Lots of people seem to have significant "difficulties" with sleeping and waking, or at least a strong preference that demands willpower and tricks and habituation to steer away from. My body just doesn't really seem to care. If travel or work demands it, I can pretty easily get up at any time in the morning. Usually I enjoy it. I almost always wake up right away if I've set an alarm, and have little inclination to sn…
I used to came out with the same sories until travelling in Chile and Peru. There is a two hour time difference at some points of the year, even though they are on the same longitude. After a couple of days I didn't notice, and I realised it's just a number that you are becoming attached to.