The misconception regarding the nature of hypnosis and it’s connection to sleep has given rise to the idea that people do not remember what goes on during a hypnosis session. However, unless there is a specific suggestion to forget and a willingness by the client to forget then spontaneous amnesia is highly unlikely.
Just as a hypnotised subject cannot be forced to do something that is against their personal moral code, they cannot be forced to forget something if they feel it is important. The client may forget things that take place during hypnosis but this is as likely to be a poor memory as it is the ‘power of hypnosis’.
Many hypnotherapy tapes will plant suggestions about forgetfulness into the session, and there is a trend within Hypnotherapists to do the same, however there is no practical reason to include this as a suggestion and the client may simply ignore the suggestion in the first place.
The hypnotised subject is neither asleep, nor under anyones control. If they want to remember what goes on then they will and if they want to forget then they will, the suggestion by the hypnotist (like all suggestions) may sway the client if they were uninterested in whether they remembered or not, but that is down to the individual being hypnotised and not to the hypnotist.