As long as you do work, breaks are good things
That's what I did for two years and managed to get the grades
I've read that taking a nap helps you retain information better. I can't find the original source, but it said something along the lines of: the recent information short term memory place in your brain fills up rather quickly and by taking a nap say 30mins or so that helps shift it to the long term memory bit and "empties" the recent info bit so you have more "space" for new information. (It was described in as simply as that, although they explained it a lot better than I did)
So basically taking a nap helps you revise! It's what got me through second year haha