The tendency in our country is to heat buildings too much. Europeans are both surprised and uncomfortable when they first enter our dwellings or public meeting places. The temperature in a dwelling should not be forced above seventy degrees Fahrenheit by means of artificial heating. The temperature required depends very much upon one's mental attitude and habits. Those who take enough exercise have good circulation of the blood in the extremities, and therefore do not need so much artificial heat. The best heating is from within. CHAPTER XXIV. SLEEP. A young baby should sleep almost all the time, and it will if intelligently cared for. Overfeeding is the bane of the baby's life and is the cause of most of its restlessness. The first few months the baby should be awake enough to take its food, and then go to sleep again. As it grows older it sleeps less and less. There is no fixed time for an adult to sleep. The amount varies with different individuals. The idea is quite prevalent that eight hours nightly are necessary. This may be true for some. Many do very well on seven hours' sleep, and even less. The great inventor, Thomas Edison, is said to have had but very little sleep for many years, and it is reported that when interested in some problem he would miss a night or two. Yet he has lived longer than the average individual and is now in good health. Very few have done as much constructive work as he. Many other prominent people have been light sleepers. As people grow older they require less sleep than they did in youth. It is not uncommon for septuagenarians to sleep but five hours nightly. Although we can not say how much sleep any individual may require, each person can find out for himself, and this is much better than to try to live by rules, which are often erroneous. Those who live as they should otherwise and select a definite hour for retiring and adhere to it, except on special occasions, get all the sleep that is necessary. They awake in the morning refreshed, ready to do a good day's work. During sound sleep all conscious endeavors cease. The vital organs do only enough work to keep the body alive. The breathing is lighter, the circulation is slower and in sound sleep there is no thinking. This letting up in the great activity of body and mind gives an opportunity for the millions of cells, of which the body is composed, to take from the blood what is needed to restore them to normal. During the day many of these cells become worn and weary. At night they recuperate. Hence undisturbed sleep is very important.