Sleep-learning (also known as sleep-teaching or hypnopædia) attempts to convey information to a sleeping person, typically by playing a sound recording to them while they sleep.
The art of teaching someone a lesson in their sleep so that they can remember it when asked.
For me, hypnopaedia and Music are very much alike. For example, whenever I fall asleep listening to music, the next morning when I wake up, I will have the song stuck in my head. I will be singing it aloud (non intentionally,) but when someone asks me what song it is, or what the lyrics are, I have no clue.