p, the waste is
diminished, and the cells are more actively rebuilding the structure for
to-morrow's labor. The organic functions, such as are under the direct
control of the sympathetic nervous system,--circulation, respiration, and
digestion,--are diminished in activity during sleep. The pulsations of the
heart and the respiratory movements are less frequent, and the
circulation is slower. The bodily temperature is reduced, and the cerebral
circulation is diminished. The eyes are turned upward and inward, and the
pupils are contracted.

The senses do not all fall to sleep at once, but drop off successively:
first the sight, then the smell, the taste, the hearing and lastly the
touch. The sleep ended, they awake in an inverse order, touch, hearing,
taste, smell, and sight.

289. The Amount of Sleep Required. No precise rule can be laid down
concerning the amount of sleep required. It varies with age, occupation,
temperament, and climate to a certain extent. An infant whose main
business it is to grow spends the greater part of its time in sound sleep.
Adults of average age who work hard with their hands or brain, under
perfectly normal physiological conditions, usually require at least eight
hours of sleep. Some need less, but few require more. Personal
peculiarities, and perhaps habit to a great extent, exert a marked
influence. Some of the greatest men, as Napoleon I., have been very
sparing sleepers. Throughout his long and active life, Frederick the Great
never slept more than five or six hours in the twenty-four. On the other
hand, some of the busiest brain-workers who lived to old age, as William
Cullen Bryant and Henry Ward Beecher, required and took care to secure at
least eight or nine hours of sound sleep every night.

In old age, less sleep is usually required than in adult life, while the
aged may pass much of their time in sleep. In fact, each person learns by
experience how much sleep is necessary. There is no one thing which more
unfits one for prolonged mental or physical effort than the loss of
natural rest.

290. Practical Rules about Sleep. Children should not be played with
boisterously just before the bedtime hour, nor their minds excited with
weird goblin stories, or a long time may pass before the wide-open eyes
and agitated nerves become composed to slumber. Disturbed or insufficient
sleep is a potent factor towards producing a fretful, irritable child.

At all ages the last hour before sle