Interesting question.
In order to speak of insomnia, we need to know if these complaints affects her functioning during the day? I think it was really a good idea to suggest physical examination before starting cbt.
I suppose that you have asked for sleep hygiene?
Literature suggests that classical conditioning starts after about three weeks. That could be one reason: being awake in bed became a habit. Stimuluscontrol (or sleep deprivation) can be a help in that case
I"m really interested about further evolution of this case.
roland