But anyone who has flown between the East Coast and West Coast of the US knows that the sun doesn't determine when you feel tired or when you wake up: your sleep hygiene does.
I used to fly to SF from Boston and wanted to go to bed at 7-8pm every night and then would wake up at 4am. Not because of sunlight but because my body was used to that schedule.
I find the 3 hour difference to the west coast to be way harder to adjust to than the 5 or 6 hour (depending on destination) difference to Europe. I'm a zombie for a week going to California and spring right back to eastern time going home.
Going to Europe, it's about a day to fully kick over to the time change in either direction. Admittedly, it's a rough day headed east that usually involves an afternoon nap, but I've come to despise the three hour change to Pacific time far more.
But if I take a short trip from the East Coast to the West Coast in the US, I often go to bed on the early side and wake up early.
> Researchers said the wavelengths at sunrise and sunset have the biggest impact to brain centers that regulate our circadian clock and our mood and alertness.
https://www.sciencedaily.com/releases/2020/02/200220141731.h...