The thing that kills me is when this situation occurs:

1. You actually get a good night's sleep. Planned block out time 0830 local.
2. Flight delays for some reason such as loading/maintenance for 4 hours thus exceeding duty day.
3. Scheduling says "no problem" go back to the hotel for min rest, and we'll see ya again in another 12 hours.
4. Start nightmare all over again, now that you are 180* out of cycle, and fly 15 hours, land for 3 hours, take off again for another 2 hours, land, go to hotel, min rest again, fly 15 hours.

There needs to be some kind of factor for the time zones crossed. We need a scientifically backed formula.

I don't wish long haul on my worst enemy. It can be brutal. They don't pay me enough for this.....