Yes, what's up with this staying up nonsense.
Either the day has been too awesome to end - OR it's been too sucky or boring and I don't want to go to bed with that. A boring end to a boring day is a big spot of meh on your mood. Going to bed sad makes it hard to sleep because it WILL be on your mind and not leave you alone just because you're exhausted.
I've had a decent day, but I've not left the house, and I've worn my pyjama-shirt and my hair is dirty. With that, I don't particularly feel like I had a day at all, even if some nice things went on between my two desks and computers. So I feel the need to stay up and entertain the hell out of myself until going to bed and ponder things until sleep takes over seem like a more attractive activity.
So that's what I'll be doing now.