CHAPTER XXVIII. 



SLEEP AND DEATH. 



1. \SLEEP is the periodical and temporary suspension of 

 those functions that connect us with the external world. 

 Man is so constituted, that the functions of sensibility, vol- 

 untary motion, and the intellectual faculties cannot be in- 

 dulged for any length of time without fatigue. The nervous 

 energy, which seems essential to their exercise, becomes ex- 

 hausted ; the muscles can no longer contract ; the external 

 senses cannot receive impressions ; the brain, and conse- 

 quently the mind, becomes torpid ; and a person sinks into 

 a state of torpor and inaction, called sleep. 



S.rThe approach of sleep is announced by an internal 

 sensation, termed drowsiness,} which gradually increases in 

 strength, till at length it becomes irresistible. Great languor 

 of the muscles and heaviness of the eyes are experienced ; 

 the sight yields first ; next the smell ; then the hearing ; and 

 lastly, the sense of touch ; while at the same time, all the 

 internal sensations, such as hunger and thirst, are no longer 

 felt. The will ceases to control the functions that are under 

 its influence, till finally all power of volition is wholly lost. 

 Respiration is still carried on, but chiefly by means of the 

 diaphragm, which is an involuntary muscle ; it is, however, 

 somewhat slower, as well as the circulation, than in the 

 waking condition. , 



3. During perfect sleepj the functions of the brain are en- 

 tirely suspended. In such a state, dreams do not happen ; 

 for as the brain is in a state of complete inaction, the intel- 

 iectual operations are consequently dormant. {When the 

 brain is not in a state of complete repose, objects and images 

 may float confusedly through the mindj which are often the 

 result of external impressions imperfectly perceived, as they 

 excite but an imperfect reaction in the brain. 



