Every shoe should be at least three-quarters of an inch longer, and from half to three-quarters of an inch wider, than the foot at rest, to allow proper expansion of these great "carriage-spring" arches. If children run free in the open air, either barefoot, or with light, loose, well-ventilated shoes, or sandals, they will have little trouble, not only with bunions, corns, "flat-foot," or lameness, but also with their backs, their gait, and their carriage. Easily half of our backaches, and inability to walk far or run fast in later life, to say nothing of over-fatness and dyspepsia, are caused by tight shoes.
SLEEP AND REST
Why We Need Rest. A most important element in a life of healthful exercise, study, and play is rest. Even when we are hard at work, we need frequent breathing spells and changes of occupation and amusement to keep one part of our muscles, or our brains, from poisoning itself. But after a time, in even the strongest and toughest of us, there comes a period when no change of occupation, no mere sitting still, will rest us; we begin to feel drowsy and want to go to sleep. This means partly that the fatigue poisons, in spite of fresh air and change, have piled up faster than we can burn them, so that we need sleep to restore the body.
All day long we are making more carbon dioxid than the oxygen we breathe in can take care of; while we sleep, the situation is reversed—the oxygen is gaining on the carbon dioxid. This is why the air in our bedrooms ought to be kept especially pure and fresh.
But the need goes deeper than this: sleeping and waking are simply parts of the great rhythm in which all life beats—a period of work followed by a period of rest. Continuous, never-ceasing activity for any living thing quickly means death. While externally the body appears to be at rest, the processes of growth and upbuilding probably go on more rapidly when we are asleep than when we are awake. The benefits of exercise are made permanent and built into the body during the sleep that follows it. The more rapidly young animals are growing, the more hours out of the twenty-four they spend in sleep. When you sleep, you are not stopping all the useful activities of your body and mind, you are simply giving some of the most useful and most important of them a chance to work. The only likeness between sleep and death is that in both the body is quiet and the eyes are closed. Really we are never more alive and growing than when asleep.
It is of the utmost importance that young children especially have all the sleep they need, and that is precisely all that they can be induced to take. The best rule for you, then, to follow, is to go to bed when you feel sleepy, and to get up when you wake rested. Every child under twelve should have at least ten hours of sleep, and every grown person eight, or better still, nine hours. Time spent in sound, refreshing sleep, is time well spent. If you cannot sleep well, it is a signal that something is wrong with your health, or your habits—a danger signal of great importance, which should be attended to at once. The best and only safe sleep-producer is exercise in the open air.
DISORDERS OF MUSCLES AND BONES
The Muscles and Bones Have Few Diseases. Considering how complex it is, and the never-ceasing strain upon it, this moving apparatus of ours, the nerve-bone-muscle-machine, is surprisingly free from disease. The muscles, though they form nearly half our bulk, have scarcely a single disease peculiar to them, or chiefly beginning in them, unless fatigue and its consequences might be so regarded. They may become weakened and wasted by either lack or excess of exercise, by under-feeding, or by loss of sleep; but most of their disturbances are due to poisons which have got into the blood pumped through them, or to paralysis or other injuries to the nerves that supply them.
The muscles of an arm, for instance, which has been lashed to a splint, or shut tightly in a cast for a long time, waste away and shrink until the arm becomes, as we say, "just skin and bone"; and the same thing will happen if the nerve supplying a muscle, or a limb, is cut or paralyzed.