Jet lag is not just tiredness. It is a full-body circadian disruption: your master clock says it is 3 a.m. while the local restaurant is serving lunch. Sleep, digestion, body temperature, hormone release, and cognitive performance all run on the old schedule, and they resynchronize at different speeds, which is why you can feel simultaneously wired and exhausted.
The good news: jet lag is one of the most studied problems in sleep medicine, and the interventions with real evidence are specific and actionable. Here is the protocol, organized by what to do before, during, and after the flight, with separate guidance for eastward and westward travel.
Why Eastward Is Harder Than Westward
Your internal clock runs slightly longer than 24 hours, so your biology finds it easier to delay (stay up later, the westward direction) than to advance (fall asleep earlier, the eastward direction). Unaided, the clock shifts about one hour per day eastward and about one and a half hours per day westward. A six-hour eastward jump, New York to Paris, takes roughly six days to fully resolve without intervention. Westward, the same distance takes about four. Eastward travel needs the full protocol. Westward travel is more forgiving.
Jet Lag Protocols: East vs West
Your direction of travel changes the strategy. Pick your tab for light timing, sleep, and meal guidance.
The harder direction
Eastbound travel shortens your day. The goal is to advance your clock.
- Before: shift bedtime 30 to 60 minutes earlier for 2 to 3 nights
- Light: seek bright morning light at your destination; avoid bright light late in the day
- Sleep: a low dose of melatonin in the early evening may help; talk to your doctor first
- Meals: eat on destination time from landing day
- Expect: about 1 day of adjustment per time zone crossed
The easier direction
Westbound travel lengthens your day. The goal is to delay your clock.
- Before: shift bedtime 30 to 60 minutes later for 2 to 3 nights
- Light: seek bright light in the late afternoon and evening at your destination
- Sleep: keep a dark cool room; morning light avoidance matters less here
- Meals: eat on destination time; a later dinner helps anchor the delay
- Expect: roughly half a day of adjustment per time zone
The meal timing reset
Small studies, including the well-known Argonne protocol, suggest a pre-flight fast can help reset your food clock.
- Method: fast 12 to 16 hours before breakfast at your destination
- During: water and plain tea are fine; avoid alcohol and heavy airline meals
- Break: eat a protein-rich breakfast on destination time
- Evidence: promising but small studies; treat as experimental
- Skip it if: you are pregnant, nursing, diabetic, or have a history of disordered eating
Before You Fly: Pre-Shift Your Clock
The highest-leverage move happens before departure. Starting three days before travel, shift your sleep schedule toward the destination by one hour per day: flying east, go to bed and wake up one hour earlier each day; flying west, one hour later each day. Pair the shift with light, the strongest clock-resetting signal. For eastward pre-shifting, get bright light in the morning and dim light in the evening. For westward, seek bright light in the evening and keep mornings dim. Light therapy boxes (10,000 lux for 20 to 30 minutes) work when daylight is unavailable, though morning sunlight is free and effective.
Melatonin: What the Cochrane Review Found
A Cochrane systematic review of 10 randomized controlled trials found that melatonin, taken close to the target bedtime at the destination, reduced jet lag in 8 of the 10 trials, with an estimated number-needed-to-treat of 2. Doses between 0.5 mg and 5 mg were similarly effective, with 5 mg helping people fall asleep faster than 0.5 mg. Doses above 5 mg showed no additional benefit. Timing is the critical variable: melatonin should be taken at the destination's bedtime, roughly 10 p.m. to midnight local time, starting on the day of arrival and continuing for two to four nights. Taking it at the wrong time can shift the clock in the wrong direction. Melatonin is sold over the counter in the US but regulated as a prescription drug in many other countries, and product quality varies enormously; a USP-verified brand is worth seeking. People with epilepsy, those taking blood thinners, and pregnant women should consult a doctor first. Melatonin is not a sedative for the flight itself.
Light Timing on Arrival: The Direction-Specific Rules
Flying eastward, you need to advance your clock: seek bright light in the morning at the destination and avoid bright light in the evening. Morning sunlight on arrival day is the priority intervention; sunglasses in the evening help. Flying westward, you need to delay: seek bright light in the late afternoon and evening, minimize morning light exposure for the first day or two. For trips crossing more than about eight time zones, the clock may adapt faster by delaying instead of advancing, since the body delays more easily.
During the Flight
Set your watch to destination time as soon as you board and start living on it mentally. If it is nighttime at your destination, try to sleep; if daytime, stay awake. For sleep on the plane: an eye mask, earplugs or noise-canceling headphones, and a neck pillow you have actually tested. Avoid alcohol as a sleep aid: it fragments sleep and dehydrates. Use caffeine strategically to stay awake during destination daytime, and stop eight to ten hours before destination bedtime. Hydrate deliberately and move periodically; compression socks are worth considering on flights over four hours. Eat on destination schedule if you can: meal timing is a secondary clock-setter.
Fasting and the Argonne Diet: Interesting, Unproven
The claim that fasting for 16 hours before arrival resets the clock traces to 2008 mouse research from Clifford Saper's lab at Harvard, and it has not been tested as a jet lag intervention in humans. Treat it as an interesting hypothesis, not a protocol. The older Argonne anti-jet-lag diet has a small amount of supportive data from its originators and has never been validated in independent trials. The harmless version, eat meals on destination schedule from the day of travel, is worth doing regardless.
The First 48 Hours: Putting It Together
Day of arrival, eastward: get morning sunlight, stay active and outdoors during the day, avoid napping (or cap naps at 20 minutes before 3 p.m.), take 0.5 to 5 mg melatonin at local bedtime, keep the room dark and cool. Day of arrival, westward: minimize morning light, seek afternoon and evening light, stay up to a reasonable local bedtime, melatonin at local bedtime if needed. Both directions: exercise helps, keep meals on local time, be patient with digestion. Most travelers feel substantially better by day three and fully adapted within a day per time zone crossed.
When to Consider More
Frequent long-haul travelers, shift workers, and flight crew face chronic circadian disruption, which carries real long-term health associations: talk to a sleep medicine specialist about a personalized light and melatonin schedule rather than improvising trip to trip. For the occasional traveler, the protocol above captures nearly everything the evidence supports. See also our guide to morning sunlight for circadian rhythm, the evidence on mouth taping for sleep, and magnesium for sleep.
