Whenever I'm doing something visually stimulating for a while before bed, it ends up going in my head while I'm in the process of falling asleep. Tetris, MarioKart, any puzzle game involving moving pieces. Sometimes if I look at a lot of .gifs (really short animations) I get semi-dreams in the form of a lot of little clips. This is all especially weird because most of my waking thoughts are verbal, but my dreams are nearly all visual.