Melatonin works for jet lag only when the clock time is right, because taken at the wrong hour it can push your rhythm the wrong way. For eastward trips the evidence backed window is the local evening, roughly four hours before your target bedtime. This guide returns that local dose time, and explains why westward travel usually needs evening light instead.
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Scientific references
Melatonin is the hormone of biological night, secreted when darkness falls and read by the brain as a timestamp. Swallowed at the right moment it tells the internal clock that night has arrived, dragging sleep, temperature and appetite rhythms with it. Swallowed carelessly it confuses the same system, which is why timing, not dose, is the whole art of travel melatonin.
Eastward Protocol
Flying east demands advancing the clock, falling asleep earlier than feels natural. The Cochrane reviewed approach takes zero point five to three milligrams in the early local evening, around four hours before the intended bedtime, for the first few days after arrival. A traveler targeting eleven at night doses near seven in the evening. Morning bright light at the destination doubles the effect, pushing the clock the same direction.
Westward Is a Different Problem
Westward travel needs delay, staying up later, and here evening melatonin fights the goal. Light is the better tool, seeking bright evening exposure and shading early morning. Melatonin is generally unneeded for pure westward trips, which is why this guide returns none for that direction.
Dose Small
Studies find half a milligram shifts clocks about as well as five, with less next day grogginess. The mega doses sold in pharmacies reflect marketing, not physiology. Slow release forms suit sleep maintenance while fast release suits clock shifting.
Melatonin interacts with anticoagulants and is best avoided in pregnancy without medical advice. Quality varies wildly between brands since it sells as a supplement in many countries, so pharmacy grade products are worth seeking.