Steve Wozniak mentions this happening to him after a plane crash. Where he had a period where he didn't form permanent memories, and when that passed and he was able to, it was as if he awoke from a coma, even though he was functioning and interacting with people during this time. Think if the Memento (kinda based on a real case) guy suddenly regained the ability to hold memories, he would "awake" and to a period years later.
Perhaps something like this happened, where she was "around" and "interacting" but regained the ability to store memories and thus she "awoke".
