Sect. XVIII. 15. OF SLEEP. 163 



about twenty-two years of age, who feldom Sleeps mere than an 

 hour without experiencing a convulfion fit ; which ceafes in 

 about half a minute without any fubfequent Stupor. Lar^e 

 dofes of opium only prevented the paroxyfms, fo long as they 

 prevented him from Sleeping by the intoxication, which they in- 

 duced. Other medicines had no effect on him. He was gently 

 awakened every half hour for one night, but without good ef- 

 fect, as he foon Slept again, and the fit returned at about the 

 fame periods of time, for the accumulated fenforial power, which 

 occasioned the increafed fenfibility to pain, was not thus exhauft- 

 ed. This cafe evinces, that the fenfibility of the fyftem to in- 

 ternal excitation increafes, as our Sleep is prolonged ; till the 

 pain thus occafioned produces voluntary exertion ; which, when 

 it is in its ufual degree, only awakens us"; but when it is more 

 violent, it occafions convulfions. 



The cramp in the calf of the leg is another kind of convul- 

 fion, which generally commences in fleep, occafioned by the 

 continual increafe of irritability from internal Stimuli, or of fen- 

 fibility, during that State of our exiflence. The cramp is a vi- 

 olent exertion to relieve pain, generally either of the Skin from 

 cold, or of the bowels, as in fome diarrhoeas, or from the muf- 

 cles having been previously overflretched, as in walking up or 

 down lteep hills. But in thefe convulfions of the mufcles, which 

 form the calf of the leg, the contraction is fo violent as to occa- 

 iion another pain in confequence of theb own too violent con- 

 traction, as foon as the original pain, which caufed the contrac- 

 tion, is removed. And hence the cramp, or fpafm, of thefe 

 mufcles is continued without intermilfion by this new pain, un- 

 like the alternate convulfions and remiflions in epileptic fits. 

 The reafon, that the contraction of thefe mufcles of the calf of 

 the leg is more violent during their convulfion than that of oth- 

 ers, depends on the weaknefs of their an tagoniit mufcles ; for 

 after thefe have been contracted in their ufual action, as at every 

 ftep in walking, they are again extended, hot, as mod other 

 mufcles are, by their antagonists, but by ths.wcight of the whole 

 body on the balls of the toes ; and that weight applied to great 

 mechanical advantage on the heel, that is, on the other end of 

 the bone of the foot, which thus acts as a lever. 



Another difeafe, the periods of which generally commence 

 during our Sleep, is the aSthma. Whatever may be the remote 

 caufe of paroxyfms of aSthma, the immediate caufe of the con- 

 vulsive rcipiration, whether in the common aSthma, or in what 

 is termed the convulfive aSthma, which are perhaps only differ- 

 ent degrees of the fame difeafe, muSt be owing to violent volun- 

 tary exertions to relieve pain, as in other convulfions j and me 



increafe 



