hi,
You can read her a story just before bedtime. Also make sure that she eats full dinner and that she plays with other kids in the evening. I think it is just a passing phase. At the same time do not be anxious yourself and try to relax.
hmmm... i don't believe in co-sleeping. what did you do to get your 5 year old to sleep on his own? i think that they get woken up by us adults tossing & turning in bed. is she tired during the day?