Ever since people went about the process of consciously trying to learn and remember things, they have wished for the ability to enhance their retention while they sleep. People were cajoled into purchasing books on tape that purportedly would help them learn foreign languages in their sleep, and many a student pulling an all nighter has wished for a way that they could grab a late night nap and still do some information cramming.
Although it is unfortunately not that easy, there is a great deal of evidence that indicates that our ability to retain information is strengthened by the sleep that we get, and recent studies have even shown that there are specific sensory inputs that can help us remember things better. It may sound crazy, but scientists have found that people who hear a specific song while they are putting an object away are better able to remember where they put it if that song has been played to them while they were asleep. And students attempting to learn a foreign language have remembered specific vocabulary words better when they have had those words played to them while they slept.
In the latter example, researchers working with German students put them through several lessons in Dutch, teaching them some simple words. They then asked the students to go to sleep, and while they were sleeping they played recordings of the words that had been learned to about half of the students. None of the students knew about the auditory prompts, but when the students were tested on the words later the ones who had heard the recordings in their sleep tested better. The students also were exposed to words in their sleep that they had not heard, and they showed no recognition of them on their test, so the researchers could tell that the role of hearing the words in their sleep was not to actually learn, but to better remember. In order to better pinpoint their results, the scientists also had a group of the students listen to recordings of the words as they were awake and walking so that they could determine whether the memory enhancement came from hearing the words or from sleep – those who heard the words while walking did not improve their scores.
In analyzing their results, the researchers concluded that our sleeping brains actually slow down during the night, and it is during these times when it is operating in slow motion that the brain is working its hardest, organizing our memories so that we can easily access information. Interestingly, an in-depth look at the German students who participated in the test showed that when the foreign words were played to them while they slept, their brains actually slowed down for longer periods of time. This led the researchers to the conclusion that the more slow wave brain activity our brain experiences, the better we remember things.
Another test involved students who were taught to play a song on a guitar and then napped immediately after their lesson. Some of the students were exposed to the same song that they had just learned being played to them while they slept, while others did not. Those students who heard the music while they were sleeping were better able to play the song after they woke up then those who had not been exposed to the music in their sleep.