The night before a big test in high school, I used to sleep with my notes under my pillow. The rationale was that doing so would give the test material a chance to seep up through the pillow into my brain.
I knew that OF COURSE that wasn’t true. OF COURSE you can't learn through osmosis! But, nonetheless, I really believed that after all my studying I could give myself an extra boost by sleeping on top of my papers. I loved imagining the words and concepts drifting upwards off the page throughout the night and embedding themselves into my subconscious mind.
Without fail, the next morning I always felt that it had worked and I knew the test material a little better than I had when I had gone to bed the night before.
Looking back now, I believe that I was relying on my subconscious to keep processing the material while I slept.
Sleep is a powerful tool in learning. While you sleep, your brain is busy processing and consolidating the information you learned during the day. I find that sleep becomes especially important when I am trying to learn things quickly or learn a lot of new material.
I have been finding while working on these Beethoven violin sonatas, some of which are very new to me, that if I practice something and then don’t come back to it for a few days (because I’m busy practicing all the other things), somehow a lot of the difficult “spots” have cleared themselves up, even without daily practice.
I don't even have to sleep with the music under my pillow!
