Hypnosis is an altered state of awareness where the person in trance tends to get absorbed in the object of awareness with relative suppression of peripheral awareness. There is a change in the brain wave activity, similar to that time just before sleep when the alpha state is entered. Brain's waking state is beta state, just as you are going to sleep it changes to alpha and then to theta and onwards to delta which is a state of deep sleep. The alpha state is a very dreamy, pleasant state in which the mind is very open to suggestions/ visualizations and creating a rich sensory experience. 

Re-scripting or Re-framing is effected by giving necessary post-hypnotic affirmations and suggestions to bring about desired behavioural changes in the patients.