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.