384 MAURY OX SLEEP AXD DREAMS. 



conditions of sleep, while admitting that these ever 

 tend to graduate into more abnormal phenomena. 



The various epithets applied to sleep profound 

 sleep, heavy sleep, light sleep, broken sleep, &c. 

 express actual realities of state ; but these so mingled 

 with each other, so fitful in change, and so perplexed 

 by the vagaries of dreams and disturbing causes from 

 within and without, that even the sleeper himself is 

 generally at fault in defining them. ' I have not slept a 

 wink,' is often the piteous exclamation of the morning, 

 when only some short portion of the night has been 

 made wakeful and restless by disordered digestion, or 

 one of those compulsory trains of thought which fasten 

 pertinaciously on the mind, despite every effort to 

 shake them off. But, though we cannot measure the 

 amount of sleep by hours, or the consciousness of the 

 sleeper, there is much real difference in its degree in 

 relation to the great function of repair. A certain 

 quantity of work is to be done, but it is done at very 

 different rates. This diversity occurs in different per- 

 sons, and in the same person at different times. One 

 hour in one case may comprise as much of what is true 

 sleep, as two or many hours in another ; and the only 

 fair or probable test is to be found in the greater 

 or less difficulty of arousing the sleeper by external 

 action on the senses of touch and hearing. Individual 

 temperament of body and mind, habits of life, and the 

 immediate antecedents of sleep, are all concerned in 

 this matter. The Duke of Wellington, in that hour of 

 his recorded sleep on the field of Salamanca, when the 

 two armies were closely pressing to their conflict, pro- 



