About a year ago I composed the music for a series of 1 hour hypnotic sessions for a professional hypnotist friend of mine. The idea was for the folk who had already had a real session with him to help with such things as giving up smoking or anxiety, to have something they could play to themselves whenever they felt like relapsing.
He had already recorded his voice which comprised 3 distinct sections; firstly he slowly put the listener into a deep hypnotic state, then he implanted the relevant suggestions, then he slowly brought the listener back to "reality".
Musically and sonically, I followed his voice, ie when he was putting the listener into a trance he would "walk" them along a beach, so we used waves, birds etc. When he was talking about the terrible things smoking does to you, the music would reflect this (subtly though, of course), when he talked about how great you feel after giving up smoking, the music would have a more positive feel etc etc. Obviously though the general vibe of the music was normally very calm and relaxing.
Another important aspect was the use of sound waves for entrainment. specifically Alpha , Beta and Theta waves for each part of the hypnosis. Alpha waves are used for relaxation, Beta for attention, and Theta for Deep meditation.
There is an excellent article
here
Lastly though let me point out that this was a VERY time consuming excersise to get right!!!
