Imagine climbing into
bed, turning off the light, and shutting your eyes. As you drift off to sleep, a small machine
monitors your brainwaves, and when it indicates that you have entered a stage
of deep rest known as slow-wave sleep, a Mozart sonata begins to play
softly. You’ve spent a solid hour
practicing this sonata during the day, and while it plays repeatedly during
your slumber, the memory trace laid down in your brain during that practice
session becomes reactivated in both the auditory and motor parts of the brain. In the morning, unaware of your nighttime
“practice session”, your performance of the sonata is significantly improved.
I would normally be highly skeptical of this type of
claim. It reminds me of that scene in
Huxley’s Brave New World where
children listen to history lessons in their sleep, instead of having to go to
school. It sounds like new age
mumbo-jumbo to me.
Except that this exact type of learning effect has been shown by researchers at Northwestern University and published in this month’s issue of Nature Neuroscience. The experiment was
straightforward: Sixteen people learned
to play two short melodies on the piano, and then had a 90 minute nap. When they entered slow-wave sleep, one of the
melodies was quietly played twenty times.
After the nap, performance on the melody that had been played during the
nap was significantly improved compared to the melody that wasn’t played.
This study brings together two interesting aspects of music
learning. The first is the role of sleep
in aiding learning. Previous studies
have shown that memory consolidation during sleep is an important source of improvement between practice sessions. The second aspect is the importance of
sensorimotor integration in learning to play an instrument. During practicing, our brains learn to associate the sounds we produce (the auditory feedback) with the movements that lead to those sounds. The auditory and motor parts of our brains become more highly linked, so that
just hearing a song that we know how to play activates motor parts of the brain, and just making the movements associated with playing a song
(like pressing the keys of an unplugged keyboard) causes auditory parts of the
brain to light up. This is why hearing
the music in our sleep can cause improvements in our motor performance: the replaying of the song reactivates the
auditory memory, which simultaneously reactivates the motor memory,
strengthening both these memories and their association with each other.
So, am I going to start listening to piano music in my
sleep? I’m certainly considering giving
it a try. There are a few possible
caveats to the potential gains here.
First, music might interfere with sleep.
In the research study, there were a couple of subjects who did wake up
while the music was playing, so this could definitely be a downside. Another issue to consider is that the music
should probably be played during slow-wave sleep, as it was in the research
study, to have maximum effect (although the effects of playing music during
other stages of sleep have yet to be examined).
Most people (myself included) don’t keep track of when they are in deep
sleep. However, there are iphone apps
that claim to monitor stages of sleep (usually these aim to waken you during
light sleep) and these could potentially be adapted to trigger music during
deep sleep. A third issue is that the
effect on music motor learning might simply be a bias instead of an absolute
gain in learning. What this means is
that listening to one song might improve performance on that song at the
expense of other songs being learned. In
the research study, the melody that was played during sleep improved 7.9%,
while the other melody only improved 2.6%.
Meanwhile, for people who didn’t have either melody played during their
sleep, both melodies improved about 4.4%.
Perhaps there is a limit to how much improvement can happen during
sleep: listening to the one melody caused it to be improved but maybe also
caused the other melody to improve less.
In any case, it sounds like a fun summer project and I do
have a couple of piano pieces I’m trying to learn, so why not? Sweet dreams!
Reference:
Antony, J.W.,
Gobel, E.W., O’Hare, J.K., Reber, P.J., and Paller, K.A. (2012). Cued memory
reactivation during sleep influences skill learning. Nature Neuroscience 15,
1114–1116.
