HOW TO SLEEP 



the ringing of bells, the blowing of whistles, and the 

 like, do not disturb the sleeper after they have been 

 regularly experienced for a little time, and all such 

 sounds may be practically disregarded in considering 

 the therapeutics of sleep. 



The brain cannot guard fully against unusual and 

 hence unexpected sounds, and in almost any environ- 

 ment these furnish an occasional disturbing factor 

 against which there is no direct safeguard. But they 

 will disturb the sound sleeper far less than the light 

 sleeper, and will not ordinarily annoy one who has 

 acquired good habits of sleeping. The sleep of a tired 

 boy illustrates how fully the brain may be withdrawn 

 from responsive accord with the outer world, and 

 furnishes an object in truly profound and recuperative 

 sleeping. You might discharge a gun over him with- 

 out fully arousing him. Even if he stirs and partially 

 awakens, he will relapse at once into a deep sleep, and 

 the intruding stimulus will probably not be remembered 

 even as a dream. And the sleep of an adult who has 

 retained the good habits of sleeping which almost 

 everyone has in childhood, will be comparable to this. 

 He will not require so much sleep as the child, be- 

 cause he has only to make up the waste of the previous 

 day while the child must make up his day's waste and 

 add an increment for growth. But if the adult takes 

 only what sleep he really needs, and takes it in a per- 

 fectly normal way, his period of sleep will be approxi- 

 mately as profound as that of the child. 



That very few adults have perfect habits of sleeping, 

 goes without saying; that such habits are to be desired 



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