Sleep sleep, where art thou sleep

I'm at my wits end. No matter when A goes to bed, or how well or poorly she naps or sleeps during the night, she is up at somewhere between 5 and 5:20 am. This is not an hour at which I function. At all. But given the option between trying to force the issue and therefore waking up C who REALLY doesn't function well on less than 12 hours of sleep a night, I am stuck waking up at 5 am. Is it really true that there are 20 month olds who can function on eight hours a night? Cause that's what I'm looking at today. She got eight hours. And that's not counting the time spent during the middle of the night wake ups. I would take 7. Even 6:30. I was happy at 6:30. I used to go to work at 6:30. 6:30 would work.

Someone please tell me this is a phase and how you got through it. Please. I beg of you.