Chelsea Green Pharmacy
London is one of the world’s busiest travel hubs. Whether you are flying long-haul for business, heading off on holiday, or returning from the other side of the world, jet lag is something most frequent travellers will know all too well. The disrupted sleep, the midday exhaustion, the 3am alertness and the general feeling of being slightly out of step with the world around you can linger for days and, for some people, significantly affect how well they function after a flight.
Understanding what jet lag actually is, why it happens, and how to manage it properly can make a real difference to how quickly you recover. Read on for everything you need to know.
What Is Jet Lag and Why Does It Happen?
Jet lag is a temporary sleep disorder caused by a mismatch between your internal body clock (known as your circadian rhythm) and the local time at your destination. Your circadian rhythm regulates nearly every function in the body, including sleep and wakefulness, hunger, digestion, hormone release, and body temperature. It is anchored primarily by light exposure, and it runs on a roughly 24-hour cycle.
When you fly across multiple time zones, your body clock does not automatically reset to match the new environment. It continues running on the rhythm of where you came from. The more time zones you cross, the greater the mismatch and the more pronounced the symptoms tend to be.
Direction also matters. Travelling east is generally harder than travelling west. When heading east, you are required to advance your body clock, falling asleep earlier than it feels natural. Flying west asks you to delay it, which tends to be more achievable because the human body clock naturally runs slightly longer than 24 hours.
Common Jet Lag Symptoms
Jet lag presents differently in different people, but the most frequently reported symptoms include:
- Difficulty falling or staying asleep at the correct local time
- Excessive daytime sleepiness or fatigue
- Difficulty concentrating or a feeling of mental fog
- Irritability or low mood
- Gastrointestinal disturbance, including nausea, constipation, or diarrhoea
- General malaise or a sense of feeling unwell
- Reduced physical coordination or performance
For most people, symptoms resolve within a few days as the body adjusts. However, for frequent long-haul travellers, or those who need to perform at their best immediately after arrival, this is far from ideal.
| Time Zones Crossed | Typical Recovery Time | Severity |
|---|---|---|
| 1 to 2 | Less than 1 day | Mild, often barely noticeable |
| 3 to 5 | 2 to 3 days | Moderate, noticeable disruption |
| 6 to 9 | 4 to 6 days | Significant, affects daily functioning |
| 10 or more | Up to 1 week or longer | Severe, can affect health and performance |
Who Is Most Affected?
Jet lag affects people differently depending on a range of factors. Those who tend to experience it more severely include:
- Older adults, whose circadian rhythms are generally less adaptable
- People with existing sleep disorders
- Frequent flyers who do not give their body clock adequate time to reset between trips
- Those travelling eastward across six or more time zones
- Travellers who are already sleep-deprived before departure
Jet lag is a recognised sleep condition and not simply tiredness from a long flight. The physical fatigue of travel adds to it, but they are separate issues with different causes.
How to Prevent Jet Lag Before You Fly
The most effective approach to jet lag begins before you board. A few practical steps can reduce how severely it affects you:
- Adjust your sleep schedule gradually in the days before departure, shifting bedtime earlier or later depending on your destination’s time zone
- Stay well hydrated in the 24 to 48 hours before flying and throughout the flight, as dehydration worsens symptoms
- Avoid alcohol and caffeine on the flight, both of which disrupt sleep quality
- Set your watch to your destination’s time as soon as you board and begin mentally orienting to it
- Choose flight times that allow you to arrive in daylight if possible, as light exposure is the most powerful reset signal for the body clock
Planning a long-haul trip from London? Our travel clinic at 6 Elystan Street, Chelsea, London, SW3 3NS can help you prepare fully, from vaccinations and antimalarials to advice on managing jet lag and staying well throughout your journey.
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Treatment: Managing Jet Lag After Arrival
Once you have landed, the priority is helping your body clock recalibrate as quickly as possible. The following strategies are the most well-supported:
Light Exposure
Natural daylight is the most powerful tool available. Get outside during local daylight hours as soon as possible after arriving. Conversely, avoid bright light in the late evening if you have travelled east and are trying to sleep earlier than usual.
Melatonin
Melatonin is a hormone your brain naturally produces in response to darkness to signal that it is time to sleep. Short-term use of low-dose melatonin supplements can support the re-synchronisation of the body clock, particularly when travelling east. It is available over the counter in some countries and on prescription in others. Speak to our team for guidance on whether it is appropriate for your situation.
Sleep Hygiene at Your Destination
Resist the urge to nap for long periods during the day, as this can delay adjustment. If you must nap, keep it to 20 minutes maximum. Use blackout curtains or an eye mask at night and avoid screens in the hour before bed.
Staying Active
Light exercise during the day, a walk outside or a swim, can help accelerate circadian adjustment. Avoid intense exercise close to local bedtime, as this may interfere with sleep onset.
Frequently Asked Questions
How many days does jet lag usually last?
For most travellers, jet lag resolves within two to five days. A useful rule of thumb is one day of recovery per time zone crossed, though this varies considerably between individuals. Eastward travel typically requires longer to adjust than westward travel.
Does melatonin actually help with jet lag?
Evidence suggests that melatonin can be effective for reducing jet lag symptoms, particularly when travelling across five or more time zones in an eastward direction. Timing matters significantly. Taking it at the wrong time can actually worsen symptoms, so it is worth discussing use with a healthcare professional before relying on it.
Can jet lag affect your health beyond tiredness?
Repeated or severe disruption to the circadian rhythm has been associated in research with broader effects on metabolic health, immune function, and mood regulation. For occasional travellers, jet lag is a temporary inconvenience. For very frequent long-haul travellers, managing it properly is a sensible health priority rather than simply a comfort issue.
Is jet lag the same as travel fatigue?
No. Travel fatigue is physical exhaustion from the journey itself, the sitting, the disrupted meals, the dry cabin air. Jet lag is specifically a circadian rhythm disorder caused by crossing time zones. Both can occur simultaneously, which is why people sometimes feel worse after a long-haul flight than the time zone difference alone would explain.
Can children get jet lag?
Yes, children experience jet lag too, and it can be particularly disruptive for younger ones whose sleep routines are more rigid. The same principles apply: light exposure, gradual adjustment, and maintaining consistent sleep cues at the destination all help. Most children adapt relatively quickly once they are back in a regular routine.
What else should I consider before a long-haul trip from London?
Jet lag is just one aspect of travel health. Depending on your destination, you may also need to consider vaccinations, antimalarial medication, advice on altitude sickness, or guidance on travelling with existing health conditions or regular medications. Our Chelsea travel clinic can provide a full pre-travel health consultation to cover everything relevant to your trip.
Travel Health Support in Chelsea
Jet lag is something most travellers simply put up with, but with the right preparation and the right advice, its impact can be significantly reduced. Whether you are planning a long-haul business trip or a once-in-a-lifetime holiday, our team at our Chelsea travel clinic is here to help you travel well and come back feeling your best.
Contact us or book an appointment at our clinic at 6 Elystan Street, Chelsea, London, SW3 3NS.
