For some reason my brain associates even the tiniest amount of daylight with morning. This is why I have been awake around 5 o'clock every morning for the last few weeks. While I am an early starter (by 9 p.m I tend to be fading fast - if watching TV you can find me drifting off in front of Midsomer Murders, though maybe that says more about my viewing habits than anything else), this is far earlier than I really want to be up.
I've tried eye masks - very claustrophobic and I have a tendency to fling them off in my sleep which makes it pointless wearing them. I've tried sleeping with the duvet over my head, which is far too hot. The only other thing I can think of trying is black out blinds - but as I am moving flats soon, it seems a bit pointless to do something for a month or so and then have to do it again.
In the meantime I shall just attempt to not fall asleep on my keyboard...zzz