This is pretty much every day for me but it always seems worse when a) I have a bunch of other things I should be doing and b) when I’m in the middle of a really interesting book (in this case Outlander by Diana Gabaldon) and want to finish it (even though I have hundreds of pages left).
So even if I can’t read all day long, I will at least take a few breaks to keep my mind from wandering while I’m trying to concentrate on other important things, you know like my mid-term.