You can't learn Japanese while you sleep by just playing tapes of people speaking Japanese, but if you are already studying Japanese, playing the tapes might help you better remember the stuff you've already studied.
This study involved subjects learning the positions of 50 photos of different objects on a computer screen. When each was shown, a related sound played on a speaker, such as glass breaking for a photo of a broken wine glass or a muffled explosion for dynamite. After 45 minutes of learning, the subjects were sent down for a nap. While they were asleep, researchers played the sounds associated with half the photos. When tested later, they remembered the positions of the photos the sounds of which had been played while asleep better than those that had not been played. None remembered having heard the sounds while napping.
"Our little experiment opens the door to many questions," (one of the authors) said.
Would high-school students do better on SAT tests if daytime studying was supplemented with sleep sounds at night? Would students learning foreign vocabulary words or other facts do better in the morning after listening to related information as they slept? Infants spend an inordinate amount of time sleeping, while their brains work over their recent experiences. Could an infant learn a first language more quickly if stimulation occurred during naps or overnight? What about an actor trying to learn lines or a law student trying to memorize numerous details of case law? Could playing sounds related to such learning improve the recall of relevant facts the next day?
