Jet Lag: Why It Happens and How to Reset Faster
What jet lag is, why flying east is harder than west, and which methods — light, melatonin, schedule — genuinely speed up resetting your body clock.
Contents
Jet lag is a mismatch between your body clock and the new local time after a fast flight across several time zones. Your body is still on the old time while everything around you is on a new one: you feel sleepy by day, cannot sleep at night, and add grogginess and digestive upset. The reset runs at roughly one day per zone crossed, but you can speed it up — with light, melatonin and schedule. And yes, flying east is objectively harder.
What happens to the clock
The brain has a "master clock" that synchronises the whole body with the day–night cycle. On a fast flight across several zones, external time changes abruptly while the body clock changes slowly. A gap opens: the body releases melatonin and drops its temperature "at the wrong time", and sleep and wakefulness no longer match the local schedule.
This is exactly why a short one- or two-zone flight is barely felt, while a transatlantic or transcontinental one knocks you out for several days.
Three levers for resetting
| Method | How it works | Evidence |
|---|---|---|
| Light | Shifts the master clock; the strongest regulator | High |
| Melatonin | Helps shift the rhythm and fall asleep | Good, especially eastward |
| Schedule and prep | Shifts the clock toward the new zone in advance | Moderate, helps |
Light is the main tool. The general principle: flying east, catch bright morning light and avoid early-evening light; flying west, the opposite. The exact "window" depends on the number of zones, and for long flights it is handy to check a ready-made schedule.
Melatonin taken at destination bedtime helps both shift the rhythm and fall asleep. It is one of the few methods with good evidence specifically for jet lag. The timing matters more than the dose.
Читайте также: Melatonin: does it work and who actually needs it
What to do in practice
- 2–4 days before the trip, gradually shift your sleep time toward the new zone: earlier before an eastward flight, later before a westward one.
- On the plane, set your watch to the destination time right away and, if possible, sleep on the new schedule rather than the old one.
- On arrival, actively manage light (seek or avoid it at the right hours) and stick to the local routine — eat and sleep on the new time, even if it takes effort.
- Caffeine can help alertness in the local morning, but avoid it in the second half of the day so it does not disrupt night sleep.
Читайте также: Sleep hygiene: what works and what is just internet advice
You cannot fully avoid jet lag on a long flight, but managing light and schedule well cuts it several-fold. The key is not to "wait it out" but to actively adjust your clock to the new time from day one.
Читайте также: Chronotype: night owl or early bird, and can it be changed
FAQ
What is jet lag?+
It is a mismatch between your body clock and the new local time after a fast flight across several time zones. Your body is still on the old time while everything around you is on a new one — hence daytime sleepiness, night-time insomnia, grogginess and digestive upset.
Why is flying east harder?+
The human body clock runs slightly longer than 24 hours, so it is more natural to shift it later (flying west 'lengthens' the day) than earlier. Flying east requires going to bed and waking earlier than your internal time, which is harder. Recovery is roughly one day per time zone.
Does melatonin help with jet lag?+
Yes, it is one of the few methods with good evidence. Melatonin taken at destination bedtime helps shift the rhythm and fall asleep when crossing several zones, especially eastward. Doses are usually small; the timing matters more than the dose.
How do I use light to reset?+
Light is the strongest clock regulator. The general principle: flying east, catch bright morning light and avoid early-evening light; flying west, the opposite. The exact timing depends on the number of zones, so for long flights it is handy to use a ready-made schedule.
Can I prepare in advance?+
Yes. A few days before the trip you can gradually shift your sleep time toward the new zone (earlier before an eastward flight, later before a westward one) and manage light accordingly. Even partial preparation reduces the severity of jet lag.
References
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