Working with a state of deep relaxation, in a medical practice, towards a goal agreed in advance. It has nothing to do with stage hypnosis.
The hypnotic state is not sleep and it is not a loss of control. You hear everything, you remember everything, you can talk to me and you can stop whenever you want. The difference from ordinary waking is how tightly attention gathers around one single thing, rather like what happens when you are reading a good book and stop hearing the conversation in the room.
I am a medical hypnotherapist, certified in the United States. "Medical" is the important word: I use it as one tool within a consultation, with a person whose history I know, not as a method on its own and never in place of treatment prescribed by someone else.