Last Monday was a "fall break" day off for me--my institution doesn't have a full week of fall break. That one disruption totally threw me off the weekly routine; I kept staying up too late during the long weekend, and so spent last week feeling groggy, out of sync, and vaguely cross. And I got very little done. I think I've finally reset to normal.
Sometimes a break comes at just the right time, and for me this one seems to have come at the wrong time.