My situation is two parents working and two younger kids. The element of rising early that actually energizes me is control. It is one of the few things I can unilaterally do to shift productive time. The rest of my day is the fragmented or constrained, and my mental energy at the end is very low. I like the feeling of be able to decide that some random afternoon meeting gets me at 50% power, and items of my choosing get my full attention at 5am.