We are all acquainted with the tale of the man who was blind in one eye and deaf in one ear, who at once went to sleep when his sound eye and ear were closed. In this case there was nothing to stimulate the centers of perception in the brain.
This example is very instructive for the question we shall now have to discuss. The best hygiene of sleep is to avoid all agencies that may cause excitation of the brain. We have seen, in the preceding chapter, that an anæmic condition of the brain must be sought; and this is best attained when the brain is at complete rest and nothing is acting on it which may cause an afflux of blood, and thus hinder an anæmic condition. A sleeping brain must not work, as any kind of mental labor, even the smallest noise, when it is able to attract attention by having been conveyed to the centers of perception, may impede sleep. Sometimes the loudest noise, such as an electric car passing with bell ringing, will not awaken us, or prevent our falling asleep, if we are accustomed to it; for it will then excite no attention and consequently will cause no work for the brain; but should some one speak loudly in an adjoining room, or should any unusual noise occur in our vicinity, although infinitely less than the above mentioned, it may be sufficient to prevent our sleeping, for we pay more attention to it, and thus the repose of the brain is prevented.
The miller will sleep soundly in spite of the rumbling of his mill wheels, to which he has been accustomed for years; but should the mill stop he may awake, for this would arrest his attention.
From the foregoing it follows logically that in order to sleep soundly it is best to exclude everything that can arouse the organs of perception, and which, if conveyed to the brain, may invite attention and thereby brain work. We must, therefore, exclude noise and light from our sleeping chamber, as we all know from personal observation that we sleep soundest in a room that is thoroughly darkened and where no noise can penetrate.
Some people are accustomed to a slight light in the room during the night, for complete darkness would create attention, and thus they would not be able to sleep so well. For such the light through the transom will be advantageous; but for many people such light would prevent them falling asleep.
When a sleeping chamber is too warm we may be prevented from sleeping; people mostly sleep best in a room that is not warmed, as this favors an anæmic condition of the brain and excludes the sensation of heat that is adverse to sleep. We also sleep better in autumn and winter than in summer, unless the room be heated and an artificial summer created thereby.
The air in the room must not be oppressive, so as not to invite the attention of our senses of perception; it would, therefore, be wisest to take the largest room in the house to sleep in, and not the smallest, as many do. People with a large bedroom and small sitting-room will have more chances for a long life than those reversing this order of things. A hygienic bedroom must be large, not heated during the night, and the upper part at least of the window should always be open, and preferably one at a part of the house facing a large garden or open space.
In order that the brain may be at rest it is essential that the other organs should also be resting. Any organ that is working, particularly if the work be laborious, or if the organ be diseased, will send impulses to the brain. It is very difficult to sleep if any part of the body is aching; the sensory nerves bring this to the center of perception in the brain, and this awakens us. When the stomach is loaded we may the sooner drop to sleep, for reasons mentioned in the preceding chapter; but digestion during sleep is more labored, and thus again impulses will be sent to the brain. The same occurs when the intestines are filled with gases.
This necessitates the practical advice not to eat too much for supper, and particularly not to go to bed for some two and a half to three hours at least after that meal; and most people will sleep better if they do not take much meat, and for such as suffer from sleeplessness not any meat at all, at night. The most hygienic hour for our evening meal would be about 7 o’clock, not later; and for the prevention of sleeplessness 6 o’clock is better.
But if it is difficult to sleep with the stomach full, an empty stomach may also cause difficulties, particularly when there is much hydrochloric acid in the stomach. A glass of milk and a biscuit is a good remedy if awakened from such causes.
Flatulency also may often be the cause of disturbed sleep, and to prevent this certain kinds of food, liable to cause it, should not be taken in the evening; such are beans, peas, or lentils, and potatoes especially, if beer be taken at the same time. By such combinations a regular chemical laboratory in the intestines will be formed during the night, and for five to six hours after such a meal, or longer, according to the time we go to bed, sleep will be disturbed. So long as there is flatulency it is impossible to sleep, and the quickest way to put an end to it is to insert a suppository of glycerine into the rectum, which will soon cause a copious evacuation, provided that the intestines have not been previously weakened by too many drugs. After this remedy the flatulency will cease, and sound sleep for the rest of the night will follow.
Many people are apt to awake during the night after five or six hours’ sleep if they have partaken of much meat at the evening meal and then gone at once to bed. Only to catch an early morning train would it be permissible to commit such a breach of the true hygiene of sleep. To observe this hygiene fully we must also avoid taking mineral waters with diuretic action for some time before going to bed, for the dilatation of the bladder from the accumulated urine may convey sensations to the brain and thus disturb sleep.
Total sexual abstinence may cause insomnia, especially in persons who do not observe complete chastity; for this marriage is the best preventive, as it is for other troubles of a like nature.
In women, when menstruation comes on, there is also disturbed sleep very frequently; and many unmarried women suffer from insomnia.
Sleep can the more easily be disturbed when it is the lightest, which is generally the case during the early morning, for which reason at this period all noise should be most carefully avoided. Sleep about midnight is generally the deepest, and a noise that would not disturb us at that hour will frequently do so in the early morning hours; thus, the midnight hours being the best for sleep, it seems advisable to go to bed about ten or half-past ten, and it is certainly not hygienic to retire after twelve, as then it is more difficult for most people to get asleep than it is at ten or eleven.
It follows from the preceding considerations that mental work in the hours before going to bed will be contrary to the hygiene of sleep. When the brain is engaged in intense thought there is an afflux of blood thereto, as mentioned before. It takes some time before the brain becomes sufficiently anæmic for sleep; for which reason also it is not wise to read books, especially interesting ones, in bed. It is a very bad habit to read in bed until late in the night, as is done by many ladies who complain of insomnia and take somnifacient drugs instead of extinguishing the light as soon as they go to bed, and excluding all agencies that may excite their attention, in order to allow the brain to come to a state of rest.
We must now answer the question: How many hours’ sleep shall we indulge in?
On an average, for the adult male, six to seven hours’ sleep is necessary to feel rested thereafter and to fully appreciate the saying that “Sleep is Nature’s sweet restorer.” Young girls and women require much more sleep than do men; but children, and especially infants, require the most.
Infants are usually almost always asleep, possibly owing to the fact that the thyroid and other ductless glands are not yet fully active; and for this reason children also require longer sleep. The older we get the less sleep we require. Sometimes in old age there is obstinate insomnia, which is due to changes in the blood-vessels of the brain, by which high blood-pressure is caused and the anæmic condition of sleep prevented.
It is unwise to say you must sleep six, seven, or eight hours to have enough. Each individual requires a different time according to his bodily requirements, which he must study by careful observation. The deeper the sleep, the shorter will be the time that will be required for it. The essential thing is to feel rested in the morning, and it does not matter if we have slept only five and one-half hours if we only feel that we have slept enough. There are many people, usually over 50 years of age, who feel rested and perfectly well after but five hours’ sleep. But if after even seven hours’ sleep we still have a feeling of weariness and depression, so to speak, we have not freed the body of toxic products during sleep, so the time was insufficient and must be made up the following night.
It is a very strange thing, when we have not been able to sleep long enough for one or two nights, and we do not feel in good condition in consequence, that a longer sleep on the third night will be able to restore us entirely. I believe this is a clinical argument in favor of the theory that sleep serves to free the body from the products of intoxication, which may be stored up for two or three days and disappear after one night’s sufficient sleep.
Too much sleep may be nearly as bad as too little. After sleep too long continued we feel very heavy and oppressed; we must, therefore, observe the right medium in this as in everything else. The greatest maxim for longevity is moderation in all things.
Granted the great importance of sleep as a function of ridding the body of toxic products and of replacing spent energy, it will be only too natural for us to do our best to assure its regular performance if we are desirous of living long and retaining the vigor of youth as much as possible. Indeed, sleeplessness, if continued for a few nights, is most dangerous in tending to produce premature old age. We have only to look at the face of a person who has passed a sleepless night or nights and we shall see sunken eyes, hollow cheeks, and pendant features which bear a strong resemblance to the face of an elderly person. It is then interesting to note how one night of sound sleep will restore the normal youthful appearance, which is an indication of the beneficial influence of sleep in the problem of senility.
Sleepless nights must be avoided by every means. If possible never travel at night, unless we feel assured that our sleep on the train will not be disturbed; always, if we can, give the preference to day travel. The less often we go to bed after midnight the better will be our chances for the retention of youth and a long life.
Going to bed early enables us to rise early; and this is a powerful factor in long life, proven by the fact that the majority of people living to be 100 or over were early risers. The great importance of this has been perpetuated by Franklin, the founder of many notable societies and institutions, in the familiar verse:—
Franklin lived to be 85 years old.
We have often noticed very old people go to bed after sunset and rise with the earliest dawn. As a rule, people who go to bed early, some hours before midnight, enjoy the soundest sleep because of the fact that sleep is always deepest at about midnight. Usually only those living in villages can indulge in this healthy habit, and doubtless this is one of the reasons for their long life and robust health.