In the Zone (work, not proximal development)

Why is it that I always get "in the zone" late at night? I hate that I am a night owl, yet I chose a profession that requires me to be up at the crack of dawn. I guess I will just have to retrain my body to get to bed earlier. The problem is that I come home and start working and it just gets my brain going. I begin to cross items of my to do list and before I know it the clock says 11:00PM. What's a girl to do? Tips, please.