Hello,
well it's all in the title. 15 mo DD was never a very good sleeper at night, still BFing at night now, but it was "only" 3 times at worst... until we moved overseas.
We stayed with my dad for a month and her sleep routine was all over the place, due to everyone's conflicting schedules, and DD went to bed much much later than usual - around 10pm instead of 8pm. 
And she started demanding the breast every single time she wakes up, sometimes every hour, and co-slept with me from midnight - in other words I am totally shattered.
I was intending to slowly stop BFing naturally, massive fail! 
Now we have moved to our own place and started our good old earlier routine again, but it's not working.
I suppose DD is totally confused with all these changes, surroundings, people, houses, bedrooms, etc etc... I would most welcome any experience on the topic, and how long it took you to re-arrange your LO's sleep patterns...
THANKS!!!