118 PHYSIOLOGY AND TEMPEKANCE. 



requires careful attention. No child or youth should be 

 allowed to isolate himself. 



The same uniformity of exercise in brain and body gener- 

 ally must be observed all through the active years of life. If 

 the ardent student, in preparing himself for an examination, 

 fails to take physical exercise and give his brain an oppor- 

 tunity to rest, the chances are he will not only fail in his 

 examination, but permanently impair his mental strength by 

 the over-work of the brain. 



16. Rest and Sleep. The necessity for rest at stated 

 periods is most imperative. Brain work will be better done 

 when due attention is paid to regular rest. It is the same as 

 in the use of muscles. The skilled workman can continue his 

 employment only for a certain time. The laborer does more 

 and better work when he takes an occasional rest. Besides 

 this voluntary rest of the brain, nature has provided a rest 

 which must be taken by everyone. In sound sleep the brain 

 gets complete and perfect rest. Any attempt to shorten the 

 hours of unconscious repose is a violation of the laws of 

 health. Nature will not be cheated of its "sweet restorer, 

 balmy sleep." 



But sleep is also essential for body rest and for repair of 

 the whole system. During those restful hours in bed, the 

 circulation is lowered and the heart-beats are fewer. Jut 

 as it is less tiring for us to walk than to run, so is it much 

 easier for the heart to beat at the rate of fifty or sixty times 

 a minute, as it does in sleep, than at seventy or eighty when 

 we are moving about. And again, while we are asleep nature 

 is busily at work building up and repairing the tissues, and 

 restoring the energy we have exhausted during the day. 



The amount of sleep demanded by nature is not the same 

 in all persons. More sleep is necessary for the young than 

 for the old, and for those whose employment is arduous than 



