Sleep-learning

Sleep-learning (also known as hypnopædia) attempts to convey information to a sleeping person, typically by playing a sound recording to them while they sleep.

This technique is often moderately effective at making people remember direct passages or facts, word for word. However, there is little to no evidence that a person undergoing hypnopædia is actually learning anything in the sense that the newly acquired knowledge is connected to other knowledge or conceptualized in any way.