OF SLEEP. SECT. XVIII. 3. 



that we fhould miftake the trains of imagination for 

 ideas excited by irritation ; as perpetually happens 

 to people debilitated by fevers on their firft awak- 

 ing ; for in thefe fevers with debility the general 

 quantity of irritation being diminiflied, that of fen- 

 fation is increafed. In like manner if the actions 

 of the (lomachj: inteftines, and various glands, 

 which are perhaps in part at lead caufed by or cate- 

 nated with agreeable fenfation, and which perpetu- 

 ally exift during, our waking hours, were like the 

 voluntary motions fufpended in our fleep ; the great 

 accumulation of fenforial power, which would ne- 

 ceflfarily follow^ would be liable to excite inflamma- 

 tion in them.- 



3. When by our continued pofture in fleep, 

 Jo me urieafy fenfations are produced, we either gra- 

 dually awake by the exertion of volition, or the 

 xnufcles connected by habit with fuch fenfations 

 alter the pofition of the body ; but where the fleep 

 is uncommonly profound,- and thofe uneafy fenfa- 

 tions great, the difeafe called the incubus, or night- 

 mare, is produced. -Here the defire of moving the. 

 body is painfully exerted, by the power of moving 

 it, or volition, is incapable of action, till we 

 awake. Many lefs difagreeable druggies in our 

 dreams, as when we wifli in vain- to fly from terri- 

 fying objeds, conftitute a (lighter degree of this dif- 

 eafe. In av/akkig from the nightmare I have more 

 than once obferved, that there was no diforder in 

 Hiy pulfe ; nor do I believe the refpiration i* labo- 

 rious, as forne have affirmed. It occurs to people 

 \vhoie ileep: is too profound, and fome difagreeable 

 fenfation exifts, which at other times would have 

 awakened them, and have .thence prevented the 

 difeafe of nightmare j as after great fatigue or hun- 

 ger with too large a fupper and wine, which oeca- 

 fion our fleep- to be uncommonly profound* See 

 No. i4> of this Sedion* 



4- &* 



