A dreamland ditty played softly during a nap helps people hit the right notes while awake. Soft tones during sleep creep into the napping brain and strengthen playing skills, researchers report online June 24 in Nature Neuroscience.
The results don’t mean that after a nighttime Beethoven sonata, a piano novice will wake up with the ability to play it. But the results do suggest that an existing skill can be sharpened during a nap, says study coauthor Ken Paller of Northwestern University in Evanston, Ill.
Earlier work by Paller and others has found that sound and odor cues during sleep can improve a person’s memory for the locations of objects. The new study extends those results by showing that a learned skill — in this instance, playing music — can also be influenced during sleep. Although these sorts of experiments are just getting started, “the door is wide open,” Paller says. Musical ability, athletic prowess and other talents that normally require a lot of practice may be amenable to boosts during sleep.
Before the easy job of having a nap, 16 right-handed participants in the study had to do some actual work. Volunteers learned two different not-very-catchy tunes, played with their left hands on the a, s, d and f keys of a computer. In an arrangement similar to that of Guitar Hero, circles that floated up the screen told participants which key to hit and when.
After this training, the volunteers’ chairs were converted into comfy beds for a 90-minute nap. When scalp electrodes indicated that the snoozers had entered slow-wave sleep, a phase that’s thought to be important for memory processing, researchers surreptitiously played one of the two songs the volunteers had just learned.
Refreshed from their siestas, volunteers were better overall at playing both songs than before their naps. But there was an important difference in this improvement: People were better at playing the song that was broadcasted during their nap than the song that hadn’t graced their sleep.
This effect may be caused in part by sleep spindles, waves of electrical activity that have been linked to memory processing during sleep. Spindles in the right premotor cortex — the brain area that controls movement of the left hand — were tied with the post-nap performance, the team found. “The more spindles, the more benefit,” Paller says.
It’s not clear whether the gain represents a simple boost or just a bias in shifting the brain’s attention to one song at the expense of the other, Paller says. Sleep may offer a finite window of improvement, such that enhancing one skill may come at the expense of another.
Just because a skill can be sharpened during sleep doesn’t necessarily mean that it should, says sleep researcher Robert Stickgold of Harvard Medical School. “I think your brain does a lot of triaging at night. Now, you’re trying to override that triaging and tell your brain what it should be worrying about.”
And overriding the brain is fraught with the problem of choosing what to listen to, Stickgold says. “I would argue that sleep might be smarter than you.”