Riddle Me This

How does less napping during the day equal needing to sleep less during the night? She normally doesn't wake up until 7:45 or 8:00, but this morning she was wide awake at 6:30. I don't think I have any chance of keeping her awake until after lunch today to keep up with the one nap experiment. She's already getting the sleepy eyes and it is only 9:00 am. I knew this one nap transition was too good to be true.