Some Facts About the Physiology of Sleep13
N. A. Rozhansky investigated that form of sleep, or somnolent state, which apparently results from the influence of monotonous, indifferent stimuli, for example, the isolated environment in which the experimental animal is placed. When the animal is enclosed in an isolated chamber and placed in the stand, it gradually becomes drowsy, and then goes into deep sleep. Sleep also occurs under the influence of definite, active stimuli from which strong conditioned stimuli have been elaborated. In the wakeful state both the secretory and the motor reflexes are present. Immediately after the conditioned stimulus begins to act a secretion of saliva appears, and the dog takes the food as soon as it is offered. One of the customary methods of gradually dispelling sleep is to feed the dog at definite intervals.