Jet lag from Chicago to Hong Kong: what to expect
Fly Chicago to Hong Kong and local time runs 10 hours behind your body. Land at 16:45 and your body still thinks it's 02:45 in Chicago. That's the middle of your body's night. At 23:00 in Hong Kong, it's 09:00 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.
At 10 hours you're close to the far side of the world, where a clock could in principle shift either way. Adapting by delay is the more common route at that distance S1.
How long does jet lag last from Chicago to Hong Kong?
Unaided, westward shifts settle somewhat faster than a day per time zone: about 7 days for this one. S6 S7
This plan targets 6 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 evening after you land, the plan's bedtime is 20:10, early by Hong Kong's clock, and it moves later night by night, reaching 23:00 by night 6.
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 Chicago to Hong Kong flight?
- Departs
- 11:00 Chicago time
- Lands
- 16:45 Hong Kong time +1 day
- In the air
- about 15h 45m (estimate)
- Light, the first full day
- 17:55–18:55 Seek bright light (delay shift)
- Last caffeine, landing day
- 07:15 on the plane
- Caffeine after landing
- 23:10–12:15 landing night into the next day
- Nap after landing
- 18:15 Nap when you can lie down, up to 90 min
- First night's sleep
- 20:10–04:10 the evening after you land
Westbound flights often go by day, so this example leaves Chicago at 11:00 and lands in Hong Kong at 16:45 in the afternoon, after about 15h 45m 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 16 hours.
In July the gap is 11 hours, not 10, because Chicago moves its clocks for summer and Hong Kong doesn't.
The plan gives you 65 minutes of sleep on board, from 15:10 to 16:15 Hong Kong time, ending half an hour before you land. What's left of that night becomes a nap on the ground at 18:15: "Nap when you can lie down, up to 90 min".
You land at 16:45 and stay up through the local night, apart from the 18:15 nap: at 02:00 in Hong Kong your body thinks it's 12:00 in Chicago, the middle of its day. It adds a 30-minute nap at 07:45. The first full night comes the next evening, at 20:10.
The day before you fly, the plan keeps your morning dim, 07:00–09:00 Chicago time, and the sun is up in Chicago by about 07:15 in January, so plan on sunglasses for the commute.
Your last coffee on the plane is at 07:15 Hong Kong time. After you land the plan opens caffeine again at 23:10, until 12:15 the next day: at 23:10 your body thinks it's 09:10 in Chicago, its morning, and the plan keeps you up through the night on purpose.
The sun sets in Hong Kong at about 18:04 in January, partway through the 17:55 light step the day after landing, so start it outside.
You land too late in the day for a light step on landing day, so the first one is the next day, at 17:55.
What helps after flying west to Hong Kong?
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 Hong Kong?
Hong Kong to Chicago is the same 10 hours the other way, eastward. It's the harder direction: about 10 days unaided, and the plan targets 9. Jet lag from Hong Kong to Chicago has the details.
More routes from Chicago
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.