When I first started back to playing and singing I noticed how hard it was to properly focus my eyes to follow the notes. My concentration would lapse and I would fall behind. As I kept on, over time things got better. Still, getting the words in to a fast moving song requires practice and concentration. Concentrating intently is very tiring. Rehearsals and painting sessions often exhaust me. Following media or reading posts on line cause dizziness and nausea for me and must take on line time in short bits or I literally lurch and weave away from my device. Reading newspapers brings on same ....I think because of moving my eyes up and down and back and forth on the page. Books do not cause dizziness most often because one's head stays stable,