SLEEP. 609 



object at rest and yet exciting but little ; induce sleep, the 

 former acting by the ear, the latter by the eye ; and gentle 

 friction is equally effectual by means of touch. I know a lady 

 who often remains awake in spite of every thing till her husband 

 very gently rubs her foot : and, by asserting to a patient my con- 

 viction that the secret of an advertising hypnologist whom I allowed 

 to try his art upon the sleepless individual, and which he did for a 

 time successfully, was to make him gently rub some part of his 

 body till he slept, he confessed this to be the fact. Boerhaave 

 acted on the same principle in regard to another sense, when 

 he directed water to be placed near a sleepless patient, so cir- 

 cumstanced that it might drop into a brass pan. Gentle motion 

 acts by an impression on the same sense ; and a combination is 

 of course still more effective, whence experience has taught 

 nurses to rock, and otherwise gently agitate infants, while they 

 hum them to sleep. 



Most of the substances termed narcotic have a property of 

 inducing sleep and stupor ; they have the property of inducing 

 also giddiness, confusion, headach, delirium, and heat and throb- 

 bing : but some narcotics produce few or more of the other effects 

 rather than sleep. Narcotics lessen sensibility throughout and 

 indeed affectibility, possessing a general hostility to all vital pro- 

 perties. Yet many, if not all, stimulate in moderate quantities. 

 Opium augments the pulse and the heat, even in the head ; excites 

 the intellect and feelings ; gives headach ; and renders noise in- 

 tolerable : strychnine causes tetanic spasms : tobacco excites 

 sneezing : very many narcotics occasion smarting and burning. 



Impure air appears narcotic and disposes to sleep. Heat has 

 the same power, probably by relaxing ; for a certain proximity of 

 particles, and as it were tension of structure, is indispensable to 

 vigour and activity. Heat may also act by overcharging the 

 head with blood, partly through relaxation of vessels, partly, as 

 some think, by expanding the blood itself. Whatever overcharges 

 the head, as the reversed erect posture, has the effect of causing 

 heaviness and stupor; and thus by lying flat on a revolving mill- 

 stone, with the head towards the circumference, the centrifugal 

 force accumulates blood in the head sufficient to produce sleep and 

 at last apoplexy. Whatever else than blood compresses the brain 

 has the same effect; for instance an accumulation of serum, depres- 

 sion of bone, and, when the bone has been deficient in an individual 



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