Hypnosis transports some people beyond serenity and absorption to a state of pure silliness. A solemn voice whispering to relax, breathe deeply and imagine a waterfall can bring to mind high school seances, Ouija boards, Woody Allen routines.

Yet the very same technique, the same voice, can move others to climb mountains. After a fall on a climbing expedition that mangled her ankles, Priscilla Morton, a 48-year-old New Orleans social worker and mountaineer, discovered that she was afraid to step off the curb and onto the street, much less climb again.

Using a program of hypnosis, she was able to ascend to the 19,347-foot summit of Mount Cotopaxi in Ecuador. Self-hypnosis "was the only way I could deal with the fear, the cold, the steepness, the exhaustion," Morton said.

Once mainly the province of entertainers, mystics and New Age healers, hypnosis is now gaining a foothold in mainstream medicine. At teaching hospitals such as those at Mount Sinai School of Medicine in New York and Harvard Medical School, hypnotists work with some surgical patients to help speed recovery. Many of the United States 1,000 or so certified hypnotherapists now get referrals from physicians on cases ranging from irritable bowel syndrome and heart disease to managing the pain of childbirth and cancer. In some studies, 50 percent to 70 percent of people who have tried it say hypnosis has helped them to feel better or heal faster. Such reports have encouraged its use for everything from weight loss to smoking cessation, with varying results.

But is the evidence strong enough to justify sessions that can cost $100? Most doctors are skeptical. For every person who learns to manage chronic pain, they say, several others manage only a yawn or a shrug. To earn widespread respect, hypnotherapists are going to have to reach more people, more consistently. "At this point, the therapy is certainly not well accepted by most physicians and surgeons," said Guy Montgomery, an assistant professor of biobehavioral medicine at the Mount Sinai School of Medicine.

The answer may be to teach hypnotizability, or suggestibility, as it's sometimes called. In more than a dozen studies over the last decade, men and women of various ages demonstrated they could learn to fall into a hypnotic trance more easily and deeply.

"Now the idea is to find what is most effective in getting them there, from a low level of suggestibility to a higher one," said Steven Lynn, a psychologist at the State University of New York at Binghamton who's conducting a large federally funded study on the subject. "You do that and you not only increase the number of people who would benefit but also widen the range of its applications."