How to Beat Jet Lag: A Simple Time Zone Plan for Long Flights

By HSP · Published October 20, 2026 · 7 min read · Health & Fitness

You land after a long flight, the hotel clock says 9 a.m., and your body is sure it is midnight. That gap between the clock on the wall and the clock in your head is jet lag. It cannot be avoided completely, but a little planning can shave days off it. This guide shows how to work out how big your time jump is, how long you can expect to feel off, and what to do before, during and after the flight. It is general information, not medical advice.

What jet lag actually is

Your body runs on an internal clock that is set mainly by light. When you cross several time zones quickly, that clock is still running on home time while everything around you has moved. The result is trouble falling asleep at night, waking too early or too late, feeling sleepy in the afternoon, poor concentration and sometimes an upset stomach. The NHS lists these as the main symptoms and notes that jet lag usually settles within a few days as you adjust.

Doctors use the term jet lag disorder when the symptoms follow travel across at least two time zones. Crossing one zone, for example Toronto to Winnipeg, rarely causes real trouble.

Step 1: Count the time zones you cross

The size of the jump matters more than the length of the flight. A long overnight flight from Toronto to Santiago, Chile changes the clock by only about an hour, while Toronto to Delhi moves it by more than nine hours. Put your home city and destination into our time zone converter to see the exact difference on your travel date, or keep both cities side by side on the world clock. If you are not sure how offsets work, our guide on finding the time difference between cities explains it step by step.

Check the date as well as the cities. Clocks change on different weekends in different countries. In 2026 much of Europe falls back on 25 October, while Canada and most of the US fall back on 1 November. For that one week, Toronto is only 4 hours behind London instead of the usual 5. Our daylight saving guide lists the dates.

Step 2: Work out the direction and the recovery time

Flying east (for example North America to Europe or India) means your destination clock is ahead, so you need to go to bed earlier than your body wants. Flying west means staying up later, which most people find easier because the natural body clock runs slightly longer than 24 hours. According to the CDC Yellow Book, travellers adapt on average about 1 hour per day after flying east and about 1.5 hours per day after flying west.

That gives a simple rule of thumb you can work out with a calculator:

• East: recovery days ≈ hours of time difference ÷ 1
• West: recovery days ≈ hours of time difference ÷ 1.5

These are averages. Some people adjust faster, some slower, and good light timing (step 5) can speed things up.

Worked examples

Toronto runs on EDT (UTC−4) until 1 November and India runs on IST (UTC+5:30) all year, so the gap is 9.5 hours. After 1 November it grows to 10.5 hours. You will feel much better well before the full adjustment, usually after the first two or three good nights, but these numbers explain why the first week of a big trip can feel foggy.

Step 3: Before you fly

• Shift your sleep a little. The CDC suggests moving your sleep about 1 hour earlier per day (going east) or 1 hour later per day (going west) for the 2–3 days before the trip. Three days of shifting can cut a 9.5-hour jump to roughly 6.5 hours.
• Pick your flight with arrival time in mind. Arriving in the morning or early afternoon gives you a full day of daylight to reset. A late-night arrival can work too if you can go straight to bed.
• Start the trip rested. A short night before the flight makes jet lag worse. Use the sleep calculator to pick a bedtime that lets you wake at the end of a sleep cycle on the day you leave. Our guide to how much sleep you need gives the targets by age.

Step 4: On the plane

• Switch your watch to destination time when you board, and plan meals and sleep around it.
• Sleep if it is night where you are going. An eye mask and earplugs help. If it is daytime there, try to stay awake, watch a film, walk the aisle.
• Drink water, go easy on alcohol and caffeine. Both the NHS and the CDC say dehydration and alcohol can make symptoms worse. Our water intake calculator gives a sensible daily target, and cabin air is dry, so sip regularly.
• Move. Stretch and walk around the cabin every so often on long flights.

Step 5: After you land, use light on purpose

Light is the strongest signal your body clock has. The CDC guidance is:

• After flying east: get bright daylight in the morning and keep the evening dim. Morning light pulls your clock earlier.
• After flying west: avoid very bright light early in the morning and get daylight in the late afternoon and evening. Evening light pushes your clock later.
• Nap short. A 20–30 minute nap can help you get through the first afternoon. Long naps make it harder to sleep at night.
• Eat and sleep on local time from day one, and set an alarm so you do not sleep through the morning.

Some people ask about melatonin or sleeping tablets. The CDC describes timed melatonin as one option doctors may suggest, while the NHS does not recommend melatonin for jet lag because of limited evidence. Talk to a doctor or pharmacist before taking any sleep aid, especially for children, during pregnancy or alongside other medicines.

Short trips are different

If you are away for only two or three days, it can be easier not to adjust at all. Both the NHS and the CDC mention keeping close to your home sleep times on very short trips, so you do not have to shift twice. Book meetings for times that fall in your normal waking hours. Our guide to planning meetings across time zones shows how to find a slot that suits both sides.

Planning your trip

If you are still choosing flights, our flights hub lets you compare routes and fares, with dedicated pages for popular trips such as Toronto to Delhi and Toronto to London. The travel checklist covers documents, chargers and the other things that are easy to forget when you are tired. For more on body clocks, see how sleep cycles work and our explainer on converting time zones.

VSH take: it is easy to blame the long flight, but the bigger factors are the size of the clock jump and what you do with daylight on day one. A three-day pre-shift and one sunny morning walk after an eastbound flight do more than any gadget.

General information only, not medical advice. Updated 20 October 2026. Adaptation rates from the CDC Yellow Book 2026 chapter on jet lag disorder; symptom and self-care advice from the NHS.