Have we found a solution? Last night I suggested to Matt that we put Waverly in our bed for the night. She always ends up there anyway. She typically wakes up and wanders around her room, before we realize she is awake. I thought all of that wandering may wake her up, making it more difficult to go back to sleep. It actually worked!! She woke up twice in the middle of the night, but we were get her to fall back asleep. She slept until 7!!
I am trying the same tactic tonight, hoping for similar results.