SLElfP-WAKlNG. 627 



commence : nay, coherency, after continuing a long while, often 

 terminates in an absurdity on the same subject. The power of 

 volition, whether over our feelings and ideas or muscles, in sound 

 sleep can be but moderately exerted ; but its diminution has 

 endless degrees. We may have little or no command over our 

 thoughts, or we may have much, as when we reason, calculate, 

 or compose well. We have all shades of amount of power over 

 our muscles : we breathe, cough, move our head, limbs, and even 

 our trunk, more or less, in ordinary sleep ; people forcibly roused 

 frequently get out of bed and begin dressing before they know 

 where they are or what they are about; and, when overcome with 

 sleep in the midst of forced exertion, will continue standing or 

 walking or even moving their fingers at their work. Some- 

 times we will, in vain, as when awake. When awake, we often 

 make great efforts in vain to detain particular ideas and under- 

 stand or produce, but find we cannot fix our attention to the 

 point, or, if we do, that our cerebral organs are incapable of 

 work ; sometimes we will motion without effect. So in sleep, not 

 only is our will generally feeble, but sometimes strong yet un- 

 obeyed. We strive in vain to detain thoughts, or, if we succeed, 

 still certain faculties prove powerless. We may will much ex- 

 ertion strenuously, but the part of the nervous system connected 

 with the central extremities of the voluntary nerves is incapable 

 of being stimulated by that which is endowed with mental power. 

 In that imperfect sleep called night-mare, we will violently in 

 vain, but cannot move a muscle, nor utter a cry. Persons believe 

 that, if they can but move or even cry out, they shall recover 

 themselves, mistaking effect for cause : they move and cry out 

 the moment they have recovered. 



The phenomena of partial sleep are seen more remarkably in 

 the state called somnambulism, or sleep-walking, than in common 

 dreaming. The term sleep-waking, or somno-vigilium, has been 

 proposed, and is very appropriate, because in this state patients 

 may not walk, or may even be unable to walk. The individual 

 is capable of no impression from his external senses, or from one 

 or some of them only, and, if capable, either perfectly or in 



2 Dr. Darwin (Zoonomia, vol. i. sect. 18. p. 286.), and after him Prof. Du- 

 gald Stewart, contended that, in sleep, volition was suspended. Dr. T. Brown 

 refuted them in his Observations on the Zoonomia' 



T t 3 



