Eastbound is worse for me. When I went straight through, recently, London to Sydney, I was wiped out for 2 days. Coming back was better. This was business class, but even so. However when I was working I used to fly to Tokyo. Arrive Saturday pm. Get up following morning, at 7 am, to be taken to play golf. Golf and polite chat all day, back to hotel 7pm! Following morning, Monday start work at 9am! Hardly noticed jet lag. What I think those showed was the power of the mind and adrenalin. As it was work, and you had to concentrate, somehow jetlag didn't get a look in. My Sydney trip was after I retired!