"Boffinry"?
Never mind that; back in college, during the Late Mesozoic (late 1970s) I was able to easily reset my "internal clock" with small judiciously-applied doses of LSD. No, really.
But, seriously...
Most of my air travel these days is to and from the West Coast of Mexico, once a year, during which I cross a grand total of one time zone, so no chance of serious jet lag.
However, the wife and I have just recently returned from two weeks in South Africa -- approximately 18 hours' flight each way between Johannesburg and Washington, DC. Going there wasn't too tough to deal with (aside from the ordeal of 18 hours flying over water), but coming back was a whole different story. Left Jo'burg in late-ish afternoon Friday, arrived Washington DC shortly before sunrise Saturday, having had only three hours' sleep -- and really piss-poor quality sleep at that. My waking state on arrival home was about what it usually is when I've had to be up at 5:30 or 6am EDT, and I made it through to mid-afternoon OK, but around 4pm, it was like hitting a wall. I desperately craved a good nap, but I knew I wouldn't be able to go to bed at my normal time (around 2am), so I made a pot of coffee and slogged through the rest of the day and evening.
Problem is, the wife and I have found ourselves snapping wide awake, bright-eyed and bushy-tailed, at around 4:30am every morning since Saturday (when we arrived home), so there we were having our regular coffee and morning news and feeding the cat at 5am (poor confused kitty). Our sleep patterns are still a bit distorted nearly a week after flying home, though we're waking at slightly more normal hours (6:30 or 7am). However, I'm still nodding at around 7pm. We sure could've used some of that sleep-pattern "boffinry" then (or, in my case, a quarter blotter of American Beauty).
It doesn't help that I already keep what a friend of mine calls "hacker's hours", so flying east for eighteen hours from Jo'burg to DC hasn't helped things any.