"She made a soft sound with her nostrils, grinned ruefully and went to the controls. She set one of them for the patient's allotted sleep-command frequency and hit the master switch. There was a gentle explosion of sound - "white" noise, a combination of all audio frequencies, which served to disorient the dismantled patient, his reflexive obedience attempting to respond to all commands at once - for ten seconds, and then it automatically faded, leaving the 550-cycle 'sleep' note. The patient's face went blank and he lay back, slowly, his eyes closing. He was asleep before his head reached the pillow."
From "The Other Man".
By Theodore Sturgeon.
1956.