Jet lag plan
London is 6 hours ahead of Chicago. You're traveling east — the harder direction. Your body must advance its clock.
About 6,353 km northeast · approximately 8.3-hour non-stop flight · an ultra-long-haul flight.
The route from Chicago, United States to London, United Kingdom covers roughly 6,353 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 8.3 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.
Chicago 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. London 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 3 hours. In Chicago that window runs 09:00 to 12:00; in London it is 15:00 to 18:00. This is the realistic window for live meetings, customer calls, or pair work without forcing either end out of normal hours.
Both cities observe daylight saving time. The hour offset on this route can shift by one hour twice a year (typically March and October/November), and the two clocks rarely change on the exact same date — expect a transient 1-hour mismatch for two to three weeks per transition.
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 6-hour eastward shift in 4 days.
If you are a night owl (evening type): Owls struggle with eastward travel. Your biology resists advancing; a 6-hour eastward shift will typically take 6 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 4 days) and morning bright light at the destination are the highest-evidence interventions.
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The great-circle distance from Chicago to London is about 6,353 kilometres. A typical non-stop flight takes around 8.3 hours at standard cruise speed; routes with connections add two to four hours.
London is currently 6 hours ahead of Chicago. Both cities observe daylight saving time. The hour offset on this route can shift by one hour twice a year (typically March and October/November), and the two clocks rarely change on the exact same date — expect a transient 1-hour mismatch for two to three weeks per transition.
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 6 days to fully clear a 6-hour eastward shift.
For a 6-hour shift, 0.3 to 0.5 mg of melatonin taken three to five hours before target bedtime at the destination is the dose supported by the Cochrane review. Higher doses (3–5 mg) do not advance phase better and increase morning grogginess. Start one day before departure.
Yes — for shifts of four hours or more, shifting bedtime and wake time by one hour per day, starting three days before departure, materially reduces post-arrival jet lag.
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.