A study appeared in a 1999 issue of Psychotherapy and Psychosomatics. It tested how good hypnosis was with helping people with psoriasis. 11 patients were involved in the study.....
All 11 received some form of hypnosis. The results were so good that the researchers said that hypnosis should be a form of treatment in those who are highly suggestible and who suffer from this ailment:
Source: Tausk, F. & Whitmore, S.E. (1999). A Pilot Study of Hypnosis in the Treatment of Patients with Psoriasis. Psychotherapy and Psychosomatics, 68(4): 221-5.
My Take: People are pretty much equally suggestible as long as they are willing to follow instructions and are of normal intelligence. My clients and those of my collegues almost always reach at least the threshold of somnambulism when they follow the directions we give them. Most studies, such as this one, are done using out-dated techniques. My bet is that almost all of the subjects would do well if the hypnotists had advanced training even the ones that the study believes are less suggestible.