How to Beat Jet Lag: Science-Backed Tips for UK Travellers

Jet lag is what happens when your internal clock still thinks it's 3am in London while you're trying to function at lunchtime in New York, and no amount of willpower fixes that quickly. The science of beating it is well understood though: shift your schedule before you fly, use light as your main lever after you land, and protect your sleep on the plane. Follow that plan and a five-time-zone trip stops feeling like a week of brain fog.

What Jet Lag Actually Is

Your body runs on a master clock - the suprachiasmatic nucleus, a cluster of nerve cells in the hypothalamus - that sets the timing for sleep, digestion, temperature and hormones. When you fly across time zones, that clock doesn't move with you. It keeps firing on home time, so your body gets conflicting signals: the sun says morning, your gut says midnight. The NHS describes jet lag as the disruption of your body clock caused by crossing time zones.

Here's the number that matters: your clock re-syncs at roughly one to one and a half time zones per day. London to New York crosses five zones, so expect four to six days for a full reset. London to Bangkok is seven ahead, and Sydney sits around ten ahead in summer. That's why long-haul eastbound trips feel brutal while short hops west feel almost painless.

Why Eastbound Flights Hit Harder

The human circadian clock runs on a natural period of about 24.2 hours - slightly longer than a day. Because it runs long, it is far easier to push it later than to push it earlier. Flying west delays your clock, which your biology happily goes along with. Flying east means advancing it, which fights your natural rhythm.

That's why a New York to London red-eye, landing at 7am UK time when your body thinks it's 2am, leaves you hollow and disoriented, and why many travellers crash harder on day two or three than on day one. Expect eastbound recovery to take longer, and plan for it.

Before You Fly: Start Shifting Early

The NHS advice is to adjust your sleep routine to the destination time zone before you travel, and to get plenty of rest before you leave. Flying tired guarantees a much worse landing.

The practical version: for eastbound trips, shift bedtime and wake time 30 to 60 minutes earlier for two or three nights before departure. For westbound trips, shift them later instead. Move meals with your sleep too, because meal timing is a secondary clock cue, and set your watch to destination time the moment you board.

On the Flight: Protect Whatever Sleep You Can

The golden rule is to live on destination time from the moment you sit down: sleep when it's night where you're going, and stay awake when it's daytime there, even with the cabin lights off.

Sleeping in economy is never great, but the right kit helps. A memory foam travel pillow like the Cabeau Evolution S3 straps to the seat and stops your head dropping forward, while the FLOWZOOM inflatable pillow packs down tiny for carry-on travellers. A proper silk sleep mask such as the OLESILK sleep mask blocks the cabin lights that suppress melatonin, and a pair of Loop Quiet 2 earplugs takes the edge off engine noise.

For more options, see our roundups of the best travel pillows UK, best sleep masks UK and best earplugs for sleeping UK.

One thing to skip entirely: alcohol. A glass of wine might knock you out, but it fragments sleep and worsens the circadian disruption. Water, and caffeine timed to destination daytime, are better tools.

After Landing: Light Is the Master Switch

Light is the strongest cue your master clock responds to, so use it deliberately. After an eastbound flight, get outside within the first hour of waking - morning light advances your clock toward the new zone. After a westbound flight, do the opposite: seek bright light in the late afternoon and evening to delay it.

Keep the evenings dim after eastbound travel. If you're struggling to wake on the new schedule, a Lumie Bodyclock Glow 150 sunrise alarm can fake a natural dawn for the first few mornings. Keep naps to 20 or 30 minutes, before 2pm local time. A two-hour nap at 5pm will undo a full day of resetting.

Melatonin: The Treatment With Real Evidence

Of all the remedies sold for jet lag, melatonin is the one with genuine randomised-trial support. The Cochrane review of randomised trials concluded that melatonin is effective at preventing or reducing jet lag, and recommended it for adults crossing five or more time zones, particularly eastbound.

In the UK, melatonin is licensed specifically for jet lag: a 3mg tablet taken at your new local bedtime, once a day for up to five nights, per NHS guidance. It is not a sleeping pill - it signals to your clock that it's night.

Do not give it to children, and check with a pharmacist or GP if you have health conditions or take other medicines. Our guide to melatonin supplements UK covers the practical details.

How Long Until You Feel Normal?

Set your expectations before you fly. At one to one and a half zones a day, a US trip takes four to six days, and most people feel 80% better within two or three. The mistake is judging yourself against day-one jet lag and concluding nothing worked. The reset is cumulative - each day of correct light timing and sleep scheduling moves you closer.

If you're flying somewhere for a short break, that reset may barely begin before you're home again. Treat the flight home the same way and accept a few groggy days. Persistent sleepiness that doesn't lift after a week or two is worth mentioning to your GP, because it can point to something other than travel. See our guide to sleep debt recovery for more.

Jet lag is a biology problem, not a willpower problem. Work with your clock - morning light, dim evenings, melatonin at the right time - and the worst of it usually passes within a couple of days. For more sleep guides, visit SleepReview.

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