Scientists have known for years that sleep is crucial to learning and memory.

Scientists have known for years that sleep is crucial to learning and memory. But exactly how that information consolidates during shut-eye has remained a mystery--until now. Researchers at Brown University found that brain waves in an area of the brain called the supplementary motor area (pictured, yellow) that occurred during sleep were associated with better learning of a motor task. The researchers asked a group of students to learn a series of finger-taps, not unlike the motions performed by pianists the world over. For three nights, the subjects slept as usual while their brain waves were recorded. On the fourth day, the subjects were asked to learn the task with their non-dominant hand, and half were allowed to sleep for three hours afterwards. Those who had slept performed better. Brain scans showed that the brainwaves the researchers had observed on the EEG were located in the supplementary motor area. The results further emphasize that sleep is actually very crucial to learning and normal functioning, and isn't just the brain "resting."

Source: http://news.brown.edu/pressreleases/2013/08/sleep