L.J.
If you don't have already have one, buy her a new pretty night light or really dim lamp for the bedroom. This might help her to be able to see everything is still the same as before time to go to sleep and if she wakes up, she'll see she's fine. Maybe a good new snuggle toy would help to feel relaxed too. It's probably just the new environment making her uneasy. Have a visit or two to the daycare before going for a full day so she knows the teacher's face and name and hopefully a friend or two by name.