Jet lag plan
Tokyo is 1 hour ahead of Hong Kong. You're traveling east — the harder direction. Your body must advance its clock.
About 2,876 km northeast · approximately 4.3-hour non-stop flight · a long-haul flight.
The route from Hong Kong, Hong Kong to Tokyo, Japan covers roughly 2,876 kilometres in a northeast direction. At standard jet cruise speed plus a one-hour allowance for taxi, climb, and descent, a non-stop flight takes about 4.3 hours. Both cities sit in the northern hemisphere, so the seasonal direction of daylight (longer days in June, shorter in December) matches between origin and destination.
Hong Kong is in the tropics, so day length varies only slightly across the year. Light cues for the circadian system stay strong year-round. Tokyo is in the temperate zone. Day length varies by four to six hours between summer and winter, so the season of your trip materially affects available morning and evening light.
Standard 09:00–18:00 working hours at both ends of this route overlap by approximately 8 hours. In Hong Kong that window runs 09:00 to 17:00; in Tokyo it is 10:00 to 18:00. This is the realistic window for live meetings, customer calls, or pair work without forcing either end out of normal hours.
Neither city observes daylight saving time, so the hour offset on this route is fixed year-round. This makes recurring schedules and calendar invites with collaborators on the other end safer than for DST-observing pairs.
If you are a lark (morning type): Larks recover faster on eastward routes because their circadian phase is already advanced relative to the population. Plan to be in bed one hour earlier than your usual time for two or three nights before departure, and seek bright light immediately on waking at the destination. Most larks adjust to a 1-hour eastward shift in 2 days.
If you are a night owl (evening type): Owls struggle with eastward travel. Your biology resists advancing; a 1-hour eastward shift will typically take 3 days to clear, with the worst days being day two and three. Pre-trip phase advance (going to bed 30–60 minutes earlier per day for 1 days) and morning bright light at the destination are the highest-evidence interventions.
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The great-circle distance from Hong Kong to Tokyo is about 2,876 kilometres. A typical non-stop flight takes around 4.3 hours at standard cruise speed; routes with connections add two to four hours.
Tokyo is currently 1 hour ahead of Hong Kong. Neither city observes daylight saving time, so the hour offset on this route is fixed year-round. This makes recurring schedules and calendar invites with collaborators on the other end safer than for DST-observing pairs.
Eastward travel — which this route is — is the harder direction for most travellers. Your body must advance its clock, and the population shifts about one hour per day under good conditions. Expect 2 days to fully clear a 1-hour eastward shift.
For a shift of 1 hour, melatonin offers little benefit beyond what consistent light exposure already provides. The Cochrane review on jet-lag melatonin shows the strongest effects on shifts of five hours or more.
For a shift under two hours, pre-trip adjustment is usually not worth the effort.
Larks (morning types) recover faster on eastward routes because their circadian phase is already advanced relative to the population. Owls (evening types) typically need an extra day or two.