Jet lag is an unavoidable challenge for anyone travelling across time zones. Whether it’s a business trip to New York, a family holiday in Australia, or a weekend break in Dubai, your body’s internal clock — known as the circadian rhythm — struggles to adapt instantly. The result? Disrupted sleep, fatigue, and impaired daily performance.
In this guide, we’ll break down how jet lag affects the body, why it disrupts sleep, and the safe over-the-counter (OTC) fixes available in the UK to help you adjust faster.
What Is Jet Lag?
Jet lag is a temporary sleep disorder caused by rapid travel across multiple time zones. Your internal clock is synchronised with your home time zone, but when you arrive at your destination, local time is different. This mismatch throws off your sleep-wake cycle, hormone production, and digestion.
It’s most noticeable when travelling east (e.g., London to Bangkok) because your body has to “shorten” the day, which is more difficult than lengthening it.
Symptoms of Jet Lag
- Difficulty falling asleep at night or waking up too early
- Daytime fatigue and lack of energy
- Poor concentration and brain fog
- Mood swings or irritability
- Stomach discomfort or loss of appetite
These symptoms usually last 2–7 days, depending on the number of time zones crossed and individual factors like age, health, and sleep habits.
Why Jet Lag Disrupts Sleep
Circadian rhythm misalignment
Your circadian rhythm is a 24-hour internal clock that regulates sleep, alertness, body temperature, and hormone release. Travelling to a different time zone causes a mismatch between your internal rhythm and local time.
Hormonal shifts
Melatonin, the sleep hormone, is released in response to darkness. Jet lag delays or advances this release, making it harder to sleep at the “right” time in your new location.
Light exposure differences
Natural light is the main cue for resetting your internal clock. Exposure to sunlight at the wrong time can worsen jet lag symptoms.
Lifestyle disruptions
Air travel often involves long periods of sitting, dehydration, and altered meal patterns — all of which can influence sleep quality.
Safe OTC Fixes for Jet Lag in the UK
Antihistamine-based sleep aids
These include products like Nytol (diphenhydramine) or Phenergan (promethazine), available from pharmacies without a prescription. They promote drowsiness and can help you fall asleep on local time.
- Best for: Short-term sleep onset issues.
- Dosage: Typically 25–50 mg taken 20–30 minutes before bedtime.
- Cautions: Morning grogginess and dry mouth; avoid driving after use. Not recommended for more than a few days in a row.
Herbal sleep remedies
Valerian root, passionflower, and chamomile teas or supplements are popular in the UK for relaxation. While evidence varies, they may help mild sleep disruption without the same hangover effect as sedating antihistamines.
- Best for: Mild cases or when you prefer a “natural” approach.
- Dosage: Varies; follow packaging instructions.
- Cautions: Can interact with other medications (e.g., sedatives, antidepressants).
Magnesium supplements
Magnesium supports muscle relaxation and nervous system balance, which may indirectly improve sleep quality.
- Best for: Relaxation and easing tension after long flights.
- Dosage: 200–400 mg in the evening.
- Cautions: High doses can cause digestive upset.
Melatonin — the special case
In the UK, melatonin is prescription-only for people over 55 with chronic insomnia, but it’s widely available OTC in other countries. Some UK travellers purchase it abroad.
- Best for: Resetting the sleep-wake cycle, especially when travelling east.
- Dosage: Commonly 0.5–3 mg taken 30–60 minutes before bedtime at the destination.
- Cautions: Possible headaches, vivid dreams, and morning grogginess. Always check legality when importing.
Caffeine timing
Caffeine isn’t a sleep aid, but strategic use in the morning can help combat daytime fatigue and signal to your body that it’s time to be awake. Avoid after midday to protect nighttime sleep.
Non-medication Strategies That Work Alongside OTC Fixes
Gradual adjustment before travel
Shift your bedtime and wake time by 30–60 minutes each day in the week before departure to match your destination’s time zone.
Controlled light exposure
Seek bright light in the morning if travelling east, and in the evening if travelling west. Avoid screens before bed to minimise blue light exposure.
Hydration and diet
Dehydration worsens fatigue. Drink water throughout your flight and avoid excessive alcohol or caffeine. Eat light, balanced meals to avoid digestive discomfort.
Movement during flight
Walking, stretching, and light in-seat exercises keep circulation healthy and reduce stiffness, making it easier to rest later.
Sleep environment control
Use earplugs, an eye mask, and a travel pillow to improve rest on planes and in hotels. Keep your room dark and cool.
When to Seek Medical Advice for Jet Lag
While jet lag is temporary, if you experience:
- Sleep problems lasting more than 2 weeks after travel
- Severe fatigue affecting your safety or job performance
- Worsening mood or mental health symptoms
- Suspicion of an underlying sleep disorder (e.g., sleep apnoea)
… then consult your GP or a sleep specialist.
FAQs
Can I take OTC sleep aids every night while travelling?
No. They are meant for short-term use — ideally just for the first few nights at your destination.
Is melatonin legal to bring into the UK?
Yes for personal use, but it’s prescription-only in the UK. If purchased abroad, declare it if questioned at customs.
What’s the fastest way to recover from jet lag?
Combine light exposure control, hydration, short naps (20–30 minutes), and a short course of OTC sleep aids if necessary.
Are herbal sleep aids as effective as medication?
They may work for mild cases but generally have less potent sedative effects than antihistamines or melatonin.
Does flying west cause less jet lag?
Usually yes — because your body clock finds it easier to lengthen the day than to shorten it.