By and by the clock strikes eight or nine, and your mother says,
"Children, time to go to bed!"

Sometimes you will have just come to the interesting point in the
story, and would give anything to go on and finish it. But often you
will be just nodding over your book, or beginning to wonder why the
story is not quite so interesting as it was, or why the lines seem to
be running into one another, and the book inclined to swing up and
bump your nose.

If you have had a lively, busy, happy day, you are quite sleepy enough
to be ready for bed--that is, if you could drop into it with all your
clothes on, without all the bother and fuss of undressing. So you pull
yourself together bravely and answer, "All right, mother," and say
"Good night" to everybody, and upstairs you go.

Of course, you must take off your clothes, because you would find them
most uncomfortable to sleep in. Besides, the little pores all over
your skin have been pouring out perspiration all day long; and a great
deal of this has been caught by your clothes, just as it is caught by
the bedclothes while you sleep.

So it is a good thing to take off your clothes, and let your skin be
well aired and cooled. Don't leave your clothes all in a heap on the
floor just where you happen to shed them, but hang them up over the
back of a chair or on pegs, so that the air can blow through them all
night long and sweeten and clean and dry them. Clothes that are worn
continuously become sour with perspiration, and for this same reason
your mother gives you regularly, once or twice a week, clean underwear
and clean shirts or dresses.