You're boring yourself too much. Don't let it feel like work when you're studying anatomy and stuff like that. Keep yourself entertained with some cool speed painting video playing in a small window at the side of the screen.
When you have the flow of entertainment happening, you don't feel any migraines, or you just don't care about it at all because you're having such a good time learning about mysterious stuff in art that you didn't understand earlier.
I might be wrong though, maybe you're focusing too much on the computer screen and need to go chillax for just a few minutes, looking in the distance.