London to Tokyo advances your body clock by eight to nine hours – a large eastward shift, the hardest kind. Most travellers feel strongly jet-lagged for around eight days. Because you must sleep and wake much earlier than your body wants, a few nights of earlier bedtimes before you fly and bright morning light in Tokyo matter most.
London to Tokyo at a glance
| Time difference | Tokyo is about 8 hours ahead of London in summer, 9 hours in winter (Japan has no daylight saving) |
|---|---|
| Direction | Eastward – your clock advances (the hardest direction) |
| Time zones crossed | About 8-9 |
| Jet lag estimate | Roughly 7-8 out of 10 (high) |
| Body clock on arrival | You land in the morning; your body reads the middle of the night |
| Adaptation | Around 8 days |
| Flight time | About 11.5-12 hours |
These figures are transparent estimates, not clinically validated. The exact time difference depends on the date; the calculator resolves it for your trip.
Time difference and direction
Tokyo is eight hours ahead of London in the European summer and nine hours ahead in winter, because the UK uses daylight saving and Japan does not. You travel east, so your clock must advance – the hardest adjustment – and the shift is large, which is why this ranks among the tougher long-hauls. See why does jet lag happen for the mechanism, and compare the very similar Frankfurt to Tokyo.
Jet lag estimate and body clock
Expect a high jet lag, around seven to eight out of ten. Flights typically leave London around lunchtime and arrive in Tokyo the next morning, but your body clock is deep in its night, so the first local day is hard. The eastward signature is trouble sleeping at the Tokyo bedtime and fogginess in the Tokyo morning until your clock advances.
Adaptation: how long it lasts
Plan for about eight days. An eight-to-nine-hour eastward shift is near the upper end of everyday jet lag, and the clock advances only around an hour a day. Bright morning light in Tokyo is the strongest tool; mistimed light can stall you, so lean on the light exposure planner.
Before the flight
Preparation matters here. For three nights before departure, go to bed and wake an hour earlier each night – up to a couple of hours total – and get bright light early. You will not fully pre-adapt to nine hours, but every hour you shift at home is an hour you do not have to fight in Tokyo.
During the flight
Set your watch to Tokyo time on boarding and sleep during the stretch that overlaps Tokyo’s night, staying awake as it turns to daytime there. Hydrate, avoid alcohol, and use the flight sleep calculator to see exactly when to rest.
After arrival
Get bright morning and midday light on your first full day to advance your clock, and avoid bright light late in the evening. Do not nap into the afternoon, and hold a normal Tokyo bedtime even when wide awake. On a nine-hour shift, steady daily repetition over about a week is what finally closes the gap.
Calculate your personal plan
Get a day-by-day schedule tailored to your exact departure time and sleep habits, with this route already filled in.
Sources
- U.S. Centers for Disease Control and Prevention – CDC Yellow Book, “Jet Lag” chapter – eastward travel harder, morning light for phase advance.
- NHS – “Jet lag” (nhs.uk/conditions/jet-lag/), last reviewed 31 May 2023.
- Eastman CI & Burgess HJ (2009), Sleep Medicine Clinics – phase-advance scheduling for eastward travel.
- IANA Time Zone Database – offsets for Europe/London and Asia/Tokyo (Japan has no DST).