Hmmm, Waterhouse seems to have forgotten Mental Fatigue. When you're really pushing the brain neurons to fire for long periods, such as finding a logic error in a program (even worse: machine code), you can easily experience this malady. I think a few folks get this every so often while posting nodes on E2. If there's a particular word that would fit perfectly for your writeup, and you spend 45 minutes pushing words through your mental thesaurus until you find it, you can experience mental fatigue.

Some symptoms of mental fatigue include posting a random nodeshell rescue GTKY writeup in the midst of hypertechnical factuals, getting sudden almost painful cravings for coffee that has boiled off half of the water (and thus concentrating the life-giving caffeine), and sudden cranial explosions similar to the movie Scanners.