I woke about 1:20 to the sound of Deborah leaving, then couldn't get back to sleep. I think hunger was the problem, so I got up to eat, digest, read... No sleepyness returning... I've since watched another chapter of CSS for Designers, failed to fix my video library after upgrading from Democracy Player to Miro, and ineffectually reviewed my notes for a project I'm on. Still no sign of sleep. I guess reading at the computer is not a good sleep tactic, and in future I should read in bed.
Deborah returned around 2:30 and went to bed. I figured I should follow suit, so I dragged myself to bed, but no go: it was like my body believed it had to stay awake and was working off nervous energy.
I'm up again now, but only long enough to digest some warm milk. Time to look for the herbal relaxant tablets that a few people have been praising...