How to get over jet lag faster
Jet lag is not tiredness. It is the specific misalignment between the clock inside you and the clock on the wall, and the difference matters — because sleeping more does not fix a misalignment. Timing light does.
The standard jet lag advice — drink water, avoid alcohol, get some sun — is not wrong, but it is so vague that it barely helps. The useful version requires one extra piece of information: which direction you need to shift, and therefore when light will help rather than hurt.
What jet lag actually is
Your circadian rhythm governs sleepiness, alertness, core temperature, hormone release and digestion on a roughly twenty-four-hour cycle, anchored to the light-dark pattern where you live. Fly across several time zones and that anchor moves instantly while your internal clock does not.
The result is a mismatch. Your body is producing melatonin at 2pm local time and cortisol at 11pm. That is why jet lag involves not only bad sleep but daytime fog, digestive upset and low mood — every system running on the old schedule is now out of step with the day around it.
Which is also why the intuitive fix fails. Sleeping longer does not correct a phase misalignment. Only re-anchoring the clock does, and light is the anchor.
Why flying east is worse
Almost everyone finds eastward travel harder, and there is a real reason.
The human circadian clock, left to itself, runs slightly longer than twenty-four hours for most people. That means delaying your schedule — going to bed and waking later — runs with the natural drift and is relatively easy. Advancing it — going to bed and waking earlier — runs against the drift and is harder.
Flying west means your day gets longer and you need to stay up later. Natural direction. Easier.
Flying east means your day gets shorter and you need to sleep earlier than your body wants. Against the drift. Harder, and it is why a London-to-Tokyo trip feels so much worse than Tokyo-to-London.
How fast you can actually adjust
A commonly cited rule of thumb is about one time zone per day travelling west, and rather less than that travelling east — perhaps two-thirds of a zone per day. Individual variation is wide.
The practical implication is worth sitting with. Cross eight zones eastward and full natural adjustment takes well over a week. If your trip is five days, you will never fully adjust — which changes the strategy entirely, and is the reason the last section of this guide exists.
Shifting before you fly
The most effective thing you can do happens before you leave. Shifting even part of the way in advance takes a meaningful bite out of the arrival problem.
Three days out, start moving your sleep and wake times by an hour a day in the direction you are travelling — earlier for eastward, later for westward. Move meal times with it, since food timing has a modest influence on peripheral clocks. Pair it with light: bright light on waking if you are shifting earlier, bright light in the evening if you are shifting later.
Three days at an hour a day gets you three zones closer before you board. For a five- or six-zone trip, that is the difference between a rough first day and a ruined first week.
On the flight
Less happens here than people think, and the main thing is a decision rather than a technique.
Change your watch to destination time when you board, and start behaving as though you are already there. If it is night at your destination, try to sleep even if you are not tired. If it is daytime there, stay awake even if you are.
Beyond that: drink water because cabin air is extremely dry and dehydration makes everything feel worse; skip the alcohol because it fragments the sleep you are trying to get and worsens dehydration; and treat the in-flight meal schedule as optional, since it is set for the airline's convenience rather than your circadian needs.
An eye mask and earplugs are worth more than any supplement on this list.
The part that does the work: light timing
This is the section that separates useful jet lag advice from vague jet lag advice.
Light does not simply "help". It shifts your clock in a specific direction depending on when it arrives relative to your core body temperature minimum — which sits roughly two hours before your normal wake time at home.
- Light in the hours after your temperature minimum shifts your clock earlier (a phase advance). This is what you want when flying east.
- Light in the hours before your temperature minimum shifts your clock later (a phase delay). This is what you want when flying west.
Get this backwards and you actively push your clock the wrong way, which is why some people find their jet lag mysteriously worsening on day two.
Flying east: seek bright morning light at your destination, and avoid bright light in the local evening. Sunglasses on the way home from an early flight.
Flying west: seek bright light in the local late afternoon and early evening, and avoid it in the early local morning until you have adjusted a few days.
One important exception: crossing more than about eight zones eastward, your temperature minimum can land in local afternoon, and following the simple rule can shift you the wrong way round. For very long eastward trips, many people find it easier to treat it as a westward shift and go the long way round the clock. If you make trips like this regularly, a jet lag calculator that computes your specific light windows is worth the effort.
The first 48 hours
- Get outside as soon as you can, if the direction is rightOutdoor light is many times brighter than anything indoors and does most of the work. Check the direction rule first.
- Stay up until a plausible local bedtimeNot necessarily your usual time — 9pm is fine on the first night. Going to bed at 4pm because you are exhausted guarantees a 2am wake and a worse day two.
- Take a short nap if you must, and cap itTwenty to thirty minutes, before mid-afternoon. A three-hour nap on arrival removes the sleep pressure you need for the first night. Use the nap timer so it ends on time.
- Eat on local timeMeal timing influences peripheral clocks. Eating breakfast at local breakfast time is a small but genuine signal.
- MoveLight exercise, especially outdoors, helps alertness and reinforces the daytime signal. A walk is enough.
- Set an alarm for local morning and get up to itSleeping in on day one is the most common way people extend jet lag by several days. Set the alarm before you go to bed, with the maths challenge on if you know you will switch it off in your sleep.
Melatonin, caffeine and sleep aids
Melatonin has reasonable evidence for jet lag, but it is a timing signal rather than a sleeping pill and the dose matters less than when you take it. Low doses — well below what is typically sold — taken in the early evening at your destination are generally what has been studied for eastward travel. Taken at the wrong time it can shift you the wrong way. Availability and regulation vary considerably by country, and it interacts with some medications, so talk to a pharmacist or doctor rather than guessing.
Caffeine is useful for getting through the first local afternoon, and counterproductive after about midday local time when you are trying to sleep at a new hour.
Alcohol is the most reliably counterproductive thing available. It brings sleep on faster and makes the second half of the night worse, which is exactly the part you need.
Prescription sleep aids are sometimes appropriate for long-haul travel and are a conversation with a doctor, not something to improvise. This article is general information, not medical advice.
Short trips: do not adjust at all
If you are away for three days or fewer, deliberately not adjusting is often the better strategy.
Adjusting takes days you do not have, and then you have to readjust when you get home — so you spend the whole trip in transition and arrive back worse off. Instead, stay as close to home time as your commitments allow: schedule meetings during hours that fall in your home daytime where possible, keep meals on home time, and use a short nap and well-timed caffeine to cover the parts that do not fit.
It is not pleasant, but for a two-day trip it usually beats two half-adjustments back to back.
The short version
Shift an hour a day for three days before you leave. Change your watch when you board and behave as though you have arrived. On the ground, get bright morning light going east and late-afternoon light going west, and avoid it at the opposite end. Cap naps at thirty minutes, eat on local time, and get up to an alarm on the first local morning rather than sleeping in. For trips of three days or fewer, do not adjust at all.
Work out your first local bedtime with the bedtime calculator, then set the alarm for local morning before you fall asleep.