A proper doctoral student does not even notice that it is spring break. If you think this is unlikely, or that the link is funny, well, one of our professors told us that he did that himself once.
Students who aren't quite that good are expected to stick around, at least, and work on research and classwork. Small dispensations may be granted to visit family or to have that open-heart surgery you've been postponing. You may under no circumstances travel to Florida or Tahiti. One is allowed to avoid coming in to campus or to admit to sleeping in.
Given this, I do not write to you from a sunny clime - although the sun was out today, it was in the 40s here in Nashville. I have slacked a little bit. Yesterday, I went to the Vandy men's basketball game, tickets courtesy of my advisor, which was good except for the bit where we lost. And today I took a good chunk of time to go to Espey Cave with some grotto folks.
All this, of course, only amounts to "study breaks" between classwork.