Took yesterday afternoon off from work. I'm putting it down as sick time, because I'm still not feeling well and I'd run out of energy and all ability to concentrate, but if I'm being completely honest I mostly left because I realized I was crazy. Like, "I have no sense of perspective, everything is massively irritating, and I have lost all ability to conceal my frustration or respond in a patient, measured, and proportionate manner." Basically, what tipped the balance wasn't so much exhaustion as the realization that if I stayed at work, something was going to set me off and I was going to blow up at someone -- anyone -- in a hugely unprofessional manner.
It's still better than Sunday. Sunday was miserable. But I'm not bouncing back anywhere near as fast as I'd like to be doing.