What occurs when you overwork yourself into a state of limited mental acuity, depleted emotions, and strength completely drained from your body.
I was so burned out I didn't even know I was burned out. When three days of vacation helped maybe 2%, I realized I had to cut way, way back on the hours. I don't mind playing brinksmanship with myself, screwing around until deadline on shit I have to do. But, when I miss even those basic deadlines and my important stuff just starts piling up - of what I can't even function enough to take care of - well, it was pathetic, and I'm only just now coming out of it after chilling a few weeks.