Jet lag from Hong Kong to Chicago: what to expect
Fly Hong Kong to Chicago and local time runs 10 hours ahead of your body. Land at 21:45 and your body still thinks it's 11:45 in Hong Kong. For your body, that's morning. At 23:00 in Chicago, it's 13:00 for you.
That's an eastward shift on the map, but the plan takes the long way round: it moves your clock later each day, 14 hours in all instead of 10. Near the far side of the world a clock could in principle shift either way, and adapting by delay is the more common route S1. The engine plans it both ways and keeps the one that reaches Chicago time sooner.
How long does jet lag last from Hong Kong to Chicago?
Your clock will adapt the long way round: later each day, not earlier.
Unaided, eastward shifts settle at around a day per time zone: about 10 days for this one. S6 S7
This plan targets 9 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 20:00, early by Chicago's clock, and it moves later night by night, reaching 23:00 by night 9.
Studies of aircrew point the same way: after large shifts, westward adaptation runs roughly 50% faster than eastward S6 S8. It's why the plan goes the long way round here.
What does the plan say for a typical Hong Kong to Chicago flight?
- Departs
- 20:00 Hong Kong time
- Lands
- 21:45 Chicago time
- In the air
- about 15h 45m (estimate)
- Light, the first full day
- 13:55–14:55 Seek bright light (delay shift)
- Last caffeine, landing day
- 07:00 on the plane
- Caffeine after landing
- 23:00–12:00 landing night into the next day
- First night's sleep
- 20:00–04:00 the evening after you land
This example leaves Hong Kong at 20:00 in the evening and lands in Chicago at 21:45 late at night, 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 going the other way, so you land on the same date you took off.
In July the gap is 11 hours, not 10, because Chicago moves its clocks and Hong Kong doesn't.
The plan puts about 6 hours of sleep on board, from 15:00 Chicago time. You're awake again before you land.
You land at 21:45 and stay up through the local night: at 02:00 in Chicago your body thinks it's 16:00 in Hong Kong, its afternoon. The plan has no arrival nap, just a 30-minute nap at 05:00. The first full night comes the next evening, at 20:00.
The day before you fly, the plan keeps your morning dim, 07:00–09:00 Hong Kong time, and the sun is up in Hong Kong by about 07:05 in January, so plan on sunglasses for the commute.
Your last coffee on the plane is at 07:00 Chicago time. After you land the plan opens caffeine again at 23:00, until 12:00 the next day: at 23:00 your body thinks it's 13:00 in Hong Kong, the middle of its day, and the plan keeps you up through the night on purpose.
January days are short in Chicago: about 10 hours of daylight. In January the sun is up in Chicago from about 07:13 to 16:50, so the 13:55 light step the day after landing is daylight. Outside is the easy way to get it.
You land too late in the day for a light step on landing day, so the first one is the next day, at 13:55.
What helps after flying east to Chicago?
Because the plan moves your clock later, the light advice for westward trips applies here, even though you fly east: 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 the mechanism, and the plan's light steps above already follow it.
And the flight home from Chicago?
Chicago to Hong Kong is the same 10 hours the other way, westward. It's the easier direction: about 7 days unaided, and the plan targets 6. Jet lag from Chicago to Hong Kong has the details.
More routes from Hong Kong
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.