I am very good at just staying up late to adjust to a timezone. I can do this fairly reliably. Going to the US and Europe can be done by this method (rather well). Coming back is another story though. Going to sleep at an earlier time (for me) doesn’t come easy. Grr…
Going onto nightshift only ever takes me a day or two, or sometimes no effort at all.
But coming off takes a week. If only I could force myself to go to bed 8 hours later, then 8 hours later again.
Melatonin is the answer though you need to get it in an Asian country I believe (Not available in USA or OZ (I think). It is basiciall an internal clock reset tablet.
You take them at the time you would typicially need to go to bed once at your destination ie if you are heading to the USA, at 10pm once you land in the USA you take the tablets, they help realign the body quickly and the third day tiredness doesn’t hit nearly as badly. Spending time in the sun is also good, though do not do this after a long haul flight as you will sunburn very quickly