Being hypnotized feels like you are about to fall asleep or when you first wake up.  The reason you feel this way is that you will be brought into a deep relaxed state and your brain waves will shift from Beta which is how our brain waves appear during regular consciousness to Theta brain waves which is how they appear when we are about to fall asleep.  When we are about to fall asleep and when we are asleep in dreamtime is when we can access our subconscious brain.  You are aware during the whole session.  Most people remember everything from a hypnosis session however there are a few that do not remember every detail.