night weaning -- a big headache!!

Hello,

My daugther is 11 months old and i nurse her every 2-3 hours during
the day . Until 9 months she was able to sleep for atleast 3
consecutive hours in the night, before waking up for feeds. But
surprisingly now, when she is growing bigger, she wakes up 1 to 2
hours in the night for me to nurse... And once i put her down after
nursing she keeps rolling left to right as though she is not able to
find a comfortable position to sleep. My sleep is completely disturbed
as i end up waking very often in the night. I am not able to
understand the change in behaviour after 9 months.... she was fine
until then.... One thing i make very sure is that she isnt hungry
before she goes to bed... She has her solids, and then my milk....
Even when she wakes up in the night, i feel that it is only for
comfort and not for milk.... I want to be able to sleep atleast 3-4
hours straight but the situation keeps worsening...

Can somebody throw light on what could be the problem? I live in
Phoenix, AZ and it doesnt even get that cold in the night for her to
feel that uncomfortable. Infact it sometimes gets warm in the room and
i get to turn the AC on....

Can you also provide tips on how to wean her during the night?

Thanks!
Aruna.