946 TIME REQUIRED FOR SLEEP. 



Med. and Surg. Journal for 1813-14-15.) Nor is 

 this latter fact at all surprising, when we reflect 

 that from three to four times more caloric is dis- 

 engaged by respiration during active exercise, 

 than when we are at rest. Nor is it difficult to 

 comprehend, why the action of the heart is more 

 strong and frequent in the morning than evening, 

 when we reflect that more animal heat is ex- 

 pended by exercise during the day, than is ob- 

 tained from the atmosphere by respiration. 



It is said by M'Nish, that birds sleep less than 

 mammalia, and the latter less than man, who 

 requires more during winter than summer, and 

 more in cold than in hot climates. However 

 this may be, it is certain, that during the long 

 nights of winter, for some time before and after 

 Christmas, the cock frequently crows at intervals, 

 as if not disposed to sleep so long. During 

 the prime of life, men require from six to eight 

 hours sleep, if we except those of large chests, 

 vigorous constitutions, and sanguine tempera- 

 ment, who are able to endure great muscular 

 and intellectual exertion with much less repose, 

 than individuals of the phlegmatic temperament. 

 During the most active period of their lives, Alex- 

 ander, Julius Caesar, Napoleon, Washington, the 

 Duke of Wellington, Lord Brougham, and many 

 other distinguished men, have not slept above 

 four or five hours in the twenty-four. But nothing- 

 tends more certainly to injure the constitution 

 and shorten life, than a want of sufficient sleep, 



