It sounds like a bizarre problem, but even though my baby has started to do a sterling job of sleeping through the night, for the past four nights, I have woken at about 4am and not been able to get back to sleep again. It's seriously annoying. It's as though my body clock has decided it's time to get up, even though I feel knackered all through the day. Has anyone else had this problem? I lie for hours wondering whether to get up or just lie awake.