SLEEP
IT is hardly a “burning question”; it is not even a “problem that presses for solution.” Nevertheless, to minds not incurious as to the future it has a mild, pleasing interest, like that of the faintly heard beating of the bells of distant cows that will come in and demand attention later.
It by no means appears that sleep is a natural function, the necessity of which inheres in animal life and the constitution of things; there is reason to regard it as a phenomenon due rather to stress of circumstances—a kind of intermittent disorder incurred by exposure to conditions that are being slowly but surely removed. Precisely as sanitary and medical science and improved methods of living are gradually extending the length of human life in every civilized country and threatening the king of shadows himself with death ere, in the poet’s sense, “Time shall throw a dart” at him, so we may observe already the initial stages of a successful campaign against his brother “Sleep.” Civilized peoples sleepfewer hours than savage ones, and, among the civilized, dwellers in cities fewer than country folk. The reason is not far to seek: it is a matter of light.
Primitive Man, like the savage of to-day, had at night no other light than that of the moon and that of wood fires. For countless ages our ancestors lived without candles, and when they had learned the trick of burning rushes soaked in the fat of neighboring tribesmen their state was not greatly better. Beyond Primitive Man we may dimly discernhisancestors—unmentionable to ears un-Darwinized—who had no artificial light at all. In the darkness of the night and the forest what could these ancient worthies do? They had little enough to do at any time, but even their rudest pursuit—that of one another—could not be carried on in darkness. They did nothing, naturally assuming the most comfortable posture in which to do it, the earlier sort suspending themselves by their tails, the later, having no tails, lying down as we do to-day, or rather to-night. It is a law of nature that when the body, or any organ of it, is inactive a kind of torpor ensues; the blood circulates in it with a more feeble flow; molecular changes take place with a lessenedenergy—in short, the creature begins to die, and can be restored to full life only by renewal of bodily activity. In the instance of the brain this torpor means unconsciousness—that is to say, sleep. To put the matter briefly, darkness compels inaction, inaction begets sleep.
Another law of nature—a rather comical one—is that acts which we do regularly, from choice or necessity, set up a tendency in us to do them involuntarily when we don’t care to; and when the original impulse has been replaced by this new and more imperative one we give it the name of habit and flatter ourselves that we have explained it. Because our pithecanthropoid and autocthonic forefathers, unable by reason of darkness to indulge during the whole twenty-four hours in the one-sided pleasures of the chase and the mutual joy of braining one another, had to sleep,wehave to sleep; although we have (by paying sorely for it) plenty of light for many kinds of malign activity.
But little by little we are overcoming the sleep habit without loss of health, if not with positive sanitary advantage. As before pointed out, the people of our lighted cities sleep less than the rural population; and thissleeps less than it did before the improvement in lamps. Nothing is more certain, despite popular opinion to the contrary, than that the men of cities are superior in strength and endurance to those of the country, as is abundantly attested in army life, in camp and field. That this is wholly or even greatly due to their nocturnal activity is not affirmed; only that their addiction to the joys of insomnia has not appreciably counteracted the sanitary advantages of city life—amongst which an honorable prominence should be given to defective drainage and drinking-water that is largely solution of dog and hydrate of husband from the city reservoir.
The electric light has apparently “come to stay,” but more likely it will in good time be replaced by something that as far exceeds it as itself beats the hallowed tallow candle of our grandmothers. Not only will the streets and shops and dwellings of our cities be illuminated all night with a splendor of which we can have hardly a conception, but the country districts as well; for it is now known that plants (which apparently are not creatures of habit) do not need sleep, and that by continuous light the profits of agriculture could be enormously increased. The farmerswill no longer retire with the lark, but will work night shifts, as is already done in factories and mines, and eventually work all the time, in order to support the rest of us in the style to which we have been accustomed.
On the whole, I think it not unreasonable to look forward with pleasant anticipation to a time, some millions of years hence, when the literature of sleep will be no longer intelligible, and the people of even this country be sufficiently wide awake to prevent the tenper centumof their number devoted to patriotic pursuits from plundering the other ninetyper centum, and to make our judges and legislators obey the laws.