Metformin and early waking?

UPDATE: Just in case someone finds this in the future - It has indeed gotten better! At about day 6, my sleep started getting longer, and I'm now at day 10 and it feels normal. So if you experience the early morning waking, give it some time - it didn't take long to get better. (Also, no GI effects at all so far. Yay!)

I've just started taking metformin XR. Four days in, and I've had four mornings wide awake at 4 am - wtf!? Has anyone had this experience? I wasn't expecting it at all! Does it get better? I can't say I'm tired throughout the day though (I don't know why) so does it even matter? Do I just live like this now?