Experiments Show We Really Can Learn While We Sleep_Featured_, Science Thursday, June 28th, 2012
(Smithsonian) The average American sleeps some 7.6 hours a night—maybe not as much as one would like, but a number that still amounts to more 200,000 hours total over the course of a lifetime. What if there were some way to use all these hours to do something we don’t have the time to do while awake, like learn to play a musical instrument or speak a foreign language?
The idea that you can learn new things through some sort of magical mental osmosis while you sleep has long been wishful thinking. But a new study by Northwestern University researchers indicates that, depending on what we hear during the night, it is indeed possible to reinforce existing memories and enhance our recall after we wake up.
In the study, published today in the journal Nature Neuroscience, the research team first had participants learn how to play a pair of songs by pressing keys on a keyboard in a specific sequence. Then the test subjects were left in a dark, comfortable room to take a 90-minute nap. Once the participants were in slow-wave sleep—the deepest part of the sleep cycle, which the research team suspected was the stage most conducive to memory enhancement—one of the songs was played repeatedly. When tested after their naps, the participants consistently performed better at recalling and playing the song they had heard while sleeping, compared to the other tune.
This differs from the apocryphal concept of learning new information—say, a foreign language, or material for an upcoming exam—simply by listening to it during the night. “The critical difference is that our research shows that memory is strengthened for something you’ve already learned,” said Paul J. Reber, a psychologist at Northwestern and co-author of the study, in a press release. “Rather than learning something new in your sleep, we’re talking about enhancing an existing memory by re-activating information recently acquired.”
Additionally, the researchers measured brain activity during the sleep stage of the experiment. “We also found that electrophysiological signals during sleep correlated with the extent to which memory improved,” said lead author James Antony. “These signals may thus be measuring the brain events that produce memory improvement during sleep.”