BONES, MUSCLES, EX 



strength, need from seven to nine 



of sleeping create a difference of necessity^Tor a time at 



least, and cannot easily and suddenly be broken. 



742. The sleep in the day does not compensate for the 

 loss of the niyht sleep. The soldiers who rested in the day, 

 and marched at night, had as much sleep as the others, who 

 slept at night ; and yet they suffered much more from sick- 

 ness and exhaustion. ( 738, p. 321 ) The most perfect sleep 

 and refreshing rest is obtained in the stillness of darkness, 

 when all nature reposes ; and it is all in vain that any one 

 struggles against this law of his being. He may sleep in the 

 day, and labor or watch in the night, but his waking hours 

 are then not so bright, nor is his energy of life so great, as 

 otherwise it would be. 



743. There are few who do not, now and then, devote a 

 night, or a part of a night, to some labor, to travel, to parties of 

 pleasure, or to watching with the sick. None of these escape 

 the penalties that always follow the violation of the law of 

 rest. Whatever may be the time required by habit, or the 

 constitution, for sleeping, for the recovering of exhausted 

 power, that time cannot be shortened without impairing, in 

 some measure, the strength and activity of the next day. 

 With less than the required quantity of sleep, the body is not 

 completely refreshed, nor has it the full energy for action. 

 If each day is expected to accomplish its entire work, each 

 night must have its complete rest; and whatever is taken 

 from the sleep must be taken from the power of labor. If 

 any one cannot retire at his accustomed hour, and still wishes 

 to have his usual power of action on the next day, he must 

 protract his rest in the morning as much as it was shortened 

 at night. 



744. During sleep, the circulation is more feeble, the res- 

 piration is slower, and the heat is generated less rapidly than 

 in waking hours, ( 436, p. 187,) and, consequently, we are 

 less able to resist the effects of 'cold; and if they exposed to 

 a current of air, we are more liable to suffer than when we 

 are awake, We therefore sleep under more clothing in the 



