Playing music while you sleep can help improve your ability to play the same tune, new Northwestern University research suggests.
The research supports existing evidence that memories can be reactivated during sleep, and storage of them strengthened in the process.
"Our results extend prior research by showing that external stimulation during sleep can influence a complex skill," says psychology professor Ken A Paller.
Participants were taught to play two artificially generated musical tunes with well-timed key presses. Then while the participants took a 90-minute nap, the researchers presented one of the tunes that had been practised, but not the other.
Using EEG to record the brain's electrical activity, the researchers made sure that the soft musical cues were presented during slow-wave sleep - a stage of sleep previously linked to cementing memories.
And, they found, participants made fewer errors with the melody that had been presented while they slept.
"We also found that electrophysiological signals during sleep correlated with the extent to which memory improved," says James Antony of the university's Interdepartmental Neuroscience Program. "These signals may thus be measuring the brain events that produce memory improvement during sleep."
Unfortunately, the research doesn't mean that it's possible to learn, say, a foreign language while asleep.
"The critical difference is that our research shows that memory is strengthened for something you've already learned," says associate psychology professor Paul Reber.
"Rather than learning something new in your sleep, we're talking about enhancing an existing memory by reactivating information recently acquired."
However, he says, the technique could perhaps aid more conventional learning.
"If you were learning how to speak in a foreign language during the day, for example, and then tried to reactivate those memories during sleep, perhaps you might enhance your learning," he says.