Soft tones during sleep creep into the napping brain and strengthen playing skills, researchers report online June 24 in Nature Neuroscience. 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. 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.