For jet lag, 0.5 to 1 mg of melatonin is often enough to shift your internal clock. That’s far less than most supplements on store shelves, which typically come in 3, 5, or even 10 mg tablets. Higher doses don’t work better for resetting your rhythm, and they can actually backfire by leaving excess melatonin in your system at the wrong time of day.
Why Low Doses Work Better
Melatonin for jet lag isn’t really a sleep drug. It’s a timing signal. Your brain naturally produces melatonin in the evening to mark the start of your biological night, and a small supplemental dose mimics that signal, telling your internal clock to shift earlier or later depending on when you take it. A dose as small as 0.5 mg appears just as effective as 5 mg or higher at producing this circadian shift, though some evidence suggests higher doses may have a mild sedative effect on top of the clock-shifting benefit.
The CDC and the American Academy of Sleep Medicine both caution against doses above 5 mg. When you take a large dose, melatonin lingers in your bloodstream for hours. As your body metabolizes it, elevated levels can spill over into times of day when melatonin should be absent, which confuses the very clock you’re trying to reset.
When to Take It Matters More Than How Much
Timing is the single biggest factor in whether melatonin helps or hurts. Taking it at the wrong point in your cycle can push your clock in the opposite direction, making jet lag worse. The basic rule: melatonin taken in the evening (when your body thinks it’s afternoon or early evening) nudges your clock earlier, which is what you want after flying east. Melatonin taken in the morning at your destination nudges your clock later, which helps after flying west.
For eastbound travel, take 0.5 to 1 mg about 30 minutes before your desired bedtime in the new time zone. This tells your brain that nighttime is arriving earlier than it expects, gradually pulling your sleep schedule forward.
For westbound travel, the approach is different. Take melatonin in the morning at your new destination. This creates a “phase delay,” signaling to your brain that night lasted longer than usual, which shifts your clock to a later schedule. Most people find westbound jet lag easier to manage since staying up later feels more natural than forcing yourself to sleep earlier, so you may not need melatonin at all for short westward trips.
One important caveat: taking melatonin between midnight and 5 a.m. (your body’s internal clock time, not the local clock) is largely pointless. Your brain is already flooding itself with natural melatonin during those hours, so adding more doesn’t produce an additional shift.
How Many Days to Use It
Your body adjusts to a new time zone at a rate of roughly 1 to 1.5 hours per day when shifting your clock earlier (eastbound travel) and about 2 hours per day when shifting later (westbound). So a six-hour eastbound shift, like New York to Paris, might take four to five days of adjustment. Plan to use melatonin each night or morning (depending on direction) until you feel aligned with local time. For most trips, that means three to five days of use.
If your trip is very short, say two or three days, it may not be worth trying to shift your clock at all. You’ll start adjusting just in time to fly home and face the reverse shift.
Pairing Melatonin With Light Exposure
Melatonin works best as part of a two-tool strategy that includes timed light exposure. Light is the strongest signal your brain uses to set its clock, and melatonin enhances the effect. Research from the University of Pennsylvania found that combining bright light with a 0.5 mg dose of melatonin can increase your daily clock shift by about an additional hour compared to light alone.
The practical version: after flying east, seek bright light (sunlight is ideal) in the morning at your destination and avoid it in the late evening. After flying west, seek light in the late afternoon and evening, and avoid bright morning light for the first couple of days. Sunglasses are a simple way to block light during your avoidance windows. Pairing these light habits with properly timed melatonin gives you the fastest adjustment.
Watch for Supplement Quality Issues
Melatonin is sold as a dietary supplement in the United States, which means it doesn’t go through the same quality checks as prescription drugs. A study highlighted by the American Academy of Sleep Medicine found dramatic inconsistencies in melatonin products: the actual melatonin content varied by as much as 465% between different lots of the same product. Some supplements contained far more melatonin than labeled, and 26% of tested products also contained serotonin, a completely different compound that shouldn’t be there.
To reduce the risk of getting an unreliable product, look for brands that carry a third-party verification seal from organizations like USP or NSF International. These seals indicate the product has been independently tested to confirm it contains what the label claims.
Side Effects and Interactions
At the low doses used for jet lag, side effects are uncommon. When they do occur, the most frequent ones are headache, dizziness, nausea, and daytime drowsiness. Less common effects include vivid dreams or nightmares, brief feelings of irritability, and stomach cramps. Avoid alcohol while taking melatonin, as it amplifies the sedative effect.
Melatonin can interact with several types of medication. It may worsen blood pressure control if you take blood pressure drugs, increase sedation when combined with other sleep aids or central nervous system depressants, interfere with blood sugar management in people on diabetes medications, and reduce the effectiveness of anti-seizure drugs. If you take any of these, check with your pharmacist before adding melatonin.
Melatonin for Children and Jet Lag
There are no specific pediatric guidelines for melatonin and jet lag, but general pediatric sleep guidance suggests starting at the lowest available dose, typically 0.5 to 1 mg, given 30 to 90 minutes before the target bedtime. Most children who respond to melatonin don’t need more than 3 mg. It can help older children and teens reset their schedules after travel or vacation disruptions, though younger children often adjust to new time zones faster than adults simply because their sleep drive is stronger.