Why, for this route
- Set your watch to Tokyo time at the gate and treat the cabin as destination time.
- When it is 08:00 in Tokyo, your body clock reads 19:00 — that gap is what the flight can start closing.
- Keep the cabin light on, move every couple of hours, and save caffeine for the first half of the flight.
- Expect about 8 days to adjust after landing (severe jet lag).