When do you get up in the morning daily?

I usually get up at 6:15 AM. I generally sleep late. And if I sleep later than the usual time, even then I would get up at the usual time, i.e., 6:15 AM. But, if I sleep early some day by say, two hours, I have a tendency to get up earlier than the usual time by almost two hours. I can never sleep during day time.