Jet lag recovery — the evidence-based protocol

Jet lag isn't just sleepiness — it's a desynchronisation between your circadian clock (which is set by your previous time zone) and your environment (the new one). The clock catches up at a fixed rate; the only question is how fast you help or hinder it.

The asymmetry: east is harder

Your circadian clock has an intrinsic period slightly longer than 24 hours (averaging ~24.2). The body finds it easier to delay (go later — westward travel) than to advance (go earlier — eastward travel). The rule of thumb that sleep researchers use:

• Eastward: 1 hour of recovery per day
• Westward: 1.5 hours of recovery per day

So a 6-hour eastward trip (e.g. Singapore → London) takes about 6 days to fully adjust. The same 6-hour westward trip back home takes about 4 days.

Use the Jet-Lag Recovery Planner for a day-by-day schedule.

Light is the master signal

Of all the things that adjust your circadian clock, light is by far the strongest. Caffeine and meals matter, but they fine-tune what light has already set. The protocol is direction-dependent:

Eastward (you need to wake up earlier)

• Get bright morning light in the new time zone — outside if possible, the first 2 hours after waking
• Avoid bright light for 2 hours before target bedtime — including phone screens; use blue-light filters or amber glasses
• Eat breakfast on local time even if not hungry — this anchors meal-related circadian signals

Westward (you need to stay up later)

• Get bright evening light — late afternoon and early evening sun
• Avoid bright morning light for the first 2 hours after waking — wear dark sunglasses outside
• Eat dinner on local time, late if necessary

What about melatonin?

Melatonin is a hormone, not a sleeping pill. Used correctly, it can help shift the clock; used wrongly, it does little. The protocol most sleep researchers recommend:

• 0.3–1mg (yes, that low — the 5mg/10mg pills sold in pharmacies are massively over-dosed)
• Eastward: take 5–6 hours before target bedtime (i.e. early afternoon)
• Westward: take at target bedtime

Melatonin is not a substitute for the light protocol. Without the light, the hormone has limited effect.

What about caffeine?

Caffeine is useful as a stimulant during the day, but the timing rule still applies. No caffeine within 8 hours of target bedtime in the new time zone — for the entire adjustment period, not just the first day.

Meal timing

The body has secondary clocks in the digestive system that are entrained partly by meal timing. Eat on local time even if not hungry. Skip in-flight meals that fall at "wrong" times for your destination.

Other things that help

• Hydration. Cabin air is 10–20% humidity. Drink water aggressively in flight; dehydration alone causes "jet lag" symptoms.
• Sleep on the plane only if it aligns with your destination's night. Otherwise stay awake and adjust on arrival.
• Skip alcohol on the flight. It fragments sleep and worsens dehydration.
• Move. Walk the aisle, stretch in your seat. Sedentary posture worsens swelling and stiffness, both of which compound the next day's fatigue.

What doesn't work (or barely)

• Anti-jet-lag diets that prescribe specific foods. The studies are weak.
• Sleeping pills. They mask symptoms; they don't shift the clock. Use them sparingly if at all, and never combined with alcohol.
• "Just power through it." This works only for trips of 1–2 days where you don't really adjust at all and recover after returning home.

A short version

1. Look up your direction (east or west) and time-zone shift.
2. Figure out target sleep and wake times in the new zone.
3. Get bright light at the right time, avoid it at the wrong time.
4. Eat on local time. Stop caffeine 8 hours before bed.
5. Optionally, take 0.3–1mg melatonin at the right time.
6. Be patient. The clock catches up at its own pace; your job is not to fight it.