a"^ 



lieprmtedfrom the British Medical Journal, December 22nd, 1923 



SOME APPLICATIONS OF PHYSIOLOGY 

 TO MEDICINE. 



III.— BLOOD PRESSURE AND HEART ACTION 



IN SLEEP AND DREAMS: 



Their Relation to Haemorrhages, Angina, and 

 Sudden Death.* 



BY 



J. A. MacWILLIAM, M.D., F.R.S., 



PROFESSOR OF PHYSIOLOGY IN THE UNIVERSITY OF ABERDEEN. 



(From the Physiological Laboratory.) 



This is an important, and in some of its aspects an almost 

 unexplored, field of study, with an obvious bearing on many 

 questions. Precise data on the subject are naturally some- 

 what diflBcult to obtain. The present paper contains some 

 results of slowly accumulating observations carried on by 

 the writer as opportunities presented themselves over a long 

 series of years. 



Changes in Normal Sleep. 

 The slowing of the pulse rate (noted by Galen) and the 

 respiration during sleep has long been known to be accom- 

 panied by a lowering of bodily temperature, a great reduc- 

 tion in metabolic activity and heat production, depression 

 of reflexes, diminished secretion, etc. There is general 

 agreement as to a definite lowering of the systolic blood 

 pressure, varying in different conditions and as recorded 

 by different observers, but often amounting to 15 to 

 30 mm. Hg at the end of two hours' sleep ; the pressure 

 gradually rises in the later portion of the night's sleep. 

 Greater reductions have been noted in persons with high 

 pressures in the daytime. Thus some years ago Brooks 



*A communication on this subject was made to the International 

 Physiological Congress at Edinburgh on July 26th, 1923. Part I of this 

 series was published on January l3th, 1923 (p. 51), Part II on August 

 11th, 1923 (p. 215). 



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