Is grading bad for one's mental health?

Wednesday I spent days grading labs while students took a test. I did the same on Thursday. It was a different test and different labs, but the activity was the same. Today I graded the student "repairs" to Wednesday's test and a "10-13". Multiple choice questions that are based on the units we've covered so far. It's been a long slog. I believe deeply that students need to get back any tests, quizzes, or labs as quickly as possible for full effect - but a lot of this really gets to be painful. We (Charlie and I) watched a good movie on DVD tonight (State of Play) but I'm still wound up from grading. Better than boredom, I presume......