I've figured out that I can pinpoint my general level of fatigue by pouring coffee in the morning. If it comes out of the coffee maker clear, or if it doesn't come out at all, I must be fried.
Making the coffee -- grinding the beans, putting them into the machine, pouring water in the reservoir, setting the start time -- is basically the last thing on the nightly chores list, the last thing I do before taking a shower and going to bed. And I screwed it up for three consecutive nights in mid-November. I forgot to grind the beans one time.