If the body be
properly covered, the animal heat is being conserved, and laid up for
expenditure during the waking hours that are to follow; the
respiration is reduced, the inspirations being lessened in the
proportion of six to seven, as compared with the number made when the
body is awake; the action of the heart is reduced; the voluntary
muscles, relieved of all fatigue, and with the extensors more relaxed
than the flexors, are undergoing repair of structure, and recruiting
their excitability; and the voluntary nervous system, dead for the
time to the external vibration, or, as the older men called it,
'stimulus' from without, is also undergoing rest and repair, so that,
when it comes again into work, it may receive better the impressions
it may have to gather up, and influence more effectively the muscles
it may be called upon to animate, direct, control."[11] An American
observer and physiologist, Dr. William A. Hammond, confirms the views
of his English colleague. He tells us that "the state of general
repose which accompanies sleep is of especial value to the organism,
in allowing the nutrition of the nervous tissue to go on at a greater
rate than its destructive metamorphosis.
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