grading is bad for the teacher’s health

Talya [to advanced math students]: I have back your quadratic equations homework set…
Student 1: Whoa, you graded it already?!
Student 2: Didn’t we just give it to you? And the polynomials packet too?
Talya: Yes, but I had to get them back so that you could study for your test…
Students: But…you must be really sleep-deprived!
Student 3: Isn’t that bad for your health?