We had/have the same experience with DD and missing 'her window'. Guess what? The window must be sealed shut because she always has full energy when she goes to bed, unless she is sick. I learned early on that this is just DD but she accepted bed time and though full of energy would go to bed with no problems. We would hear her upstairs talking to her animals for a while before she did finally give in to sleep but I think she really needed quiet time before getting to that point.