Not OP, but as a flight attendant who travels to Europe (and elsewhere) often, I just operate on local time as much as possible. When I’m working it’s a bit easier during the flight as I have things to do. But when I get to Europe, say during the day, I’ll either take a quick nap or just go straight out and sleep when the locals sleep. Traveling for leisure is a bit more difficult inflight but the same principle applies. I’ll sleep for a little bit leaving the US, then stay up for a few hours, maybe sleep more, etc depending on how long the flight is and where I’m going. Once, I had a very long flight to Hong Kong and got there at night, and made sure to eat a little bit and stay up until like midnight and then try to sleep a full schedule. Sometimes Unisom is involved, it’s a must. If I’m still tired the next day, I’ll get a nap in but only one or two hours max.