....i'm pretty sure now that it was the sleep aid, Lunesta, that I'd taken excessively last week, causing the fuzziness. That really should've been my first guess. Although on the list of possible side effects, "anxiety and depression" rank far below "liver failure," so I wasn't really anticipating it.
...I have found lately that eating peanuts before bed helps put me to sleep without calamity. Peanuts, like turkey, are apparently a natural source of tryptophan, which I believe is spelled like that.