Yeah... There was no "reading" in our ancestral environment, it's rather unnatural for a human brain to focus on the page where nothing happens. Some people can adapt to that, other people need stimulation of some kind.

And it's not like some ADHD thing which is new. E.g. Stanisław Lem as a kid: "But because the act of reading was too passive, too simple, I would rest a chair leg on my calf or knee or foot and with little movements keep the chair at the very brink of falling."