SLEEP AND ITS REGULATION. 415 



Weir Mitchell has written fascinatingly of disorders of sleep, 

 making absorbing reading for the profession as well as the laity. He 

 it was who described first the sensory shocks, strange feelings passing 

 along the body, culminating in some abrupt explosion, noise, odor or 

 vision. Vertigo is occasionally thus experienced, especially by those 

 who have felt it before. That mysterious malady called ' migraine' 

 sometimes occurs suddenly while asleep ' and hales the sufferer from 

 profound sleep to waking hours of misery.' 



Morbid or perverted sensations, numbness, ' pins and needles ' for- 

 mications and such like mild neuroses appear at times during sleep. 

 Limbs may seem ' dead,' sensation being temporarily lost and not in 

 any way which follows upon marked pressure interrupting the flow of 

 nervous impulses, but purely a phenomenon of sleep. These are more 

 common in the later hours of night, when the motor cells are restored 

 in part, losing irritability, the sensory cells being still excitable. 

 These discomforts may be referred to interruptions in the conductivity 

 of the spinal cord. Nocturnal psychoses, the night terrors of children, 

 nightmare, strange mental vagaries, changes in intellectual and emo- 

 tional balance, are of such wide variety that they can only be alluded 

 to ; each person of rich experience is able to recall instances. In these 

 conditions of distress much folly can be committed, and frequently is; 

 evil thoughts are thus engendered, which too often influence action 

 later. Sometimes imperative impulses arising in slumber drive one to 

 commit questionable or silly deeds. The imagination in some is thus 

 stimulated to utter weird statements, or to put on record what are 

 falsely estimated to be thoughts of deep significance. I recall reading 

 an incident in the early official life of Bismarck, who often thus wakened 

 in the night with the conviction that he had solved perplexing prob- 

 lems. On reducing to writing the ideas thus excited he found, on 

 perusal next day, that they were altogether fanciful. It is true, valu- 

 able ideas do come in dreams or in real temporary waking states. 



The sleep of early life is peculiarly sensitive to irritations of the 

 organs below the diaphragm, digestive or genital ; in later life to those 

 above, of the heart, blood vessels or lungs. In this connection we may 

 refer to dreams. The suspension of brain activity in sleep is only 

 partial; there prevails a certain amount of psychic life. Every nerv- 

 ous stimulus, sensation or idea leaves an impression, a trace, in the 

 cerebro-spinal system. Obscure motions, influences, irritants generated 

 in the organism, may afterward revive temporarily under some im- 

 pulsation of consciousness, as by afflux of blood. Each cell of the body 

 is endowed with more or less memory (Henle), for by this means are 

 preserved hereditary influences, the transmission of psychic and mental 

 characteristics, the after images of sensations. In this manner many 

 sounds, sights, feelings, which are partially conveyed to the sensorium, 



