Should I sleep on the London to Tokyo flight?

    Yes — on London → Tokyo you are advancing your clock 8 hours eastward on a 12-hour flight, so sleeping in the air is the single most useful thing you can do; you land into a Tokyo morning that your body reads as the middle of the night.

    Flight time
    11h 37m to 13h 5m
    9,592 km
    Body-clock shift
    8 hours
    eastward
    To adjust
    8 days
    severe jet lag

    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 00:00 — that gap is what the flight can start closing.
    • Skip the second meal service, use an eye mask and earplugs, and stop caffeine at least 8 hours before your target sleep window.
    • Expect about 8 days to adjust after landing (severe jet lag).

    Day 1 in Tokyo

    • 07:00–09:00Seek bright light
    • 12:00Last caffeine
    • 20:00–04:00Target sleep window

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    Evidence-based recommendations

    Each recommendation below is graded by how strongly published research supports it, with the source it comes from. Optimal timing depends on your travel direction, the number of time zones crossed and your own circadian phase, so treat the schedule as a starting point.

    • Seek morning light

      Strong

      Bright light after your destination wake time helps advance your body clock when travelling east.

      CDC Yellow Book 2026
    • Limit light in the local evening

      Strong

      Light at the wrong hour can push your clock the opposite way, so dim screens and lights before your target bedtime.

      NIH — Circadian rhythms
    • Shift bedtime earlier before departure

      Moderate

      Moving sleep and wake times 30-60 minutes earlier for a few nights gives your clock a head start on an eastward trip.

      CDC Yellow Book 2026
    • Live on destination time on arrival

      Moderate

      Sleeping, eating and being active on local time gives your body consistent cues about the new day.

      CDC Yellow Book 2026
    • Consider timed melatonin

      Moderate

      Low-dose melatonin near the local bedtime can help with sleep timing after crossing several zones; timing matters more than dose.

      Cochrane review — Melatonin for jet lag
    • Use caffeine early, not late

      Practical advice

      Caffeine can help you stay awake during local daytime, but late doses tend to delay sleep onset.

      CDC Yellow Book 2026
    • Protect sleep around the flight

      Practical advice

      Arriving without a large sleep debt makes the first days easier, even when few time zones are involved.

      CDC Yellow Book 2026

    How we grade evidence

    Strong
    Consistently supported by controlled circadian research and current public-health guidance.
    Moderate
    Supported by research, but effect size and best timing vary between individuals and studies.
    Practical advice
    Sensible travel habits with limited direct evidence for shifting the body clock.

    This is general travel information, not medical advice. Talk to a clinician before using melatonin or sleep medication, especially if you are pregnant, take other medication or have a sleep disorder.

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