of it, as we see it ideas. 2. Those of feeling. 3. Those of the These are all of them in abeyance in perin the infant who passes more than half its will. whole life asleep, as we see it in the stripling, fect dreamless sleep; but in the different states the sound and dreamless sleep, the dulcis et alta or stages between waking and this perfect sleep quies of healthy vigor, or the sleep of old age, there is every gradation in the activity or inacwhen the inactive brain is either refreshed by tivity of them. If it be asked which of the three short slumbers, or, in its atrophy and second child-groups is most completely extinguished by sleep, hood, sleeps away its declining days. For ex- is least compatible with sleep, we may, I think, cessive proneness to sleep is a sign of decay and at once answer-the will. As sleep steals over us we can neither control our thoughts nor acIt has been noticed in the wane waste of brain. tions. As we fall asleep after dinner the book Cervantes: Don Quixote. Sir T. Browne. † Ibid. or the paper slips from our hands, and we lose | to inactivity, so disconnected one from another, control of thought; we can not fix our attention that nothing like a dream goes on. And this on the page, our ideas wander and get mixed only I conceive to be perfect rest of brain. up or confused, and we slide into oblivion, to In a state short of this perfect rest ideas start dream or not-most likely the former. Here, into train and assume shape and sequence, and then, volition has come to an end, feeling and constitute a dream, and this may become frightsensation will be extinguished, or nearly so; but ful and evoke feeling, and we wake. Further if dreams are going on, the third, or idea-fac- than this I do not wish to discuss dreams: I ulty, will be still active and at work, the others | only mention them to show that, in perfect sleep, being at rest. Sleep, the rest of the brain, is dreams, that is, idea-operations, are absent, as then imperfect: ideas, memories of old events, well as feeling and volition. The mind, or, in of people past and present, long since stored up other words, the highest brain-function, ceases in the brain-granary and in waking-time forgot-to act; nutrition and repair alone go forward ten, now course along one after the other, jumbled in fantastic mêlée, "the fickle pensioners of Morpheus' train." But they do not always excite feeling: we are not always surprised or hurt or grieved or pleased. When they do, when they become more exciting, and we are terrified at the lion or the bull that seems about to seize us, feeling is strongly roused, and we We may conclude from all this, that conwake. The same with external sensations of scious feeling is incompatible with sleep. The cold, heat, noise, or light. Slight sensations course of ideas in a dream may be sometimes we may experience, and still sleep on, but strong preserved in memory, and the feeling they feeling or sensation, and sleep, are incompatible. excite, if very vivid, may by memory be kept The idea-faculty may be at work in sleep almost and reproduced for a long period, but during the throughout; but feeling will be absent, except dream we can not be said to have been conscious in a very slight degree, and volition will be of our real and actual existence. And this quite annihilated; we have no control over our brings us to consider what that is which either dreams. Volition seems to be that perfect har-rouses us from sleep, or forbids sleep to fall upon mony of feeling and intellect which is broken at us, which keeps the brain at work, and hinders once by sleep. in the brain. All animals and all parts of animals require their periodic rest. The heart rests between its beats, the lungs between the respirations, muscles can not always be at work, the stomach can not always be digesting. These are all nourished and revived when not at work, and so is the brain when it rests in sleep. its repose. It appears to be a certain strong excitation of that function of the nerve-centres, which we roughly call Feeling, whether it be the feeling of emotional excitement, such as the passions or sentiments, or fear of impending disaster, or hopes of much-coveted and eagerly ex pain, or even strong sensations of noise or light. All these may be grouped together under the name of feelings, and any one of them, if sufficiently potent, will prevent the access of sleep or banish it from the sleeper. Let us look at this at somewhat greater length. The dislocation of these two, whether by sleep or by any brain disease or disturbance, terminates true volition. But sleep, in which the idea-portion of the mind is at work, is not perfect sleep, or perfect rest of the brain. We wake unrefreshed, and say we have been dream-pected good-fortune, or the feeling of bodily ing all night, and if the dreams have been terrific, and great feeling has been excited, the sleep will have been all the less refreshing. Everyday experience clearly proves that the sounder the sleep and the less the mind is at work during it, the greater is the benefit derived. It is an old and vexed question whether we are Probably the most frequent cause which keeps always dreaming in sleep or not. It was asked awake those who enjoy neither the happy careby Aristotle, and is asked still, and great names lessness of childhood, nor the apathy of old age, may be ranked on either side of the controversy. with its torpid and blunted sensibilities, is menSir Benjamin Brodie and Sir Henry Holland tal worry, or anxiety of some kind or other. say that dreams are always going on: Lord The professional man, whatever his calling, has Brougham thinks the contrary, that we only constantly some important matter on hand, dream just as we wake. It is a point not ca- which may turn out well or ill, about which he pable of demonstration; but we are often awak- can not help thinking. The physician has some ened out of deep sleep without having the slight-patient in danger, who by to-morrow will be est consciousness of dreaming, and if we closely better or worse; the lawyer has some cause célobserve a sleeper, we may often see to some ex-èbre; the artist is thinking whether his picture tent whether he dreams or not. Dreams can not exist in the sleep of a new-born child for the simple reason that ideas do not yet exist. They have not as yet been laid up in the babe's storehouse of experiences: its life is one of sensations and feelings, which when repeated and remembered grow into ideas, but time is required before this can happen. Upon the whole, it is most reasonable to suppose that in perfect sleep we do not dream, that our ideas are so reduced will be hung at the Academy or rejected; the speculator is wondering whether the funds will rise or fall; each one's bread and his family's, his fame and fortune, is at stake; he is overanxious, he can not sleep. Another has been sitting up late at some brain-work, and though, perhaps, he has no great fears about it, yet he has been working long and hard, and he can not forget it and shake it off, and it follows him after he has laid his head on his pillow, longing for sleep. Anticipated pleasure, no less than | er it be pain, or the fright of a dream, or an external sensation, it excites the centre beyond sleeping point, and we wake. fear, may excite and rouse us and banish sleep. The eve of many a day of keen enjoyment to be marked with a white stone, the first of September, or the long-looked-for holidays, have brought but scanty slumbers to expecting youth. As men grow older they take such things more quietly. The giorni da festa are rarer and less gay. They are kept awake more by anticipated pains than pleasures. toe. Not only mental but bodily causes also may prevent sleep. There may be discomfort of every conceivable kind, from actual violent pain to the malaise of dyspepsia after an indigestible meal, or an uncomfortable position, or an illmade bed. Most of us have been kept awake by pain of some kind, a raging tooth or a gouty And most of us know the uneasiness attending upon indigestion, which, though it may not amount to pain, does nevertheless, by that mysterious process which the old writers called "sympathy," react upon the nervous centres, and stimulates them sufficiently to banish sleep. And in the same way hunger, when there is nothing at all to be digested, will often keep us awake. Cold will prevent sleep; so also will undue heat. Here, too, is discomfort, and besides this, cold extremities bear a certain reference to the general circulation of the blood, which also is affected by excess of heat. Any stimulus of the external senses will prevent sleep, and any thing to which the senses are not accustomed will stimulate them. We most of us need the silence and the darkness of the night to lull us, but fatigue and custom will overcome this habit, and many can in a short time sleep in daylight, or with incessant noise sounding in their ears. And the very withdrawal of this accustomed noise will often act as a stimulus to these persons and rouse them up. What is the explanation of all this? Why are we prevented from sleeping: why are we aroused? What is the physical condition which favors or repels sleep? This much we may conclude from what has been already said, that, as sleep is the rest of the highest part of the brain, it must be a condition of this part which favors or repels sleep. Healthy sleep presupposes a healthy state of brain, and we must carefully exclude from our notions of sleep all those phenomena which are the result not of healthy but of unhealthy processes going on in the brain, some of which, though apparently akin to sleep, nevertheless depend on an entirely opposite condition of things. Such states as coma, trance, catalepsy, insensibility from apoplexy or pressure, or alcohol or poisons, have only this in common with sleep, that there is unconsciousness: they differ altogether in the fact that from this unconsciousness the sufferer can not be roused. From healthy sleep we can be roused easily. Recent observations and researches seem to prove to demonstration that the sleep of man and animals depends on the state of the circulation of the blood in the brain proper. One theory, which I mention, but which is now nearly abandoned, is that it depends on the pressure of distended veins. The modern opinion, and I believe the true explanation, is, that it follows a diminution both in the quantity and rapidity of the circulating blood, and that if this reduced rate of circulation be increased by any cause sleep departs. The writings and experiments of Mr. Durham, Dr. Jackson, and others have thrown great light on this subject, and tend strongly to remove all doubt as to this being the true interpretation. As it is clearly of great practical importance that we should know what it is that we want to bring about when we are try What wakes us up when we are sleeping a healthy sleep? Very little will do it, when we have had a good long refreshing sleep, comparing to procure sleep, it will be well to examine atively slight external stimuli-sound, light, or the theory briefly. The principal evidence as to touch. We are said to wake of our own accord, the state of the human brain in sleep is derived which means generally that some little incident from the observation of a woman at Montpellier, rouses us from our light morning sleep. It is a case well known and often quoted. She had in the morning, too, that we dream most, which lost a portion of the skull-cap, and the brain and goes to show that we dream in our light, and its membranes were exposed. "When she was not in our profound sleep. But if we have only in deep or sound sleep, the brain lay in the skull been asleep a short time, it takes a loud noise almost motionless; when she was dreaming it and a hard push to wake us. But we may be became elevated, and when her dreams, which roused by other causes besides external ones: she related on waking, were vivid or interestwe may be disturbed by bodily pain, or internal ing, the brain was protruded through the cranial discomfort, or by an uneasy posture. Lastly, aperture." This condition has also been experwe are often waked by a vivid dream. The imentally brought about and observed in anifeeling of the nerve-centres is strongly stimula-mals, and the same result has been seen, nameted by something or other, and the result is ac- ly, that in sleep the surface of the brain and its tion, as it is after every excitation of feeling, membranes became pale, the veins ceased to be action either mental or bodily. A certain distended, and only a few small vessels containamount of action may take place without wak- ing arterial blood were discernible. When the ing: we change our position in sleep if it be un-animal was roused, a blush spread over the brain, comfortable, and then we probably sleep on. Nay, we may even be prompted to the action of the somnambulist, or somniloquist, without waking; but if the stimulation be strong, wheth which rose through the opening of the bone. The surface became bright red; innumerable vessels, unseen before, were now every where discernible, and the blood seemed to be coursing through them very rapidly. The veins, like the arteries, were full and distended, but their difference of color rendered them clearly distinguishable. When the animal was fed and again allowed to sink into repose the blood-vessels gradually resumed their former dimensions and appearance, and the surface of the brain became pale as before. The contrast between the appearances of the brain during its period of functional activity, and during its state of repose or sleep, was most remarkable.* These observations entirely contradict the theory that sleep is due to pressure from distended veins, to venous congestion. And further experiments made by Mr. Durham proved that when pressure was made upon the veins, and distension of them produced, the symptoms which followed were not those of sleep, but of torpor, coma, or convulsions. And this view is completely corroborated by what we know of diseases which are accompanied by these symptoms. Common observation, too, confirms it; we must often have noticed when looking at a person asleep, that the face appeared paler than usual, and that a flush came over it on waking; and all are agreed that the general circulation is diminished, as also the respiration, during sleep. A person in tranquil and natural sleep often breathes so slowly and so gently that we are obliged to listen attentively to discover that he breathes at all. Can we go any further? Can we say why it is that the diminished supply of blood produces sleep and rest for the brain? We may have recourse to one of two theories, but here we can not bring demonstrative proof so easily as we did before. First, we may propound a chemical theory, that oxydation of the brain-substance, being in proportion to the vascular activity, is diminished as the latter is reduced, and then sleep follows. This is true, no doubt, so far as it goes. That the blood in the brain changes from arterial to venous, parting with its oxygen, we know, but there still remains the question, why does the arterial action lessen so as to allow of sleep ensuing? The chemists say that the products of oxydation accumulate, and by their accumulation interfere with the continuance of the process, and act as a kind of regulator, just as a lighted taper is extinguished in a close jar by the products of its own combustion. But we constantly see that this is not the case, that although the brain action be violent in the extreme, and sleep be absent for days together, no products of oxydation put a stop to the process, but it goes on till ended by death. Chemistry fails, as it always does, to explain the whole of any vital process. In the more guarded, though less mathematical, language of physiology, we may say that every thing which stimulates the brain to a certain amount of action prevents sleep, and that this stimulus must be removed before sleep can be obtained. The stimulus may arise within or without the bodily Durham on the "Physiology of Sleep."-Guy's Hospital Reports. 1800. organism. External events influencing the mind, and causing cares and anxieties-hopes and fears; or affecting the body, as heat and cold-may quicken the circulation and drive away sleep. The stimulus, too, may arise from within. The disordered stomach may, by sympathy with heart and lungs, quicken the flow of blood to the brain, and either banish sleep or disturb it, and so bring to us all the horrors of nightmare. That mental emotion does quicken the brain circulation is a fact known to all; whether it be slight or whether it be violent, transitory or permanent, it increases cerebral action. And this acceleration once established does not cease of a sudden. An instant conversion of fear or anxiety into the certainty of prosperity or success may sometimes at once bring relief, and from sheer fatigue sleep may follow, but more frequently the effect of the mental tension is kept up for some considerable time. When we have been working for hours with toiling brain we do not go to sleep the moment we lay our heads on the pillow-sleep comes to us slowly and coyly. The head feels hot, and we hear the rapid pulse beating in it as we lie, and only by degrees does the quickness of this abate. Why brain-work raises the rate of the circulation, is a question of physiology which, like many others, we can only answer by having recourse to general principles. Whenever any part of the body is actively employed a larger supply of blood is sent to it: as motion warms our hands and feet, so the working brain demands and procures a larger supply of blood than the idle one. And the brain is stimulated beyond all doubt, not only according to the quantity of the blood sent to it, but also according to the nature and quality of it. It is reasonable to suppose that alteration in this must affect the brain-function, and observation and experiments prove that it does. From all this that has been said about the various circumstances which prevent sleep it may be possible to deduce the methods of procuring it, at any rate, on some of the occasions when it appears as if it would never come. Many persons are habitually bad sleepers, and all know what it is to lie awake and be unable to go to sleep, even when they are in ordinary health. We can promote sleep by removing every thing which is likely to stimulate the brain and the brain circulation, and also by reducing the circulation by other means, and lessening the susceptibility and excitability of the brain as far as possible. First, we must get rid, so far as we are able, of all sources of discomfort which are likely to harass and stimulate the brain. Mental anxiety and worry are perhaps the most frequent of these. But it will be said that we can not remove anxiety. This is too frequently true; and then, if it banishes sleep night after night, and the sufferer is harassed and worried and gets no rest, serious results follow. If the anxiety or grief be irremovable, something ought to the one goes to sleep, the other lies awake half be done to counteract it, and to substitute other thoughts in the place of it. Change of locality, change of companions, will often break through the dominant and painful idea, and repose and quiet will soon follow. Possibly it may be not over-anxiety, but simply over-work that for nights together prevents us sleeping, and this is more easily dealt with. The late and excessive work must cease. If we have been toiling till midnight, and then with heads full of our subject go to bed to lie down and take no rest, we must give it up or take the consequences. It will not do to lie awake, day after day, till three or four o'clock in the morning. We can not counteract this state of things; the brain is over-worked and over-stimulated, and the stimulus which keeps up the active functional circulation must be removed. Again, if sleep be prevented by bodily discomfort, external or internal, this must be remedied so far as it can. The bed may be too hard, or too soft, or too short; the pillow may be too high or too low. Heat and cold will much affect the circulation in the head. If the surface and extremities are cold, especially the feet, there will be a deficiency of blood in them, and consequently an excess in the internal parts, and in the head. In this way we are kept awake by cold as much as by the actual discomfort arising from it. Heat will directly accelerate the circulation.ger and more difficult the digestion, the more And although the fatigue caused by heat may in some degree counteract this, yet most people sleep less in the very hot nights of summer than they do in cooler weather. We are both prevented from going to sleep, and roused from sleep, by this cause. Excess of heat and cold are to be avoided if we wish to sleep soundly. Bedrooms must be warmed in winter and cooled in summer; people must get over the old prejudice about opening bedroom windows, and must eschew feather-beds and mountains of blankets. Many a one, if he do this, will sleep better than he has done all his previous life. Another thing which promotes sleep is the partaking of food. As indigestible food hinders sleep or rouses us from it, so a digestible meal favors it. All know what it is to feel sleepy after a hearty dinner, nay, even a light lunch will often have the same effect if we sit or remain inactiye after it. And this is not due to the strong liquids imbibed, for a dinner with water alone may have the same effect. There are different theories as to the cause of our being rendered sleepy by food. One is, that the circulation is affected by the ingestion and digestion of it: that an extra supply of blood is directed to the stomach and digesting organs, and so diverted from the head. The circulation in the head is lessened, and sleep ensues. This idea is probably not incorrect, and partially explains the phenomena, but not entirely. It seems insufficient to account for the sleepiness produced by some kinds of food, and the wakefulness caused by others. One man, at ten o'clock at night, takes a glass of beer, another an equal quantity of green tea It can be col A blood would be diverted, and the sounder the sleep. But, on the contrary, we know that the more indigestible the food the more sleep is prevented, while quickly-digested materials, which are easily assimilated, promote slumber. single small cup of tea can hardly be said to require digestion; yet this will banish sleep from many, and can only do so by affecting the nerv ous centres. If there is undue excitability of the brain, and the ordinary stimuli of thought or noise are sufficient to keep off sleep, if the nervous susceptibility of the individual of itself keeps him awake, what can be done in addition to the means already mentioned? We must try and lessen this excitability, from which some occasionally suffer till it almost constitutes a disease. This may be done, and often is done, by non-medical methods. In fact, we know that each one has his proper and peculiar recipe for going to sleep. One man counts tens, hundreds, or thousandscounts till he can count no longer. Another repeats from memory Latin verses, it may be, or English poetry. One man fixes his attention strongly on one subject, and tries to exhaust himself upon this. Another does just the oppo site, and tries to think of no one thing, but to jumble his ideas into a confused chaos as he finds them wandering when he is dropping off to sleep; and this man probably succeeds the best. Now these plans for the most part are based upon the principle of diminishing the excitability of the brain by means of fatigue. We know that in health fatigue is one of the chief causes of sleep. Fatigue of body and fatigue of head, not calling up anxiety or emotional |