I regularly go to sleep at around 6 am, when the sun starts coming up, and wake up at around 2 / 3 pm. It doesn't matter where I am, or the time of the year. That's my natural bed time.
6am is a whole new ball game. Not sure how I could deal with that.
[1] https://en.wikipedia.org/wiki/Delayed_sleep_phase_disorder
It's the family bit that's hell, with a partner who lives on almost a perfect 06:00 - 22:00 schedule and can adjust that to waking earlier if needed, and now kids who also don't like to sleep past 07:00. I'm now stuck in a limbo of family forcing me to get up early, and all my body and mind and soul making me stay up late. A tug of war that's been going on for years now.