Jet lag from Los Angeles to Seoul: what to expect
Fly Los Angeles to Seoul and local time runs 7 hours behind your body. Land at 16:15 and your body still thinks it's 23:15 in Los Angeles. That's the middle of your body's night. At 23:00 in Seoul, it's 06:00 for you.
That's a westward shift: your clock has to move later, which is the way it drifts on its own S1. Expect to be sleepy early in the evening for the first few days, and awake before your alarm S1.
How long does jet lag last from Los Angeles to Seoul?
Unaided, westward shifts settle somewhat faster than a day per time zone: about 5 days for this one. S6 S7
This plan targets 4 days.
That's what the plan aims at, not a promise — bodies vary.
For this trip that's 1 day sooner than the unaided estimate, on the effort level that fits around a working day.
On night one the plan's bedtime is 18:10, early by Seoul's clock, and it moves later night by night, reaching 23:00 by night 5.
Studies of aircrew point the same way: after large shifts, westward adaptation runs roughly 50% faster than eastward S6 S8. This trip is on the quick side of that.
What does the plan say for a typical Los Angeles to Seoul flight?
- Departs
- 11:00 Los Angeles time
- Lands
- 16:15 Seoul time +1 day
- In the air
- about 12h 15m (estimate)
- Light, landing day
- 17:10–18:10 Seek bright light (delay shift)
- Last caffeine, landing day
- 10:15 on the plane
- Last caffeine, first full day
- 13:00
- First night's sleep
- 18:10–02:10
Westbound flights often go by day, so this example leaves Los Angeles at 11:00 and lands in Seoul at 16:15 in the afternoon, after about 12h 15m in the air.
The flight time is our estimate for a nonstop from the distance, and the trip is set in January. It's the default traveler from the calculator: usually asleep 23:00 to 07:00, no melatonin, Real Life effort.
You cross the date line, and it costs you a calendar day: leave on a Wednesday, land on Thursday, though the flight itself is under 13 hours.
In July the gap is 8 hours, not 7, because Los Angeles moves its clocks for summer and Seoul doesn't.
On board, the plan keeps you awake apart from a short nap at 06:00 Seoul time, saving the real sleep for the night in Seoul.
The day before you fly, the plan keeps your morning dim, 07:00–09:00 Los Angeles time, and the sun is up in Los Angeles by about 06:57 in January, so plan on sunglasses for the commute.
On landing day your last coffee comes on the plane, at 10:15 Seoul time, and the plan has none between landing and your first night's sleep. From 02:10, when you wake from that first sleep, it allows it again, until 13:00.
January days are short in Seoul: about 10 hours of daylight. The sun sets in Seoul at about 17:44 in January, partway through the 17:10 light step on landing day, so start it outside.
What helps after flying west to Seoul?
Going west, you want light before your body's low point, which usually means bright light in the evening and staying up a little later S1. Bright light first thing in the morning works against you. East vs west explains why this direction is the easier one.
On a shift this size, starting before you fly pays off. The Frontiers review describes moving bedtime 30 to 60 minutes later each day for 3 to 4 days before a westward trip S1. The plan's version is one night: bed at 00:00 the night before you fly, an hour later than usual.
And the flight home from Seoul?
Seoul to Los Angeles is the same 7 hours the other way, eastward. It's the harder direction: about 7 days unaided, and the plan targets 5. Jet lag from Seoul to Los Angeles has the details.
More routes from Los Angeles
Sources
Numbered from the site-wide source registry — every Delagged page uses the same numbering.
- S1 Roach GD, Sargent C. Interventions to Minimize Jet Lag After Westward and Eastward Flight. Frontiers in Physiology, 2019;10:927. doi:10.3389/fphys.2019.00927
- S6 Waterhouse J, Reilly T, Atkinson G, Edwards B. Jet lag: trends and coping strategies. The Lancet, 2007;369:1117–29. doi:10.1016/S0140-6736(07)60529-7
- S7 Eastman CI, Burgess HJ. How to travel the world without jet lag. Sleep Medicine Clinics, 2009;4:241–55. doi:10.1016/j.jsmc.2009.02.006
- S8 Samel A, et al. Aircrew adaptation after transmeridian flights, 1995. As cited in Waterhouse et al., The Lancet 2007 (S6). Full text Cited via S6.