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Dr. Chrysoula I. Liakou MD, PhD
- Treated online: Yes. A plan built around your flights, and advice on whether a medicine fits.
- Who gets it: anyone crossing at least 2 time zones; flying east is usually harder than flying west.
- How long it lasts: the body clock shifts about 1 hour a day after flying east and about 1.5 hours a day after flying west.
- What helps most: daylight at the right time of day, and moving meals and sleep to local time as soon as you land.
- Emergency: call 112 for chest pain or sudden breathlessness after a long flight; a painful, swollen leg needs urgent medical advice.
Do not book a video appointment for chest pain, sudden breathlessness, coughing up blood, a painful, swollen calf after a long flight, confusion or a sudden severe headache. These can signal a blood clot or another emergency: call 112.
Can an online doctor help with jet lag?
Yes. Jet lag is recognised from your flights and your symptoms, and what helps is a plan for daylight, sleep and meals, sometimes with a medicine. All of that works by video. The doctor tailors the plan to your direction of travel and your schedule, and checks that nothing else, such as a blood clot after a long flight or an infection picked up on the trip, explains how you feel.
How an online consultation helps with jet lag
- A plan built on your flights: Departure and arrival times, the number of time zones and the direction decide when you should seek daylight and when you should avoid it.
- Your regular medicines timed: Medicines taken at set times, such as insulin or the contraceptive pill, need a plan across time zones, and the doctor sets one with you.
- Medicine only when it helps: The doctor explains what the evidence says about melatonin and sleep aids, and whether either fits your trip and your health.
- Something else ruled out: Exhaustion that does not lift after a week, a fever or a swollen leg are not jet lag, and the doctor checks for them.
What the doctor checks in an online jet lag consultation
The consultation follows a fixed order, and the emergency signs come first. The doctor asks about:
- Clot warning signs: a painful, swollen calf, chest pain or breathlessness after a long journey.
- Your flights: the direction, the number of time zones, and when you depart and arrive.
- The trip: how long you will stay, and whether you need to be alert at set times, for work or for driving.
- Your sleep: how you usually sleep, and any sleep problems before the trip.
- Your medicines: anything taken at fixed times, sleep aids you have used, and medicines that cause drowsiness.
Before the call, have your flight times to hand, in both local time zones, and a list of the medicines you take and when.
What is jet lag?
Jet lag is a temporary sleep problem caused by crossing time zones faster than the body clock can follow. The body clock, which times sleep, hunger, alertness and digestion, stays on home time for days, while daylight and the clock on the wall have moved on. Doctors use the term when travel crosses at least 2 time zones and causes broken sleep or daytime sleepiness.
Flying east is usually harder than flying west. The body clock runs slightly longer than 24 hours, so stretching the day, as happens when you fly west, is easier than shortening it. Long flights add their own tiredness, from dry cabin air, cramped seats and broken sleep, which makes jet lag feel worse in the first day or two.
The forbidden zone for sleep
In the 2 to 3 hours before your usual bedtime, the body clock sends a strong signal to stay awake, and falling asleep is hardest. Sleep researchers call this window the forbidden zone for sleep. After flying east, the local bedtime falls earlier on your body clock, often inside that window, which is why lying awake at the first local bedtimes is so common. As the body clock shifts, the window moves with it.
Jet lag symptoms: what does it feel like?
Symptoms usually start within a day or two of arrival:
- difficulty falling asleep at bedtime, or waking in the early hours
- sleepiness and tiredness during the day
- poor concentration and memory
- indigestion, nausea, constipation or a change in appetite
- feeling generally unwell, or mildly anxious
A fever, a cough, diarrhoea or a rash during or after a trip is not jet lag, even if you also feel exhausted. Those symptoms point to an infection picked up while travelling and deserve a doctor’s assessment. Chest pain or sudden breathlessness after a long flight is not jet lag either: it can mean a blood clot in the lungs, and needs 112.
How long does jet lag last?
On average, the body clock catches up by about 1 hour a day after flying east and about 1.5 hours a day after flying west. That gives a rough guide to recovery time:
Swipe sideways to compare →
| Time zones crossed | Flying east | Flying west |
|---|---|---|
| 3 | About 3 days | About 2 days |
| 6 | About 6 days | About 4 days |
| 9 | About 9 days | About 6 days |
Good timing of daylight can shorten this, and poor timing can lengthen it. Tiredness that is still heavy after a week, or comes with other symptoms, is worth a doctor’s review.
Why do I get bad jet lag?
How bad jet lag gets depends mostly on how many time zones you cross and in which direction, and on whether you see daylight and keep local mealtimes and bedtimes at the destination. Other things make it worse:
- Light at the wrong time: bright light in the morning shifts the clock earlier, and in the evening later, so light at the wrong time of day slows recovery.
- Alcohol: it may help you fall asleep, but it breaks up sleep later in the night.
- Losing fluid: not drinking enough on a long flight can make the physical symptoms worse.
- Your genes and medicines: people differ in how fast their body clock adjusts, and some medicines affect sleep.
Why is jet lag worse coming home?
Often because the flight home is the eastward one. Trips from Europe to the Americas end with a flight east, and the body clock adjusts by about 1 hour a day after flying east, against about 1.5 hours a day after flying west. The US east coast is 5 hours behind the UK, so after flying home to the UK expect about 5 days to adjust fully, against 3 to 4 days after the flight out. After a trip to Asia it is the other way round: the outward flight east is the harder one.
How to beat jet lag: daylight, sleep and caffeine
Before you fly
Rest well in the days before the trip. For a few nights, move your bedtime and waking time an hour or so towards the time at your destination.
On the plane
Drink water, because losing fluid can make the physical symptoms of jet lag worse, and walk around the cabin and stretch your legs. Try to sleep if it is night at your destination, with an eye mask and earplugs, and go easy on caffeine and alcohol, which both make jet lag worse.
When you arrive
Switch to local time straight away: eat at local mealtimes, go to bed at a local bedtime and set an alarm so you do not oversleep. Daylight is the strongest signal for the body clock, and its timing depends on your direction of travel:
Swipe sideways to compare →
| Direction | Seek bright light | Avoid bright light |
|---|---|---|
| Flying east | In the morning | In the evening |
| Flying west | In the evening | Early in the morning |
Use caffeine in the local morning and early afternoon, and stop about 6 hours before bed. If you must nap, keep it to about 20 minutes; long naps make night-time sleep harder.
Short trips
For a stay of two days or less, it is usually better not to adjust at all: keep your sleep and meals on home time where you can, so you do not have to change your body clock twice.
Which jet lag treatment might the doctor recommend?
Most jet lag responds to daylight and routine alone. This is the framework the doctors use, in line with NHS and CDC guidance.
Swipe sideways to compare →
| What you have | Likely first step | Suitable for online care? | When in-person care is needed |
|---|---|---|---|
| A trip across 2 to 4 time zones | Daylight timing, local mealtimes and bedtimes | Yes | Not usually needed |
| Long-haul travel east, or a demanding schedule on arrival | A detailed light and sleep plan; discussion of melatonin | Yes | Not usually needed |
| Medicines taken at set times, such as insulin | A dose-timing plan for the journey | Yes | If your condition needs monitoring |
| Exhaustion still heavy after a week back home | Assessment for other causes | Yes, first assessment | Blood tests in person if needed |
| A swollen, painful leg, chest pain or breathlessness after a flight | Emergency assessment for a clot | No | Call 112 now |
Long-haul flight coming up? A doctor can build your jet lag plan in one consultation.
See available times →Treatment options for jet lag
What you can do yourself
- Switch to local time for meals and sleep as soon as you land.
- Get outside in daylight at the right time of day for your direction of travel.
- Use caffeine in the local morning, stop about 6 hours before bed, and keep naps to about 20 minutes.
- Avoid alcohol as a sleep aid: it makes jet lag worse, not better.
Prescription treatment
A prescription is never issued without a consultation. Medicines are not usually needed for jet lag. Melatonin, the hormone the body releases in the evening, can shift the body clock when it is taken at the right time, but the evidence for jet lag is mixed and the NHS does not recommend it for this use. Melatonin is licensed for the short-term treatment of jet lag in adults: it is taken at the usual bedtime at the destination, never before 8pm or after 4am local time, without alcohol, and not before driving. The doctor discusses whether it makes sense for your trip and, if so, how to time it. If the doctor prescribes, use the prescription at a pharmacy near you.
Sleeping tablets that can cause dependence are controlled medicines and are never prescribed online. Drowsy antihistamines are not a good substitute: they can dull thinking the next day and raise the risk of falls.
What does not help
Long daytime sleeps and alcohol make jet lag worse, and so does staying indoors in dim light for the first days of the trip.
Special situations
Insulin and other medicines taken at set times
If you take insulin or another medicine at fixed times, plan how to time it across the time zones with a doctor before you fly, and carry it in your hand luggage. Run your medicines through the medication checker before you go.
The contraceptive pill
Keep to the same number of hours between pills rather than the same clock time, and check the missed-pill rules in the leaflet if the gap grows longer than usual.
Business trips and frequent flyers
On short trips, stay on home time where possible and schedule important meetings for the hours that would be daytime at home. Frequent long-haul flyers who never seem to recover can discuss a longer-term sleep plan with the doctor.
Long flights and blood clots
Journeys of more than 4 hours raise the risk of a clot in the leg, especially after recent surgery, in pregnancy or with oestrogen-containing medicines. Walk around when you can, drink water and avoid alcohol. A painful, swollen calf after a flight needs urgent medical advice, and breathlessness or chest pain needs 112.
Children
Mobi Doctor consultations are for adults aged 18 and over. A child who is unwell needs a paediatrician or a local doctor in person, and emergency signs in a child mean 112.
When jet lag is treated online, and when you need in-person care
Treated online: jet lag plans for upcoming flights, advice on melatonin, timing of regular medicines across time zones, and first assessment of tiredness that will not lift.
In-person care: a painful, swollen leg, chest pain or breathlessness after a flight, a fever after travel that needs tests, and confusion or a severe headache.
When to get in-person care
Call 112 or go to an emergency department now for:
- chest pain, sudden breathlessness or coughing up blood after a long journey
- confusion, a sudden severe headache, or weakness on one side
- fainting, or feeling very unwell with a high fever after travel
Get medical advice the same day for:
- a painful, swollen calf or thigh after a long flight, car or train journey
- a fever, diarrhoea or a rash during or after a trip
- missed or mistimed doses of an essential medicine, such as insulin
How Mobi Doctor works
- Book a time that suits you: daily 7am–11pm CEST. You can see a doctor over video, usually within 15 minutes. No subscription, and the exact price is shown before you pay.
- Speak to a licensed doctor about your flights: share the flight times in both time zones, how long you will stay, and the medicines you take at set times.
- Leave with a plan: what to do, what to take and for how long, and which signs mean you should be seen in person. If the doctor prescribes, use the prescription at a pharmacy near you.
No sign-up needed
Not sure it’s jet lag? Tick every symptom you have to see each condition page that mentions it. It finds the right page, not a diagnosis: a doctor gives you that on a video call.
Tap the body — an area or a point — to browse symptoms anywhere
Similar symptoms, different condition? Insomnia can start the same way. Compare them, or look up any other symptom in the full symptom checker.
Frequently asked questions about jet lag
How long does jet lag last?
On average, jet lag lifts as the body clock catches up by about 1 hour a day after flying east and about 1.5 hours a day after flying west. After crossing 6 time zones, that means roughly 6 days going east and 4 days going west, less if you time daylight well.
Is jet lag worse flying east or west?
Jet lag is usually harder after flying east. The body clock naturally runs slightly longer than 24 hours, so it adapts more easily to a longer day, which is what flying west gives you, than to a shorter one.
What helps jet lag fastest?
To shake off jet lag, switch to local time as soon as you land, get daylight at the right time of day for your direction of travel, use caffeine only in the local morning and early afternoon, and keep naps to about 20 minutes.
Can jet lag be prevented?
Partly. Shift bedtime and meals by an hour a day towards destination time for 2 or 3 days before a long eastward trip, choose a flight that lands in the evening, set your watch to local time at take-off, sleep or stay awake on the plane according to destination time, avoid alcohol in the air, and on arrival get morning daylight after flying east and late-afternoon daylight after flying west. Jet lag across 6 or more time zones cannot be prevented entirely.
Does melatonin help jet lag?
Melatonin can shift the body clock when it is taken at the right time, and it is licensed for short-term treatment of jet lag in adults, taken at bedtime at the destination. The evidence is mixed, and the NHS does not recommend it for this use. A doctor can tell you whether it makes sense for your trip and how to time it.
Can an online doctor prescribe something for jet lag?
Medicines are not usually needed for jet lag. After a video consultation the doctor can advise on melatonin and prescribe it when it is appropriate. Sleeping tablets that can cause dependence are controlled medicines and are never prescribed online.
Should I sleep on the plane or nap when I arrive?
To limit jet lag, sleep on the plane if it is night at your destination, using an eye mask and earplugs, and stay awake if it is daytime there. After you land, avoid long naps: a nap of about 20 minutes refreshes without making night-time sleep harder.
Why is jet lag worse coming home?
Jet lag is often worse coming home because the flight home is the eastward one, and the body clock adjusts more slowly after flying east, by about 1 hour a day. Flying home to the UK from the US east coast crosses 5 time zones, so it can take about 5 days to feel fully adjusted.
What is the forbidden zone for sleep?
In jet lag terms, the forbidden zone is the 2 to 3 hours before your usual bedtime, when the body clock pushes hardest to keep you awake. After flying east, the local bedtime can fall inside it, which is why falling asleep at first is so hard.
Is it jet lag or something else?
Jet lag is tiredness and broken sleep that start within a day of crossing time zones and improve each day, with no fever. Travel fatigue from a long journey lifts after one good night even without a time-zone change; a fever, diarrhoea or a rash after travel points to an infection; tiredness still heavy after a week may be anaemia, thyroid disease, depression or sleep apnoea; and a swollen painful calf or breathlessness after a long flight suggests a blood clot and needs urgent care.
Does drinking water help jet lag?
It helps with the physical symptoms. Losing fluid on a long flight can make jet lag feel worse, so drink water during the flight and limit alcohol and caffeine. Water does not reset the body clock: daylight at the right time does.
Can jet lag cause a fever or chest pain?
No. Jet lag causes neither; a fever during or after a trip points to an infection and needs a doctor. Chest pain or sudden breathlessness after a long flight can mean a blood clot in the lungs: call 112.
When should I see a doctor about jet lag?
See a doctor if jet lag tiredness is still heavy after a week, or if you have a fever, diarrhoea or a rash after travel. A painful, swollen leg after a flight needs urgent medical advice, and chest pain or breathlessness needs 112.
- Jet lag, NHS, National Health Service (UK), reviewed 31 May 2023.
- Jet lag disorder, CDC Yellow Book 2026, Centers for Disease Control and Prevention, 23 April 2025.
- Deep vein thrombosis (DVT), NHS, National Health Service (UK), reviewed 30 April 2026.
- Melatonin hard capsules: summary of product characteristics, electronic medicines compendium (emc), revised 11 June 2025.
- The forbidden zone for sleep is more robust in adolescents compared to adults, Monterastelli AJ et al., Frontiers in Sleep, 2024.
This page is for information only and is not a substitute for a medical consultation. Guideline links are provided for transparency; treatment decisions are made with your doctor.
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