i 64 OF SLEEP. SECT. XVIIL 1 6. 



increafe of irritability to internal ftimuli, or of fenfibility, during 

 fleep mud occafion them to commence at this time. 



Debilitated people, who have been unfortunately accuftomed 

 to great ingurgitation of fpirituous potation, frequently part 

 with a great quantity of water during the night, but with not, 

 more than ufual in the day-time. This is owing to a beginning 

 torpor of the abforbent fyftem, and precedes anafarca, which 

 commences in the day, but is cured in the night by the increafe 

 of the irritability of the abforbent fyftem during ileep, which 

 thus imbibes from the cellular membrane the fluids, which had 

 been accumulated there during the day ; though it is poffible 

 the horizontal pofition of the body may contribute fomething to 

 this purpofe, and alfo the greater irritability of fome branches 

 of the abforbent veflels, which open their mouths in the cells of 

 the cellular membrane, than that of other branches. 



As foon as a perfon begins to fleep, the irritability and fenfi- 

 bility of the fyftem begin to increafe, owing to the fufpenfion of 

 volition and the exclufion of external (timuli. Hence the ac- 

 tions of the vefleJs in obedience to internal ftimulation become 

 ftronger and more energetic, though lefs frequent in refpedt to 

 number. And as many of the fecretions are increafed, fo the 

 heat of the fyftem is gradually increafed, and the extremities of 

 feeble people, which had been cold during the day, become 

 warm. Till towards morning many people become fo warm, as 

 to find it neceflary to throw ofF fome of their bed-clothes, as 

 foon as they awake ; and in others fweats are fo liable to occur 

 towards morning during their fleep. 



Thus thofe, who are not accuftomed to fleep in the open air, 

 are very liable to take cold, if they happen to fall afleep on a 

 garden bench, or in a carriage with the window open. For as 

 the fyftem is warmer during fleep, as above explained, if a cur- 

 rent of cold air afFedls any part of the body, a torpor of that part 

 is more effedlually produced, as when a could blaft of air through 

 a key- hole or cafement falls upon a perfon in a warm room. In 

 thofe cafes the affefted part poflefles lefs irritability in refpeft to 

 heat, from its having previoufly been expofed to a greater ftim- 

 ulus of heat, as in the warm room, or during fleep ; and hence, 

 when the ftimulus of heat is diminimed, a torpor is liable to en~ 

 fue 5 that is, we take cold. Hence people who fleep in the 

 open air generally feel chilly both at the approach of fleep, and 

 on their waking ; and hence many people are perpetually fub- 

 jel to catarrhs if they fleep in a lefs warm head-drefs, than that 

 which they wear in the day. 



1 6. Not only the fenforial powers of irritation and of fenfa- 

 tion, but that of aflbciation alfo appear to al with greater vig- 

 our 



