Excerpt of an article by Scott O. Lilienfeld and Hal Arkowitz in Scientific American, January 2009:
Studies confirm that during hypnosis subjects are not in a sleeplike state but are awake
The hypnotist, dangling a swinging pocket watch before the subject’s eyes, slowly intones: “You’re getting sleepy … You’re getting sleepy …” The subject’s head abruptly slumps downward. He is in a deep, sleeplike trance, oblivious to everything but the hypnotist’s soft voice. Powerless to resist the hypnotist’s influence, the subject obeys every command, including an instruction to act out an upsetting childhood scene. On “awakening” from the trance half an hour later, he has no memory of what happened.
In fact, this familiar description, captured in countless movies, embodies a host of misconceptions. Few if any modern hypnotists use the celebrated swinging watch introduced by Scottish eye surgeon James Braid in the mid-19th century. Although most hypnotists attempt to calm subjects during the “induction,” such relaxation is not necessary; people have even been hypnotized while pedaling vigorously on a stationary bicycle. Electroencephalographic (EEG) studies confirm that during hypnosis subjects are not in a sleeplike state but are awake—though sometimes a bit drowsy. Moreover, they can freely resist the hypnotist’s suggestions and are far from mindless automatons. Finally, research by psychologist Nicholas Spanos of Carleton University in Ontario shows that a failure to remember what transpired during the hypnosis session, or so-called posthypnotic amnesia, is not an intrinsic element of hypnosis and typically occurs only when subjects are told to expect it to occur.