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In the Journal of Experimental Medicine for May, there appears an experimental investigation upon the physiology of sleep, by W. H. Howells of Johns Hopkins University. His experiments were made to ascertain the variations in the volume of the arm during sleep by means of a plethysmograph, and the results indicated a vasomotor dilatation in the arm, which the experimenter attributes to a relaxation of tone in the vascular apparatus of the skin, a diminished peripheral resistance in the skin area and a corresponding lower arterial pressure and blood supply to the brain. This interpretation of his results leads the author to adopt a theory of sleep which he thinks is new in some of its features, and which he states as follows: "The immediate cause of normal sleep lies in a vascular dilatation (of the skin) that causes a fall of blood pressure in the arteries at the base
THE LATEST THEORY OF SLEEP.. JAMA. 1897;XXIX(1):39–40. doi:10.1001/jama.1897.02440270045007