For years I went to bed at 9:30 and was asleep by 10 and got up early. Nowadays I might not go to bed until like 3am and yet I'll still get up early and then wonder why I'm tired.
On a "good sleep night" I'll get to sleep about 11 or midnight and be up at 7. On a "bad sleep night" (like tonight) I'll wake up in the early hours and not get back to sleep.