4 2o POPULAR SCIENCE MONTHLY. 



into the night. While a certain number of hours of consecutive sleep 

 are imperative for full health, these can not be dogmatically determined 

 except by carefully weighing circumstances, which vary. Lumber men 

 on the ' drive ' maintain excellent health on the smallest amount of 

 sleep, during the most trying circumstances, after intense physical 

 exertion so long as the spring daylight lasts, often wet to the skin, 

 with little or no bedclothes or protection at night from freezing 

 weather and fed irregularly, often insufficiently. Armies, exploring 

 parties and others have similar experiences, and suffer no distress for 

 days and weeks, the men often actually gaining in health, seldom 

 losing. If the circumstances be cheerful, such competition, overcom- 

 ing the forces of nature, is salutary. If peril, strained attention or 

 tyrannous officers complicate the conditions, ill health may appear 

 early and is then often severe. 



When to sleep is again a matter of opinion. Early rising is by 

 common consent a salutary custom, especially when the day comes early, 

 not otherwise. It is agreed that more sleep is required in winter than 

 in summer. The best sleep is had during the hours of darkness. 

 The mind is clearest in the early morning, and those who can utilize 

 this period for intellectual work are capable of turning out the best 

 products. Some can not do so, or think they can not, and yet furnish 

 excellent results. 



The sleeping room should be cool, abundant air being always ad- 

 mitted. This should not be interpreted to mean that the room may 

 safely remain intensely cold. In the modern treatment of tuberculosis 

 fresh air is recognized to be imperatively needed all day and all night. 

 Artificial heat can, and should, be supplied along with the fresh air, 

 till the temperature of the room be at or near 50° F. or 55° F., for 

 some even 60° F. Above this no one in health is likely to sleep in 

 perfect comfort. Babies and invalids need a heat of from 60° F. to 

 70° F., even more at times, yet all require the fresh air, or fullest 

 ventilation. 



Fever patients, even those suffering from pneumonia or bronchitis, 

 may sleep with safety and great advantage in a thoroughly ventilated 

 cool room and with no more covering on them than is needed for 

 protection from sudden changes of temperature which might send 

 their body heat down below normal. It is needless to particularize 

 as to the offensiveness, deleteriousness, of the body and lung exhalations 

 emitted by those asleep. This is more than apparent, it is actually 

 greater by far than when awake, and demands prompt removal and an 

 abundance of good air to replace that which is vitiated. There are 

 those who still cling to the shred of demon influence which causes 

 them to ' dread the night air ' when spirits range and goblins weave 

 evil spells; when diseases come wafting in at open windows, keyholes 



