I've done this before too. In high school track, I competed in several jumps and sprints. I really loved triple jump, but didn't have time to practice it regularly. My triple jump PR had been pretty consistent for a while, slowly improving by about 2 feet over my junior and senior year.
The week before my last District track meet as a senior, I was worried about my triple jump because I hadn't gotten a chance to practice it for several weeks. I thought about it all week long, even had a dream about what it would feel like jumping. At the meet that week, I hit a new PR by three feet! That beat all the progress of the previous 2+ years in one meet. I just hit all the technique of each phase better than I ever had. It felt exactly like I'd thought about it.
I've been a firm believer in visualization since then. OK, back to work and visualizing myself sleeping. I'm going to sleep like a champion tonight.