CHAPTER XVIII THE HYGIENE OF THE NERVOUS SYSTEM. (Part 1)

CHAPTER XVIII THE HYGIENE OF THE NERVOUS SYSTEM. REST AND SLEEP In no respect do the conditions of modern life stand in more striking contrast to the life of former times than in the increasing importance of mental work in contrast with muscular work as a means of support. Not only are there more professional men, — such as lawyers, editors, physi- cians, teachers, and the like, — but the character of modern business life involves no less the use of the nervous system both on the part of those who direct large enterprises and | of those who occupy subordinate positions. The clerk in a bank, as well as the president or cashier, is “living by his wits” and is using his brain to an extent rarely seen until within the last century. Never was competition so keen; never has it been so necessary to inform oneself minutely as to market conditions of demand and supply; never before has the margin of profits been so small; never before has it been so necessary to avoid waste; and never before has it been so difficult to protect oneself against novel and unforeseen conditions. Truly the modern busi- ness man must-be ever awake, ever alert. Nor is this all. With the introduction of the telegraph and telephone, communication between man and man is facilitated ; the widespread employment of stenographers — results in an increase of letters received and sent; and in other ways the number of, matters demanding atten- tion is multiplied many-fold. Moreover, the increase of wealth has enlarged the possibilities of life ; concerts, art 304. ory Pega ee rear ry HYGIENE OF THE NERVOUS SYSTEM 335 exhibitions, books, crowd upon us; social engagements are multiplied; so that as a result we are kept ever on the alert, and the man or woman who does not firmly decline invitations, engagements, and efforts which would overcrowd life to no good purpose, experiences elements of distraction, or fatigue, or worry, which tell upon health and too often lead to what we call nervous pros- tration. For no student of the practical problems of hygiene _ean shut his eyes to the marked prevalence of nervous prostration and even insanity, or fail to recognize the evident connection between these things and the intensity, the hurry, the unrestful character of the lives we lead. Probably there is no more pressing problem of practical hygiene than that which is here presented. And even where there is no question of nervous prostra- tion or insanity, a large number of people suffer from nervous troubles of one kind or another which interfere seriously with their work and with the legitimate enjoy- ment of life. We have seen how close is the connection between all parts of the nervous system, and also how condi- tions of the nervous system may and must influence nutri- tive and other functions of the body. The two are most intimately bound together, and many a man or woman fails to secure the blessing of good health because in- tense, unremitting work is demanded of the nervous sys- tem, suck’ as would never be imposed on the muscles, or the stomach, or the skin. Consequently the avoidance of actual nervous prostration is but a small part of what must be accomplished by the hygienic conduct of life; a far more pressing practical problem is the lessening of daily strain, worry, and fatigue which are the precursors of the more serious troubles, and the avoidance of which affords the only sure means of defense against the all too common and distressing breakdowns of useful lives. 296 THE HUMAN MECHANISM Christian nations have always had in Sunday one day in seven when most of the work of life may be suspended and the strain relieved; and the preservation as far as possible of Sunday as a day of rest is a matter of sound hygienic policy. Recent years have also shown encour- aging signs of relief from steady strain in shorter hours of labor, in the early closing of shops on Saturday, and in the more general use of vacations in summer. These are all to be welcomed and encouraged, but a large amount of strain still remains; the value of the Sunday rest is largely nullified when we go back on Monday morning to an intense appli- cation which continues without break until Saturday night. 1. What causes Nervous Strain ? — The nervous system, in common with all other ‘organs of the body, is unfavor- ably affected by unwholesome conditions or acts of life. Improper feeding, sedentary occupations, bad ventilation, or overheating of houses tell upon its working capacity ; and the effects of such conditions upon the nervous sys- tem are often wrongly attributed to mental work or over- work. Especially is this true in the matter of muscular activity. Many break down with nervous prostration, not because the brain and spinal cord have been overworked, but because, in an excessive devotion to business, or sci- ence, or literature, or art, or pleasure, or even because of sheer idleness, the muscular system has been neglected and has accordingly failed to minister to the rest of the body. At the same time it often happens that despite proper mus- cular activity, proper feeding, etc., the element of strain is still present. Muscular activity itself entails extensive nervous work, and the nervous activity which participates in muscular work may be only a part of the sum total which produces overstrain, and even leads at times to nervous prostration itself. 2. Misdirected Nervous Activity. — It is very important to understand clearly that it is misdirected nervous activity, ‘= ; z - a i = “=~ > ¥ = 5 Mis ia ey we’ rt eee HYGIENE OF THE NERVOUS SYSTEM 3837 and not mental work in itself, or the concentration of attention which mental work requires, that leads to bad results. It is a part of our normal life to do mental work and to cultivate the power of close application to that work ; it is a part of education to develop the power of concentra- tion and attention against resistance and inclination, and experience shows that this may be entirely consistent with the maintenance of health. But when a student “ crams ”’ for an examination for two or three days, with the minimum of sleep during the period, and breaks down after it is over, it is not merely mental work which should be blamed for the result; for he would probably have broken down if he had attempted to work a typewriter during the same time, with no more relaxation or rest. The real cause of the trouble is the too long continued use of the nervous system. 3. Mental Work and Overwork.— Much nonsense is said and written about “working the brain too hard.” If by this is meant working it too long at a time without rest, or without stopping for muscular exercise ; if it means the attempt to do more sums in arithmetic, to read more Latin or German, to write a longer composition, or to master more science than the hours of study justify, and so pro- long these hours of study to the neglect of other hygienic demands, no objection can be made to the phrase; but if it refers to the hard mental work and close application required for a reasonable time by a sum in mathematics or a passage in Latin, we may well hesitate to regard such work as in any degree dangerous. The world is overflow- ing with people who have never acquired habits of mental concentration and hard thinking; and yet their general health is no better than that of persons who have acquired such habits, while their mental powers often suffer severely by comparison. In the physiological portion of this work the anatom- ical and physiological aspects of the nervous system were 338 THE HUMAN MECHANISM carefully described. One of the chief reasons for doing this was to impress upon the student the extreme complexity of the mechanism, the great number of parts (neurones) which are concerned in our actions, and the natural diffi- culty, as well as the necessity, of proper coordination. In the work of a muscle it is not so important if some of the fibers fail to do their work, provided the remaining fibers work harder, and so exert the same pull on the tendon, for the work will still be done. But it is not so with the nervous system; if ten or twenty neurones of a given nervous mechanism fail to work, the work will not be — done at all, or will at best be done imperfectly. In any mechanism of interdependent parts, weakness of one part means weakness of the whole. The secret of efficiency in the nervous system as a whole is the maintenance of the efficiency of each and every unit. 4, The Care-ofthe Nervous Machinery. Rest and Sleep. —If a locomotive is to be kept in the state of high effi- ciency, it must not be worked without ceasing until some- thing goes wrong. When a train is to be pulled three hundred miles it is customary to change engines two or three times on the run; and these changes are made, not because the first engine cannot pull the train to its desti- nation on schedule time, but because heating occurs, or dust finds its way into the bearings, or the strains and jars impair adjustment; and it prolongs the life of the machine and its good working to remove the dust, cool the parts, and otherwise frequently put the engine in perfect order. When an engine breaks down, it is usually because some one part has given way. With proper care a good machine should wear out but not break down. The central nervous system, although infinitely more complicated than the steam locomotive, is far less durable as a mechanism. Its bearings are not made of hard steel, but of living, irritable protoplasm keenly susceptible to ‘ ¥ — ~ HYGIENE OF THE NERVOUS SYSTEM 339 fatigue. In the numerous connections between neurone and neurone there is the same chance as in the steam engine that some one part will fail to do its work; and the main principle of its hygienic care is to oil the bearings and clean and repair the machinery, by repose and sleep, before the danger of a breakdown is imminent. Rest, and especially the rest of sleep, is the one preventive for these unfavor- able conditions; by these alone is the fatigued neurone withdrawn from work and given the chance to repair itself and to return to its normal condition. 5. How Much Sleep is Advisable? — Different people undoubtedly require different amounts of sleep ; but it is safe to say that the vast majority of adults require from seven to eight hours a day; children and young people require more. It is, however, an interesting question whether all of this should be taken at one time or not. Since the nervous life of to-day is more intense than was that of our ancestors, it is all the more needful that we keep the nervous system in a continuous state of high efficiency. To go about the duties and pleasures of life from early morning until late at night without a moment’s rest is a great mistake; we are then doing what the engineer would do who should run his engine all day, feeding it with coal but without giving it a drop of oil, without tightening a nut, without cleaning a bearing. As the play of nervous activity goes on, now calling upon one combination of nerve cells, now upon another combination, those nerve cells which belong to more than one mechan- ism are called on for more than their share of work, and every mechanism to which they belong may be to that extent impaired. The stimulus of the will must be more vigorously applied, and as this becomes ineffective, the individual is tempted to use stimulants, as the whip is applied to tired and straining horses, or as blows were showered upon galley slaves in time of battle. 340 THE HUMAN MECHANISM Contrast with this the benefit of brief sleep during the day in facilitating night work. Some persons, it is true, do not seem to be thus benefited, but the vast majority are. And the benefit is out of all proportion to the time spent asleep. We are tired and work is difficult, not so much because the whole nervous system is exhausted, but because unfavorable conditions of fatigue, etc., have come in at important points; during even a short nap, with its marked muscular and nervous relaxation, normal condi- tions are restored and the whole mechanism then works on with less effort, less general fatigue, less local injury. 6. Nervous Rest in Change of Work. — Sleep is the very best means of insuring local nervous repair, because it is the only condition which involves complete relaxation. There is, however, some rest, or at least some refreshment, in mere change of employment; as when, for instance, we pass from mental work to physical exercise. Calling into play a new group of nerve cells gives a chance for rest to many cells which have previously been active. And at times we feel tired after mental work because we need muscular activity rather than sleep. The tired feel- ing may come not from tired nerve cells but from the want of what the muscles might furnish (see Chapter XVII). At such times muscular exercise to some extent, perhaps to a great extent, refreshes us; and in general we maintain a higher degree of working power by judicious variety of activity. But it must be remembered that, in the long run, neither muscular exercise nor any other change of occupation can take the place of the complete relaxation and refreshment found in sleep. It is, indeed, doubtful whether there is any change of employment which brings with it an entire change of nervous activity. A certain number of the same cells, already weary, are still kept at work, as has already been explained above; and it is by sleep alone that every cell has its natural opportunity J anodic diabetes bea gt LY » p Ue ee Se eo edals HYGIENE OF THE NERVOUS SYSTEM — 34] for repair. Those who would define rest as “selected excitement” should bear this fact carefully in mind. The cardinal principle in the care of the nervous system is thus the same as that in the care of the steam engine. Do not often call upon it for activity of any kind when conditions of undue fatigue are likely to be present. Go to the performance of every physiological activity, to diges- tion, to study, to muscular work, to social life, —for all these mean nervous activity, —as far as may be with a rested nervous system. Of course to do this is not always possible ; there are times when we must drive the body to mental work despite the fact that it is physically tired ; but this ought to be the exception, never the regular order of life. 7. Examples. — Let us suppose that some one, man or woman, after application at sedentary work for six or eight hours, has some time free before the evening meal, and that, tired and perhaps nervous, relaxation is sought in a brisk walk, which is almost immediately followed by dinner. The effort which the digestion of this, perhaps the heaviest meal of the day, costs the nervous system shows itself in a stupid, almost somnolent condition which often follows. The body is trying to do hard work with a tired nervous system, some of whose bearings need oiling ; its owner is making the mistake of continued activity without opportunity for the rest and repair which a nap of fifteen or twenty minutes, or even absolute idleness and complete muscular relaxation without sleep, for half an hour or so before the meal, might have given him. Again, there are times in every one’s life when some unusual strain must be borne; when, for example, after the day’s work watch must be kept at a sick bed during the greater part of the night. Too often people will undertake this strain, expecting to “make up” the loss of rest when it is over, even when it is possible to prepare 342 ‘THE HUMAN MECHANISM for it by an hour or so of sleep beforehand. We seldom work steam engines in this way. Should we treat the nervous system less carefully than a steam engine? These examples must suffice. The application must be made by each individual according to his work in life. If work is undertaken which requires constant activity from early morn until late at night, the case is hopeless, and the only remedy is a change of occupation. Only gross ignorance of the plainest facts of human experience, as well as of physiological science, can excuse such conduct. 8. Muscular Relaxation in Sleep.—Sleep and rest involve muscular relaxation. All have noticed, when falling off to sleep, the feeling of relief from strain; the framework of the skeleton seems to be held together less rigidly, and finally, as we lose consciousness, relaxation seems com- plete. And at times when sleep will not come, many have felt the inability to relax ; when, as it has been well expressed, we seem to be afraid that the bed will slip away from under us and we must hold on to it. We have seen that during waking life the nervous system is con- tinually sending out impulses which keep the muscles in a state of moderate contraction, and thus among other things liberate heat for the maintenance of the body temperature. Usually this tonic activity of the motor neurones must