SLEEP; NARCOSIS 

 AND ALLIED PHENOMENA 



THE conditions that favour sleep are stated by 

 Halliburton to be : 



(1) A diminution of the impulses entering the central 



nervous system by the afferent channels, and 



(2) Fatigue, as this diminishes the readiness of the 



central nervous system to respond to stimuli. 



" Of the parts of the central nervous system," he adds, 

 ** the spinal cord is always less deeply affected than the 

 brain, but even the brain is never entirely irresponsive. 

 . . . Sensations of sound appear to be the last to dis- 

 appear as sleep comes on, and the first to be realised on 

 awakening." 



Some distinction must, I think, be drawn between the 

 afferent channels. Sensory nerves cannot be taken together 

 as a whole. The Optic as well as the Auditory nerves are 

 extensions of the brain and the latter should, in my view, 

 be as responsive to light as to sound. 



The logical outcome of my own work upon the subject 

 is this : 



Consciousness is in direct ratio to brain potential. Anything 

 that interferes with the supply of energy to the brain or with 

 the electrostatic capacity of the cells of the brain must diminish 

 consciousness. It is merely a question of degree. 



Howell is not far from the truth in attributing the sleepi- 

 ness which follows a heavy meal to the mechanical effect 

 of a dilatation of the abdominal vessels in producing a 

 diminished blood flow through the brain but he is, in my 

 opinion, wrong in believing the sleep that normally comes 

 on at the end of the day to be produced by cerebral anaemia 

 following dilatation of the blood-vessels of the skin, although 

 that may be a contributory cause. The true explanation 



