Jet Lag - symptoms, causes and treatment

Jet lag — medically known as desynchronosis — occurs when your body's internal clock (circadian rhythm) is out of sync with the local time at your destination. It's most common after crossing three or more time zones, especially when travelling eastward. Common symptoms include: Difficulty falling or staying asleep at local bedtime Daytime fatigue and sleepiness Poor concentration or "brain fog" Irritability and low mood Digestive upset Most people recover within a few days, but the right treatment can significantly shorten this window.

Melatonin is a naturally occurring hormone that signals to your brain when it's time to sleep. When taken at the correct time, prescription melatonin can help shift your circadian rhythm to align with a new time zone — reducing jet lag symptoms and helping you feel restored sooner. Unlike sleeping tablets, melatonin does not force sleep. Instead, it gently resets your body clock, making it easier to fall asleep and wake at the appropriate local times.

The effectiveness of melatonin depends on getting the timing right. The correct dose and schedule vary based on your direction of travel. Travel Direction Typical Dose When to Take Duration Eastward (e.g., UK → Asia) 2–5mg 30–60 mins before local bedtime (10pm–11pm) 3–5 days Westward (e.g., UK → US) 0.5–3mg Evening after arrival, or 30 mins before local bedtime 2–3 days Pre-travel adjustment 0.5–3mg Evening before departure, shifting gradually towards destination time 2–3 days before travel Your Access Doctor prescriber will provide a personalised dosing plan based on your itinerary and medical history.

Melatonin for jet lag is licensed for adults aged 18 and over. It is generally well tolerated, but may not be suitable for everyone. You should discuss your circumstances with a prescriber if you: Are pregnant or breastfeeding Have liver disease or autoimmune conditions Take anticoagulants (such as warfarin) or anticonvulsants Have a history of depression or other mental health conditions

Do not drive or operate machinery within several hours of taking melatonin Avoid alcohol while taking melatonin — it can increase drowsiness and disrupt sleep quality Treatment should not exceed five days for jet lag Melatonin is a prescription-only medicine in the UK — it is not available over the counter

Jet lag usually resolves on its own. However, seek urgent medical advice if you experience: Chest pain or palpitations during or after your flight (possible DVT or pulmonary embolism) Sudden shortness of breath or leg swelling Extreme confusion that goes beyond normal travel fatigue If sleep disturbance or fatigue persists for more than two weeks after returning home, speak to your GP.

Can I buy melatonin over the counter in the UK for jet lag? No. Melatonin is a prescription-only medicine in the UK. You must obtain it through a regulated prescriber, such as Access Doctor's online consultation service, or your GP. What is the correct melatonin dose for jet lag? The standard dose for jet lag in adults is 3mg of immediate-release melatonin, taken once daily. However, doses may vary depending on your direction of travel and individual circumstances. Your prescriber will provide specific guidance. Does melatonin make you sleep immediately? No. Melatonin is not a sedative. It works by adjusting your body's internal clock, helping your brain recognise when it is night-time in the new time zone. Is it safe to take melatonin during pregnancy or while breastfeeding? Melatonin is not routinely recommended during pregnancy or breastfeeding due to limited safety data. You must disclose this during your consultation so your prescriber can advise appropriately. Can I drink alcohol while taking melatonin? No. Alcohol can interfere with sleep quality and may increase the sedative effects of melatonin. Avoid alcohol while taking melatonin and during the first few days of travel. How long does melatonin take to work? Melatonin typically begins working within 30–60 minutes. Most people notice improvement in jet lag symptoms within 1–2 days, with full benefits after 3–5 days of consistent use at the correct time. What happens if I take melatonin at the wrong time? Taking melatonin at the wrong time can shift your circadian rhythm in the opposite direction, potentially making jet lag worse. Always follow your prescriber's timing guidance. Does the direction of travel affect how I should take melatonin? Yes. Eastward travel generally requires a higher dose taken in the evening to advance your sleep phase. Westward travel may require a lower dose taken on arrival. Your prescriber will advise based on your itinerary.

Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews. 2002. NHS. Melatonin — How and when to take it. NHS. Jet lag. British Airline Pilots' Association (BALPA). Managing jet lag: guidance for flight crew and travellers. 2024. British National Formulary (BNF). Melatonin: indications and dosing.