HOW TO SLEEP 



as a frightful reality, which perhaps will not vanish till 

 other channels of the brain have been aroused to ac- 

 tivity, bringing consciousness with its wide range of 

 corrective perceptions and memories. 



If, as we thus assume, the dream is the mental ac- 

 companiment of all inco-ordinate activity of the brain, 

 it is important to know what causes such ill-timed and 

 ill-adjusted activity. Like all other organic activities, 

 it is a response to external stimuli. But these stimuli 

 may be in operation at the moment or may have operated 

 during the period of waking to produce mental anxieties 

 that will not now allow the brain to sink into profound 

 restfulness. Stimuli that act directly are unusual 

 sounds, the noxious air of a badly ventilated room, a 

 cramped condition of a member of the body, irritative 

 conditions of the digestive organs, and the like. In the 

 present sense, any portion of the body outside the skull 

 may furnish an external stimulus to the brain; and 

 the stimuli which produce dreams probably come most 

 often from within the organism. 



It is evident that the condition of the brain itself will 

 largely determine the exact result of any disturbing 

 stimulus that may come from any source during sleep. 

 During profound sleep, a very active stimulus may fail 

 to produce a response sufficient to be recorded in a 

 dream; while later on, after the brain has partially 

 recuperated, a much lighter stimulus may serve to 

 introduce a series of dreams. It must be obvious, 

 too, that during the later hours of sleep, when the entire 

 brain is nearer the waking-point, activity of any isolated 

 brain tract will tend to spread to other tracts, thus 



