Monday, March 4, 2013

The value of a nap during skill learning

There are lots of skills that we pick up over the years.  Driving requires a complex coordination of hands and feet to control a car.  Playing a musical instrument involves learning many different movements to produce beautiful sounds. 

When we first learn these skills, we often spend a lot of time practicing.  I play the saxophone, and when I’m learning something new, I will repeat a pattern many times on the horn.  As I go over that pattern, it gets a little better.

As it turns out, though, after I’m done practicing, I’m not done learning.  My skill will actually continue to improve once I go to sleep.  For example, Sara Mednick and William Alaynick review a number of findings from the sleep literature in a 2010 review paper in the Journal of Experimental Clinical Medicine.  They point to findings showing that after people practice tapping a rhythmic pattern, they get a little better at it.  After they sleep for the night and wake up, their performance on that pattern is even better than it was before they slept.  Not only that, but even a nap can help.  Studies show that if you nap for an hour or so, you’ll also improve on a skill you’re learning.

What’s going on here?

There are five stages of sleep that are distinguished by brain activity and chemical changes in the brain.  The first stage lasts a couple of minutes when you first fall asleep.  The second stage of sleep (cleverly called Stage 2 sleep) is the kind of sleep that occupies about 60% of your night.  Stages 3 and 4 of sleep are sometimes called Slow Wave Sleep because of a characteristic pattern of electrical activity that they create.  The last stage is REM sleep, which is named for the rapid eye movements people make in that stage.  A number of studies demonstrate that skill learning is related to getting Stage 2 sleep. 

Finally, an interesting paper by Ursula Debarnot, Eleonora Castellani, Gaetano Valenza, Laura Sebastiani, and Aymeric Guillot in the December, 2011 issue of Cognitive, Affective, and Behavioral Neuroscience brings all of this together along with an interesting practice procedure.  In their study, participants (none of whom were musicians) first practiced some simple tapping patterns a couple of times.  Then, rather than practicing tapping, they just practiced mentally by thinking about tapping the pattern rather than doing it for real.  There is some evidence suggesting that this mental practice can improve your performance on a real skill.

After that, some people stayed awake while others took a nap.  Those who took a nap slept for either 10 minutes or an hour. 

People did get better at the skill by practicing mentally.  As with other skills, taking a nap increased the amount of improvement.  The fascinating ting about this study was that even a 10-minute nap helped to improve tapping performance.

Most of us spend about a third of our lives asleep.  That means that by the time you are 30 years old, you have slept for about 10 years.  It is nice to know that this sleep is having a positive influence on your ability to learn.