Argh!
My sleep pattern is becoming even more erratic. I decided to have a quick nap (perhaps an hour and a half at most) at about a quarter past three yesterday afternoon, but have only just got up. I'm working the day shift today (and tomorrow), so I really hope that I don't fall asleep some time in the early afternoon as a consequence of getting up now - by rights, I should be asleep until five, but I'm far too awake to try to go back to sleep now...