Do not drink a mug of strong coffee at 9pm, in an attempt to fend off sleep long enough to get some Xmas cards written and some paperwork completed (and a blog post published!). Result: it's half past midnight and I am wide awake. I don't suffer from insomnia generally. I'm used to getting my sleep! As soon as I realise I'm not going to get at least 7 hours sleep, I start to panic. And sleep recedes further.
I wonder if cocoa would be an antidote? Or a large brandy?