Yesterday I heard a song for the first time, despite it being about 30 years old. The song was Hummingbird by Seals and Crofts. I went out and bought the CD and proceeded to listen to that song continuously over the next several hours. (I know that sounds crazy, and much of the song is kind of silly, but the transition part from 2:00 to 2:50 was so beautiful I couldn't get enough of it.) I ended up falling asleep with the headphones on and the song continually repeating. When I woke up this morning, I decided to play my new-found song a few more times. But something mysterious happened -- it sounded slightly different than it did the night before. I can't put my finger on the difference. The harmonies or chords sounded a bit off. After a few plays, however, it was back to "normal." I've noticed this with other songs (not necessarily new ones) that I play over and over at night. They sound a little different in the morning. Is my brain doing some kind of processing on the song at night? Am I actually hearing the song while I'm sleeping? I know this whole thing sounds strange; I hope someone else has experienced it.