When I've stayed at meditation retreats, away from tv/computer screens and most artificial light, it feels normal to fall asleep at 8 or 9 pm, and getting up early isn't a problem. When I'm back in the normal western electronic world I do often stay up much later, but I usually wake up before my alarm goes off. I often set it to go off just early enough to help keep me from being late, but have ample time to naturally wake up. Even when I set it for earlier times, as I often do now, it's normal to wake up a few seconds before the alarm starts going off
I wonder if programming yourself to wake up early without an alarm clock going off still counts as free running sleep.