NIGHT AIR 189 



weather, and it has the further advantage of enabling 

 one to avoid the depressing and weakening effects of 

 overheated rooms. 



Night air. Another difficulty in the way of ade- 

 quate ventilation, which is fast being overcome, is the 

 fear of night air. Years ago, many persons were accus- 

 tomed to shut their sleeping rooms up tightly, lest "the 

 poison of the night air" should harm them. To-day, 

 however, it is recognized that the night air is as whole- 

 some as that of the day, from which it differs only in 

 temperature. The restfulness and recuperation of sleep 

 depend very largely upon having the freshest air possi- 

 ble in the sleeping room, in order to furnish the tissues 

 with all the oxygen that they need for repairing the 

 inroads which the day's activity has made upon them. 

 For this reason, the bed should always be far enough 

 from the wall to permit the free circulation of air about 

 it, and the windows should be wide enough open to admit 

 perceptible currents of air. In cold weather, the old- 

 fashioned nightcap is most useful, since it protects the 

 head from the drafts which are inseparable from a well- 

 ventilated sleeping room. 



Malaria. Malaria, which was formerly attributed to 

 the night air, is now known to be due to the transmission 

 of disease germs by the bite of a certain mosquito, the 

 anopheles, which is active at night. The moral, there- 

 fore, is not to keep out the night air but to protect 

 against insects. 



Dust, a source of disease. Our present knowledge 

 of the way in which disease is spread, has shown us that 

 one of the great menaces to health is the breathing of 

 dust-laden air. The dusty air of cities is so contami- 

 nated by the dried excretions of animals and of human 

 saliva that it is undoubtedly responsible in thousands. 



