+1 It's amazing how easily I become depressed & frustrated and tear at myself mentally when I'm tired. I'm slowly, slowly learning to go to bed in those cases, and I do generally wake up much more optimistic. It's hard, though, because the fatigue feeds back on itself - I want to "punish" myself, so I stay up, say I'm not allowed to sleep yet, etc. So I keep feeling miserable, so I make myself miserable, etc. Cycle repeats.