If you dream that you are under the hypnosis, it shows that someone in your life has a very big influence. This person makes the decisions instead of you, or simply makes you think that you make a decision when you are actually making one. The dream suggests to take the responsibility for your own life.
Dream dictionary: Hypnosis dream meanings
To hypnotize a person indicates that your influence will be very strong on those around you. To be hypnotized predicts that you will have to submit for lack of power.