Well, after spending most of yesterday afternoon asleep I felt marginally better, though still by no means up to partying. Gareth invited me round to play a board game at the Gallery instead, which was just about my speed provided it wasn't too complex and intelligent a game (and despite this I still made clear errors and played badly…), and about nine hours' sleep last night leaves me feeling plausibly human once more. Though I think for at least this weekend, and possibly next as well, I should relax, do very little, and in particular resist the temptation to continue with the next phase of my PuTTY development master plan, because no matter how much my brain is thrumming with ideas and enthusiasm for the task I really don't want to find myself collapsing like that again in the near future. :-(
People need to lie fallow every so often (as opposed to sleep, which they need to do every day. Oops). There's no magic pill you can take to recharge yourself emotionally or creativity-wise. Though one will be invented one day, and it will have unpleasant side-effects of its own....