I've spent much of the day avoiding starting the rewrites on the novel's first draft. Thankfully, it's not procrastination. I'm just trying to leave it a little while to come at it with fresh eyes. Finding myself with this draft finished, I've suddenly found a lot of energy for the PhD thesis. It's not so much that I was distracted from it by the fiction, because I felt stuck on it before I started; it's more that concentrating on something else for a short while has renewed my commitment to it.
One stupid thing that's helped is putting the thesis in double line spacing. It's something that most editors require for everything else, and as a result I'm now in the habit. Because it's easier to read, it doesn't feel so much like a dense, headache inducing mass anymore.