Vital power is renewed in sleep. Every living thing sleeps; men, animals, reptiles, fish, and insects sleep, and even plants have regular periods of slumber. And this is because it is in sleep that we come into such contact with the Principle of Life in nature that our own lives may be renewed. It is in sleep that the brain of man is recharged with vital energy, and the Principle of Health within him is given new strength. It is of the first importance, then, that we should sleep in a natural, normal, and perfectly healthy manner.
Studying sleep, we note that the breathing is much deeper, and more forcible and rhythmic than in the waking state. Much more air is inspired when asleep than when awake, and this tells us that the Principle of Health requires large quantities of some element in the atmosphere for the process of renewal. If you would surround sleep with natural conditions, then, the first step is to see that you have an unlimited supply of fresh and pure air to breathe. Physicians have found that sleeping in the pure air of out-of-doors is very efficacious in the treatment of pulmonary troubles; and, taken in connection with the Way of Living and Thinking prescribed in this book, you will find that it is just as efficacious in curing every other sort of trouble. Do not take any half-way measures in this matter of securing pure air while you sleep.