Jet lag: why it happens, and what actually helps
Your body clock doesn't know you changed time zones. Here's the actual mechanism, and what the evidence says helps.
What jet lag actually is
Jet lag happens when your internal circadian clock — trained to a specific light-dark schedule — is suddenly out of sync with the local time at your destination. It's a genuine physiological mismatch, not just tiredness from travel itself.
Why it gets worse the more time zones you cross
The general rule from circadian research is roughly one day of adjustment per time zone crossed, which is why a 2-hour shift is barely noticeable while an 8-hour shift can take the better part of a week to fully resolve.
Why eastward travel is generally harder than westward
Traveling east requires advancing your body clock (going to sleep earlier than usual), which most people's circadian systems adapt to more slowly than delaying it (staying up later), the adjustment required traveling west — a well-documented asymmetry in circadian research.
Where melatonin's timing-signal role is most directly useful
Because melatonin functions as a timing cue rather than a sedative, it's specifically well-suited to jet lag — timed to your new destination's evening, it can help nudge your body clock toward the new schedule faster than light exposure alone. See melatonin vs valerian for how this differs from herbal sleep support.
Light exposure: the other major lever
Strategic light exposure — bright light at the right time relative to your new schedule, avoiding it at the wrong time — is one of the best-evidenced non-supplement tools for shifting circadian rhythm, and it works alongside, not instead of, melatonin timing.
What doesn't meaningfully help
Alcohol during the flight is commonly used to induce sleep but disrupts sleep architecture and dehydrates, generally making adjustment slower, not faster — one of the more common jet-lag mistakes.
A practical framework
Shifting your schedule (sleep, meals, light exposure) toward your destination's time a day or two before departure, staying hydrated, and using melatonin timed to the new evening are the three most consistently evidenced approaches, used together rather than any single one alone.
Frequently asked questions
How many days does jet lag typically last?+
A rough guideline is about one day of adjustment per time zone crossed, though this varies by individual and direction of travel.
Is jet lag worse flying east or west?+
Generally east, since it requires advancing your body clock, which most people's circadian systems adjust to more slowly than delaying it.
When should I take melatonin for jet lag?+
Generally timed to your destination's evening/intended bedtime, not your origin time zone — this is what makes it useful for timing adjustment specifically.
Does exercise help with jet lag?+
Light exercise, especially outdoors at your destination, can help through both light exposure and general alertness regulation, though it's a supporting factor rather than a primary fix.
Can caffeine help me push through jet lag?+
It can mask sleepiness temporarily but doesn't address the underlying circadian mismatch, and using it late in your destination's day can make the actual adjustment slower.
This article is for general information and isn’t medical advice. Talk to a healthcare professional before starting any new supplement, especially if pregnant, nursing, under 18, or managing a medical condition.
