Crazy sleep patterns

I'm sooooo sick of having stupid, all-over-the-place sleep patterns. I've had insomnia for about a year - but not of the 'can't get to sleep' variety or even the 'get the sleep but wake up and can't get back to sleep' variety... mine has been the 'get to sleep, wake up 60 or 90 minutes later for five minutes or so, get back to sleep, wake up 60 or 90 minutes later for five minutes or so, rinse, repeat' variety. Basically I'm just getting into deep sleep then waking up again. And a few times there I had some nights of not getting to sleep at all until 4 or 5am but that didn't happen too often. Lately, however, it's been heaps better and I've been sleeping fairly normally. That is, until this weekend.... although it started so well! On Friday night I slept for about nine hours and it was great. Okay, I woke up a couple of times but I probably still had about 6 hours uninterrupted. Sadly, this obviously utterly confused my body because on Saturday night (Sunday morning) I didn't get to sleep until 3.30am. And last night it was about midnight but I woke up 4 times between midnight and 6.20am.

Therefore, I'm so tired today that I'm barely functioning. Yippee.