the.com/jet lag
your body wakes up in a country its brain hasn't landed in yet.
means the fatigue and disorientation caused by crossing time zones faster than your internal clock can reset.
from coined in the 1960s once commercial jets made crossing multiple time zones in hours possible; before planes, travel was slow enough that bodies adjusted en route.
circadian mismatchsuprachiasmatic nucleus still runs on old timezone
direction biasflying east is harder than flying west
recovery rateroughly one day per time zone crossed
light fixsunlight exposure resets the clock fastest