Your day-by-day recovery plan
| Day | Focus | What to do |
|---|---|---|
| 1 | Morning light exposure | Get bright light within 1 hour of local sunrise. Avoid bright light after 6 PM. Consider 0.5–1 mg melatonin 30 min before local bedtime. |
| 2 | Normalizing | Keep a fixed wake time. Morning light, daytime activity, consistent local bedtime. |
Why Jet Lag Happens — and How to Fix It
Jet lag is a mismatch between two clocks: the local time at your destination and your circadian rhythm, the roughly 24-hour internal timer that governs when you feel sleepy, hungry, and alert. That rhythm is set deep in the brain by the suprachiasmatic nucleus, and it does not care that your flight took twelve hours — it keeps running on home time until something forces it to shift.
The strongest signal that shifts the clock is light. Bright light in your biological morning pushes your rhythm earlier; light in the evening pushes it later. That is why the direction of travel changes the strategy: after an eastward flight you want morning sun and early nights, while after a westward flight you want afternoon light and to hold off sleep until local bedtime. Melatonin — the hormone your body releases as darkness falls — can reinforce the shift when taken at the right local time.
Direction matters because of a quirk of human biology: the natural circadian period is slightly longer than 24 hours, so delaying your clock (westward travel) is easier than advancing it (eastward). That is why the calculator above gives eastward trips a longer recovery estimate, and why the day-by-day plan for each direction prescribes opposite light strategies.
Recovery Time by Time Difference
| Time Difference | Westward Recovery | Eastward Recovery |
|---|---|---|
| 1–3 hours | 1–3 days | 2–5 days |
| 4–6 hours | 4–6 days | 6–9 days |
| 7–9 hours | 7–9 days | 10–14 days |
| 10–12 hours | 10–12 days | 15–18 days |
Frequently Asked Questions
How to recover from jet lag fast?
Anchor yourself to the destination schedule immediately: eat, sleep, and get light exposure at local times from day one. Morning light helps after eastward flights, afternoon light after westward ones. Keep naps under 20 minutes, stay hydrated, and avoid alcohol on arrival day.
How long does jet lag last?
A common rule of thumb is about one day of recovery per hour of time difference when flying west, and up to 1.5 days per hour when flying east. A 6-hour eastward trip can take 7–9 days to fully clear, while the same gap westward usually resolves in about 6.
Does melatonin help jet lag?
Yes — low-dose melatonin (0.5–1 mg) taken 30 minutes before your target local bedtime can help shift your body clock, especially after eastward flights. Timing matters more than dose. Talk to your doctor first if you take other medications or have a health condition.
Which direction is worse for jet lag?
Eastward travel is usually worse. Flying east shortens your day, forcing your body clock to advance — and most people's internal rhythm naturally runs slightly longer than 24 hours, so delaying (westward) comes more easily than advancing (eastward).