One of my favourite authors, Sarah Vowell, wrote an essay on insomnia some years ago. I'm fond of that essay, partly because it is humourous. Now, partly because I can sympathize.
The question, of course, is, what should I do when I'm awake in the middle of the night? There are a multitude of things I could do with my time.
Sometimes I write. Or I knit. I read. Some times I have ended up doing the dishes and then tidying up the living room. The other night I organized the drawer-thing on my desk and emptied out a box of junk that needs sorting through (haven't finished sorting it yet). I thought about mounting my whiteboard on the wall, but activities involving nails and a hammer are usually best reserved for daytime hours.
I'm considering crawling into bed for now, in the hopes that I'll actually fall asleep. If I can't though, I might find myself cleaning the bathroom at 3 in the morning. We shall see.