PHYSIOLOGY OF SLEEP LEGENDRE. 593 



tion; still, the perspiration is then profuse, and Sanctorius states that 

 one perspires as much during 7 hours of sleep as in 14 hours when 

 awake. The kidneys are active at night and the urine in the morning 

 is generally denser than in the daytime. According to M. Bouchard, 

 who studied the effect of urinal poisons by injecting them into ani- 

 mals, those formed during sleep are convulsive and those formed when 

 awake are narcotic. By their mixture much of the poisonous effect 

 is lost. 



Respiration is modified during sleep. It is easy to observe this in 

 the case of those who snore, although the cause of snoring is little 

 known. Generally the respiration is retarded during sleep, being 

 deeper and more regular. In order to study this carefully, Mosso 

 applied to his chest a pneumograph, which indicated the respiratory 

 movements during sleep as well as when awake, and he established 

 the fact that the inspirations are longer arid the expirations shorter; 

 the thoracic movements are greater than the abdominal ones; the 

 rhythm is modified and from time to time the inspirations are replaced 

 by distinct series, by pauses, or by more feeble respirations. Respira- 

 tory changes have been studied thoroughly by Pettenkofer and Voit, 

 who used for that purpose a chamber of 12 cubic meters capacity 

 made of sheet iron, in which a man could remain for several days, 

 as th,e ventilation was regulated by two suction pumps. The atmos- 

 phere was analyzed as it came from ihe room and the amount of 

 carbon dioxide eliminated was found to be less during sleep. St. 

 Martin, who made his experiments on a turtledove, reached the same 

 conclusion. This diminution of the amount of carbon dioxide exhaled 

 may be due simply to cerebral repose in the absence of any muscular 

 action, or to other causes. M. Raphael Dubois has held the theory 

 that the decreased exhalation of carbon dioxide is in proportion to 

 an accumulation of the gas in the blood, which acts as an anesthetic 

 up to a certain point, and then excites the centers of wakefulness. 

 The body temperature generally decreases during sleep. Marie de 

 Manaceine has observed that it falls as low as 36.45° C. during the 

 summer and to 36.05° C. during winter, the lowest temperature 

 occurring between midnight and 3 o'clock in the morning. The 

 temperature of the brain also diminishes equally, according to observa- 

 tions by Mosso, which will have our attention presently. 



The heart action is retarded during sleep. Former investigators 

 discovered this by observing the pulse, and more recently this has 

 been confirmed by definite experiments. Mosso, by the use of 

 suitable instruments, was able to register the pulse in the forearm, 

 the leg, and the brain. Francois Franck observed that the contrac- 

 tions become weaker and the interval between heart beat and pulse 

 beat is greater than when awake; the arterial pressure diminishes, 

 38734°— sm 1911 38 



