If i played a hypnosis tape in the background while i am sleeping, will it work?

No . . . or maybe: Sleep learning has been researched a great deal in the past. It does not work, as a general rule. But, if someone goes through the motions to learn or be affected by a hypnosis tape while sleeping, perhaps it would benefit the person during those brief moments of waking while in bed. Positive processing of already learned information while sleeping takes place constantly, however.

Typically: Playing an hypnosis tape while sleeping works on the subconscious directly bypassing the conscious...It'll work as well if not better.