Not to be all gloom and doom, but we had over a year of this. Started at around the 12 month mark and we are only starting to see some improvements now. I tried everything under the sun, from going to bed earlier, to going to bed later, to laying on the floor in his room, to bringing him into bed with us etc etc... None of it worked. Until one day about a month ago when he slept to 6.30am completely out of the blue (the best we'd had in the year beforehand was 5.45am). Since then we've gradually been getting more and more 6am or laters...

I think some toddlers just do this for some unknown reason. There are heaps of threads on here from others who've been through the same thing and I know one of my nieces went through a similar thing which gradually changed after she turned two.

Sorry to be so depressing, just my experience. Hopefully yours is very, very different