Interesting, i think my question popped up because i never really felt the effect of my environment on my circadian cycle.

So i wasn’t to much aware that people feel tired or the need to wake up at specific times of the day. I’m someone that can adapt like you said.

For me the only thing that i felt had an impact was if a specific hour is a habit. Then you feel way better sticking to it.

(That and of course the amount of sleep)