I then proceeded to spend most of the ensuing eighteen hours asleep -- about half of them in front of the laptop downstairs on the sofa, and then in bed. I've been dozing on-and-off since I got up, too.
I suspect this is part of the cold I started on Monday. Or just post-convention knackeredness, or some of each.
I'm not going to the BSFA pub meeting tonight, then. Enjoy it, those who are.