109 



stress, stimulation of the cardiac sympathetic together with 

 a high blood pressure — conditions which favour ventricular 

 fibrillation. 



A possible discharge of adrenaline into the circulation 

 under emotional excitation also comes into question, though 

 the importance of such discharge or its existence has been 

 denied by Stewart and Rogoff, in opposition to the well 

 known work of Cannon and de la Paz. The time incidence 

 of attacks of anginal pain may obviously be determined by 

 similar conditions. 



Conclusions. 



It is clear that the foregoing facts must be taken as pro- 

 foundly modifying the simple conception of night as the time 

 of r-est, and sleep as a condition in which quiescence prevails 

 and recuperative changes go on, restoring the bodily and 

 mental capacities which have become more or less reduced 

 at the end of the hours of work and wakefulness — a period 

 of repose also attended by sedative and beneficial effects on 

 many morbid conditions. This conception, while true as 

 regards undisturbed or sound sleep, has to be qualified by 

 the consideration that night and sleep are occasionally the 

 season of acute reflex and emotional disturbances which, in 

 the peculiar conditions present, induce very pronounced 

 effects on the circulatory system, throwing a formidable 

 strain upon its weak points, whether these be cardiac, with 

 susceptibility to fibrillation or anginal pain, etc., or arterial, 

 with risk of rupture. 



In this way the individual may, during the nocturnal 

 period of assumed repose, be subjected to suddenly developed 

 stresses, as estimated by the rise of blood pressure (even as 

 measured after awaking when it is falling) and the evidences 

 of increased heart action, far beyond what is involved in 

 ordinary muscular exercise gradually initiated — for example, 

 walking, cycling, slow ascent of stairs, straining, or mental 

 excitement in certain degrees. Thus haemorrhages, the 

 onset of anginal attacks, and other disturbances in the night 

 can be readily accounted for; also sudden death, probably 

 due to ventricular fibrillation in most instances 



In the light of these observations it is easy to understand 

 how in certain circumstances death may come like a thief 

 in the night to a susceptible person living with circulatory 

 conditions that approach the danger line, though these con- 

 ditions may, in favourable circumstances and barring fresh 

 developments, be compatible with many years of moderately 

 active life. 



Literature. 

 Brooks and Carroll : Arch, of Int. Med., August 15th, 1912. 

 C. Muller : Acta Medico Scandinavica, Stockholm, 1921, Iv, 443. 

 Blume : Ugeskrift for Laeger, Copenhagen, 1922, Ixxxiv, 1126 

 Schneider : Virchow's Archiv, 1896, xvi, 95. 



Watson and Finlayson : Glasgoiv Med. Jonrn., New Series, vi, 171. 

 MacWilliam : British Medical Journal, 1923, ii, 215. 

 Cannon and de la Paz : Amer. Jotirn. of Physiol., 1910, xxxii, 44. 

 Stewart and Rogoff : Jonrn. of Exper. Med., 1916, xxiv, 709. 



