The theory of hypnosis here formulated postulates certain psychophysiological mechanisms, especially the ascending reticular activating system, through which interpersonal and intrapersonal forces operate to achieve and maintain the hypnotic state. From this theory it can be predicted that certain drugs, such as the phenothiazine derivatives, will render the chronically anxious patient more accessible to hypnosis whereas certain others, such as phenobarbital, will not. These predictions are in accord with the author's experience.
Louis J. West. PSYCHOPHYSIOLOGY OF HYPNOSIS. JAMA. 1960;172(7):672–675. doi:10.1001/jama.1960.03020070030009