Jet Lag From Los Angeles to Tokyo, Seoul, Shanghai and Hong Kong: Out Is Easier Than Back
Los Angeles to Tokyo looks like a 16 or 17 hour jump on the clock. Your body does not see it that way. The shortest path for the body clock is a 7 to 8 hour delay, the direction it drifts on its own, so the outbound leg is the easier one. The flight home is the same distance as an advance, and that is the leg most people remember as the bad one. This guide gives the calculator's plan for both directions across Tokyo, Seoul, Shanghai and Hong Kong.
By Reede Taylor · Published September 9, 2026 · Reviewed September 9, 2026
Why this route is hard
The clock difference between Los Angeles and Tokyo is 16 hours in winter and 17 in summer. That number is nearly useless for planning, because a body clock does not shift 16 hours in one direction when it can shift 8 in the other. The Jet Lag Calculator resolves the trip the way the circadian research does, by the shortest path: Los Angeles to Tokyo is a 7 hour delay in winter and 8 in summer. Your bedtime has to move later, not earlier. Tokyo to Los Angeles is the reverse, a 7 or 8 hour advance.
That single fact explains the whole pattern of this route. Delaying the clock is the direction it drifts anyway, since the human circadian period runs slightly longer than 24 hours, so westward adaptation runs at roughly three quarters of a day per zone. Advancing fights the drift and runs at about a day per zone. The calculator gives around 5 to 6 days to adapt going out and 7 to 8 coming home. Many articles describe the trip the other way round; the tool, and the research it is built on, do not.
The flights shape the days either way. Most Los Angeles departures to Tokyo, Seoul, Shanghai and Hong Kong leave between 10 AM and 2 PM and take 11 to 15 hours, landing mid to late afternoon on the following calendar day. You arrive after a long daylight flight, at what feels like the small hours of the morning, with an evening still to get through. Coming home, flights leave in the late afternoon or evening and land in Los Angeles in the morning of the same calendar day you left, which is the middle of the night on a Tokyo clock.
Shanghai and Hong Kong sit one hour behind Tokyo and Seoul. That makes the delay an hour bigger going out, 8 to 9 hours, and the advance an hour bigger coming home. Each adds about a day of recovery.
Flying out
Enter your route in the calculator and it produces a plan in three parts: prep nights before you fly, the flight, and arrival days. Here is what it does for Los Angeles to Tokyo with two prep days, a usual bedtime of 10:30 PM and a winter departure. Seoul is identical; Shanghai and Hong Kong run about an hour further in every step.
Prep nights. Each prep night moves bedtime an hour later, the opposite of a European trip: 11:30 PM two nights before, 12:30 AM the night before, with wake time sliding later to match. Bright light in the evening pushes the clock later; dim light in the first hour after waking stops the morning from pulling it back. Two prep nights take two hours off the seven you need to shift.
The flight. No scheduled sleep window. The calculator's flight guidance is short: a nap of an hour or two around the middle of the flight, no more, and no alcohol. You want to land tired enough to sleep early. The nap calculator covers how long a nap can run before it turns into a sleep that leaves you wide awake at midnight in Tokyo.
First night in Tokyo. The plan's first sleep window runs 7:15 PM to 3:15 AM Tokyo time. That is early, and it is meant to be. 7 PM in Tokyo is 2 AM in Los Angeles, and after two prep nights of later bedtime your body is at its limit. Sleep early, wake early, and treat a 3 or 4 AM wake as the plan working, not failing. The light window on the arrival afternoon runs from about 4 PM to 7 PM: stay outside or near windows until it is time for bed, and keep the hour after waking dim.
Days two and three. Bedtime moves about 1 hour 45 minutes later each night, so night two is around 9 PM and night three is your usual 10:30 PM, now on Tokyo time. Evening light and a dim first hour awake keep the delay moving. The plan reaches Tokyo time in 5 days in winter and 6 in summer. Shanghai and Hong Kong take 6 days either way.
If you fly without prep nights, or you are reading this on arrival, switch the calculator to "I already landed". The first sleep window then runs 5:15 PM to 1:15 AM Tokyo time, with an afternoon light window from about 2 PM, and the same 1 hour 45 minute steps after that, reaching Tokyo time in 4 days.
Open the outbound plan for Los Angeles to Tokyo or Seoul, or the Shanghai and Hong Kong version. Already there? Start from tonight.
Flying home
Tokyo to Los Angeles is a 7 hour advance in winter and 8 in summer, and it is the harder leg. The calculator estimates about 7 to 8 days of recovery, against 5 to 6 going out. From Shanghai or Hong Kong the advance is 8 to 9 hours and the estimate is 8 to 9 days.
The flight arrives at an awkward hour. A late-afternoon departure from Tokyo lands in Los Angeles around 10 AM on the same calendar day, which is 3 AM on your Tokyo clock. You have gained a day and lost a night.
The plan with two prep nights moves bedtime an hour earlier each night before you fly: 9:30 PM then 8:30 PM Tokyo time, with morning light after waking and dim light in the two hours before bed. On the night you land, the first sleep window runs 2 AM to 10 AM Los Angeles time. That is not a mistake. 2 AM in Los Angeles is 7 PM in Tokyo after the prep shift, and it is the earliest your body will sleep. Expect the first evening at home to feel long, and the first morning to start late. Bright light after waking, from 10 AM to 11:30 AM on the plan, does most of the work; the two hours before bed are the avoid-light window, so keep the late evening dim.
Bedtime then moves about 90 minutes earlier each night: around 12:30 AM on night two, 11 PM on night three, and your usual time by night four, with the plan reaching Los Angeles time in 6 days. The symptom to expect is the reverse of the outbound leg: hard to fall asleep, hard to wake, and an afternoon slump around what your body still thinks is 3 AM. Do not nap through it if you can avoid it; if you must, keep it under 30 minutes and before 3 PM.
Open the return plan for Tokyo or Seoul to Los Angeles, or the Shanghai and Hong Kong to Los Angeles version.
Short trips
A trip of three nights or fewer is not worth adapting to, and on this route that is especially true because the two legs pull in opposite directions. Adapt for three days in Tokyo and you arrive home with your clock delayed 5 hours, then have to advance it 12. The research advice for short trips is to stay close to home time: on Los Angeles time, Tokyo's afternoon and evening are your morning and midday, so schedule meetings from midday onward, sleep late by local standards, and treat the early morning as your night.
For four to six nights, adapt going out but expect to be still adjusting when you fly home. For a week or more, run both plans in full; the prep nights before the return, moving bedtime earlier while still in Tokyo, are the single most useful part, because they turn an 8 hour advance into a 6 hour one before you board.
Where staying on home time is not possible, use the "I already landed" plan for the nights you are there and stop when you leave. Two nights of the plan move you about 3.5 hours toward Tokyo time, which is enough to make a 9 AM meeting workable.
Light, melatonin and caffeine
The levers are the same as any jet lag plan; what changes on this route is that they point in opposite directions on the two legs.
Light. Going out, evening light delays the clock and morning light pulls it back, so stay in daylight through the Tokyo afternoon and evening and keep the first hour after waking dim, including the hotel bathroom. Coming home, it flips: morning light after waking advances the clock and evening light delays it, so get outside soon after waking in Los Angeles and keep the two hours before bed dim. Outdoor light is many times stronger than any indoor lamp, even through cloud.
Melatonin. The Cochrane review by Herxheimer and Petrie found the strongest evidence for eastward travel of five or more zones, with melatonin taken close to the target bedtime at the destination. That is the return leg on this route. For westward travel the evidence is weaker but still favourable for sleep onset, and the westward studies took it shortly before the desired sleep time. The doses studied ran from 0.5 to 5 mg, with the low end doing as well as the high. Whether any of that applies to you is a question for your doctor or pharmacist. The Melatonin Timing Calculator shows the timing the studies used for each direction.
Caffeine. On the outbound leg the trap is coffee on the arrival afternoon. With a 7:15 PM first-night bedtime, the Caffeine Cutoff Calculator puts the last coffee at about 10:45 AM Tokyo time, which is before you land; a coffee at 4 PM in Tokyo is a coffee at midnight for your body. Coming home the first-night bedtime is 2 AM, so the cutoff sits around 5:30 PM and moves earlier each night as the plan advances.
Frequently asked questions
Why is jet lag worse flying back from Japan?
Because the two legs shift your body clock in opposite directions. Los Angeles to Tokyo is resolved by the body as a 7 to 8 hour delay, moving bedtime later, which is the way the clock drifts naturally. Tokyo to Los Angeles is a 7 to 8 hour advance, moving bedtime earlier, which the clock resists. The calculator estimates about 5 to 6 days of recovery going out and 7 to 8 coming home, and most travellers' experience matches that.
How many days does it take to recover from jet lag from LAX to Tokyo?
About 5 days in winter and 6 in summer, using the research rate of roughly 0.75 days per time zone for westward travel, since the shift is 7 hours when Los Angeles is on standard time and 8 hours when it is on daylight time. With two prep nights of later bedtime the calculator's plan reaches Tokyo time in 5 to 6 days, and most people are functional by day three.
Should I sleep on the flight to Tokyo?
Only briefly. Most Los Angeles departures leave late morning and land in Tokyo mid to late afternoon the next calendar day, which is the small hours of the morning on your body clock by the time you arrive. A nap of an hour or two in the middle of the flight helps; a full sleep does not, because you want to be tired enough for an early first night in Tokyo. Keep the cabin bright while awake and avoid alcohol, which fragments what sleep you do get.
What time should I go to bed the first night in Tokyo?
Early. The calculator's first sleep window after two prep nights runs from about 7 PM to 3 AM Tokyo time, because 7 PM in Tokyo is 2 AM in Los Angeles and your body has been up since the previous morning. Going to bed early and waking early is the correct shape of night one on a westward delay. Each following night moves bedtime about 1 hour 45 minutes later, so by night three you are close to a normal Tokyo bedtime.
Is Seoul the same as Tokyo for jet lag?
Yes. Seoul and Tokyo share the same time zone, so the shift, direction and plan are identical. Shanghai and Hong Kong are one hour behind them, which makes the westward delay one hour larger going out (8 to 9 hours) and the advance one hour larger coming home. That adds about a day of recovery in each direction.
Key research
- Eastman, C.I. & Burgess, H.J. (2009). How to travel the world without jet lag. Sleep Medicine Clinics, 4(2), 241–255. Adaptation rates by direction, and the rule that shifts beyond about nine hours may go either way.
- Waterhouse, J., Reilly, T., Atkinson, G. & Edwards, B. (2007). Jet lag: trends and coping strategies. The Lancet, 369(9567), 1117–1129. Westward delay is easier than eastward advance for the same number of zones.
- Herxheimer, A. & Petrie, K.J. (2002). Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews, (2), CD001520. Evidence is stronger for eastward than westward travel.
- Sack, R.L. (2010). Jet lag. New England Journal of Medicine, 362(5), 440–447. Clinical review covering light timing, sleep scheduling and symptom duration.
Educational information, not medical advice. Consult a healthcare provider for sleep disorders or before taking any supplement.