Which is worse, flying east or west?

Flying east is usually harder, because you have to advance your clock and fall asleep earlier than your body wants. Flying west, where you stay up later, is generally easier to adjust to.

How long does jet lag last?

It’s temporary and usually improves within a few days. A common rule of thumb is that the body re-syncs at roughly one time zone per day, so more time zones means longer – but this is only an approximation and varies from person to person.

Should I take melatonin?

It may help, especially for eastward trips taken at destination bedtime, but timing and dose matter and it’s prescription-only in Singapore (and some authorities, like the NHS, don’t recommend it for jet lag). Ask a pharmacist or doctor rather than self-medicating.

I have diabetes and take insulin – anything special?

Yes. Crossing time zones shifts when your doses are due, which can be tricky with insulin and some other medicines. Speak to your doctor before travelling to plan dose timing, and keep medication in your carry-on.

Jet Lag Singapore | How to Prevent & Recover Faster

Q: What’s the single most useful thing I can do?

Get outdoor daylight at the right times at your destination and shift your sleep and meals to local time straight away. Light is the strongest signal for resetting your body clock.

Written & reviewed by the BestDoctors.sg editorial team · Last updated 2 Sep 2026 · General information, not medical advice

Quick answer. Jet lag is a temporary sleep and body-clock disruption that happens when you fly rapidly across several time zones, so your internal clock is still on “home time” while the world around you is on a new schedule. It usually settles on its own within a few days as your body adjusts, and you can shorten it by getting daylight at the right times, keeping to local sleep and meal times, and staying hydrated.

Breathless, wheezy, or living with a persistent cough?

Message our care team on WhatsApp. Tell us what’s going on and we’ll help you find the right sleep & respiratory doctor — free, with no obligation.

Chat with our care team on WhatsApp

Not sure who to see? Find the right specialist →

In a medical emergency, or for severe or sudden symptoms such as breathing difficulty, chest pain, fainting or stroke signs, call 995 immediately.

The single most useful thing: get outdoor daylight at the right times at your destination and shift your sleep and meals to local time straight away – light is the strongest signal for resetting your body clock.

What jet lag is

Jet lag is a temporary sleep and body-clock problem that appears after travelling quickly across several time zones. Your body runs on an internal clock – the circadian rhythm – which governs when you feel sleepy, alert and hungry across the day. When you fly a long distance in a short time, that clock stays set to your departure time while your destination is living on a different day and night. The result is a mismatch: your body says “sleep” when the new city says “morning”, and “wake up” when it says “night”.

Jet lag is common and settles on its own as the body catches up, but it can spoil the start of a trip – which matters for travellers passing through a busy hub like Singapore. It is worth separating it from ordinary travel fatigue: a cramped cabin, poor sleep and crowded airports leave anyone tired, even without crossing time zones, and that tiredness eases with rest. True jet lag is specifically the clash between your body clock and local time.

Symptoms to expect

Symptoms vary from person to person and from trip to trip, but the common ones include:

Disturbed sleep – difficulty falling or staying asleep at night, and feeling sleepy or drowsy during the day at your destination;
Tiredness and fatigue that lingers through the day;
Poor concentration and memory, and a general sense of not performing at your best;
Irritability or low mood;
Headaches;
Tummy upset or changes in appetite and bowel habit, since digestion is also tied to the body clock.

Symptoms are usually most noticeable soon after arrival and then ease as the days pass.

Why it happens

Your body clock is guided mainly by light, and by the hormone melatonin, which the body releases as darkness falls to signal that it is time to wind down. When you land in a new time zone, this system does not switch over instantly – it needs time to re-set to the new pattern of daylight and darkness.

Two things influence how hard the adjustment is. The first is how many time zones you cross: the greater the shift, the bigger the mismatch to overcome. The second is the direction of travel. Travelling east means losing time and bringing your bedtime earlier than your body wants, which most people find harder. Travelling west means gaining time and staying up later, which the body tolerates more easily – which is why a return trip can feel very different from the outbound leg.

Who is more affected

How badly jet lag hits varies a great deal – two people on the same flight can have quite different experiences. In general, crossing more time zones tends to make it harder, and some older travellers find the adjustment more of a struggle than younger ones. There is no single rule, so it is worth noticing how your own body responds and planning around that.

How long it lasts

Jet lag is temporary. It improves steadily as your body clock catches up with local time, and then resolves without any treatment. As a rule, the further you have travelled – the more time zones between home and destination – the longer the body takes to feel fully back in step, and eastward trips often take a little longer to settle than westward ones. There is no fixed timetable; the sensible expectation is simply that things get better each day rather than staying the same.

How to reduce it – before you travel

Preparation makes a real difference, and the core of managing jet lag is practical rather than medical.

Gradually shift your sleep times towards the destination in the days before you fly – earlier if you are heading east, later if heading west. Even a partial nudge gives your clock a head start;
Arrive well rested. Starting a trip already short on sleep stacks tiredness on top of jet lag, so avoid working through the night before departure;
Plan around it. Where an important meeting or commitment is involved, arriving with time in hand to acclimatise is far kinder than stepping off the plane straight into it.

How to reduce it – during the flight

Once you are on board, a few habits ease the transition:

Stay hydrated and go easy on alcohol and caffeine, both of which disturb sleep and add to dehydration in the dry cabin air;
Move around when you can – a walk down the aisle and simple stretches keep you comfortable on a long flight;
Set your watch and your routine to destination time as you board. Try to sleep or stay awake to match the clock at your destination rather than the one you left behind, so your mind is already on local time before you land.

How to reduce it – at your destination

Arrival is where the biggest gains are made, because this is where light does its work.

Get outdoors into daylight at the right times. Natural light is by far the most powerful tool for resetting the body clock, and being outside is far more effective than indoor lighting;
Keep to local meal and sleep times straight away. Eating and sleeping on the new schedule reinforces the shift and helps your body accept that it has moved;
Use short naps carefully. A brief nap can take the edge off daytime sleepiness, but a long one – or a nap too close to local bedtime – can leave you wide awake at night and set you back;
Be sensible with caffeine. A daytime coffee can help you stay alert while you adjust, but caffeine later in the day makes it harder to sleep when you need to.

Getting the light timing right

Because light is the master signal, when you seek it matters as much as getting it at all, and it depends on your direction of travel. In broad terms, morning light tends to nudge the body clock earlier, which suits eastward travel where you are bringing sleep forward, while evening light tends to push the clock later, which suits westward travel where you are delaying it. You need not follow a rigid formula; the useful idea is that daylight is a lever, and using it in the right part of the day helps steer your clock the way you want.

Melatonin and sleep aids

Some travellers turn to melatonin or short-term sleep aids, but these are not a substitute for daylight and good routine, and not something to reach for on guesswork. Timing, suitability and interactions with other medicines all matter, and official guidance on melatonin for jet lag is not uniform. In Singapore, the sensible course is to discuss it with a doctor or pharmacist first rather than self-prescribing, and to use any such aid cautiously and briefly. Sleeping tablets in particular can leave you groggy and do nothing to correct the underlying clock mismatch. If you take time-sensitive medication, crossing time zones changes when your doses fall due – plan the timing with your doctor before you travel and carry your medicines in your hand luggage.

Coping while you adjust

Patience helps more than anything: jet lag is self-limiting, and each day of daylight and local-time living moves you closer to normal. While you still feel the effects, be mindful of safety. Do not drive, and avoid making important decisions, when you feel very sleepy – drowsiness dulls reaction time and judgement just as tiredness from any other cause does. Go gently at first, keep plans light where you can, and let your routine and the sunshine do the work.

When it might be more than jet lag

Jet lag rarely needs medical attention and settles on its own. It is worth seeing a doctor – a GP or travel clinic, with reliable general guidance also available through HealthHub – if your sleep problems persist well beyond the expected adjustment, if jet lag is a recurring and serious problem, or if you have other health concerns, such as symptoms not typical of jet lag or that leave you feeling genuinely unwell. Ongoing sleep difficulty may reflect something other than travel, and if it does not settle it deserves a proper look. You may also find these guides useful: circadian rhythm disorders and shift work sleep disorder.

Related sleep & health topics

Sources

Cleveland Clinic — Jet lag: definition, time-zone threshold, eastward-worse pattern, light, melatonin, sleep-medication downsides.
NHS — Jet lag: symptoms, self-help before/during/after travel, natural light advice, and its position that melatonin is not recommended on the NHS for jet lag.
CDC Travelers’ Health — Jet lag: pre-travel sleep shifting, strategic light and caffeine, short naps, and consulting a doctor about sleep aids.
Peer-reviewed review (Frontiers in Physiology) — direction-specific light and melatonin timing.

General information only. This guide is general information about sleep and is not a diagnosis or personalised medical advice. See a doctor — a GP, or a sleep, respiratory or ENT specialist — for assessment and treatment of a sleep problem. Do not drive or operate machinery if you are severely sleep-deprived or excessively sleepy, and seek prompt medical advice if you have loud snoring with pauses in breathing, gasping or choking in sleep, or heavy daytime sleepiness — these can be signs of obstructive sleep apnoea.

Jet Lag in Singapore: How to Beat It When You Travel