Unsettling Insomnia

I'm rarely awake at one o'clock in the morning when I have been in all evening - especially since I had a busy and tiring weekend and at around eight this evening could have happily gone to bed and stayed there until morning. In truth, I don't actually know why I'm awake, let alone up and typing. I was happily reading my book in bed and just before midnight I put it down and turned off the light to go to sleep, and was then struck by an immense feeling of...something. A worry, a bad feeling, an ominous, strange sense that something was wrong. It has still not fully escaped me, though I have found no reason for it thus far. Still, I now cannot sleep for this odd kind of worry about something intangible that is gripping me. So here I am. Logically, I'm sure it is nothing, there is nothing more untoward in the world than there is any other night, but I can't shake it. And i so want to sleep, I'm exhausted and have a busy week to come, filled with end-of-uni lessons and japes (read: drinking) and Christmas present buying and traveling home for the Christmas holiday, and one night of sleep lost is not going to be made up, but will be sorely missed.
I read somewhere that the best thing to do when insomnia hits (I assume this counts as insomnia, I don't know if there's a word for random wariness in the night) is to get up and do something gentle and not too stimulating to calm you and get you into the mood of sleep. This writing appears to be helping actually, the fear, or whatever it was, is dissipating and tiredness is taking over my eyelids and body, and I think soon I will be able to surrender to that welcome mistress of sleep. It also seems the more tired I get, the more poetic! Perhaps when I read this back tomorrow it won't seem that way - it will probably be clear just how tired I am, I realise I'm beginning to ramble somewhat. I think now may be the time to attempt sleep once more. See you on the other side.