Jet Lag and Time-Released Medication Dosing Across Time Zones: What Actually Works

When you land in Tokyo after a 14-hour flight from Sydney, your body still thinks it’s 3 a.m. But the sun’s up, your meeting starts in two hours, and your brain is screaming for sleep. This isn’t just tiredness-it’s jet lag, a real, measurable disruption of your internal clock. And if you’ve reached for that time-released melatonin pill thinking it’s the smarter, longer-lasting option, you might be making things worse.

Why Jet Lag Isn’t Just Being Tired

Jet lag isn’t about how long you flew. It’s about your body’s clock being out of sync with the new time zone. Your circadian rhythm-controlled by a tiny group of cells in your brain-runs on a 24-hour cycle. It tells you when to feel alert, when to sleep, when to digest food, even when to release hormones. When you jump across five or more time zones, that clock doesn’t flip instantly. It takes days to adjust.

Studies show you lose about one day of adjustment per time zone crossed. Eastward travel-like flying from Sydney to London-is harder. Your body has to speed up, forcing you to sleep earlier than it’s ready for. Westward travel-say, from New York to Los Angeles-lets you stretch your day, which your body handles more easily. That’s why you might feel fine after flying west but wrecked after flying east, even if the flight time is the same.

The Melatonin Myth: Time-Released Isn’t Better

Most people think longer-lasting means better. If one pill helps, maybe a slow-release version gives you all-night coverage. But that’s exactly what makes it harmful.

Melatonin isn’t a sleeping pill. It’s a signal. Your body naturally releases it at night to say, “It’s time to sleep.” When you take it as a supplement, you’re trying to shift that signal to match your new time zone. But the circadian system doesn’t respond to a steady drip of melatonin. It responds to a sharp, short pulse.

According to the CDC’s 2024 Yellow Book, time-released melatonin “stays in the system too long and confuses the circadian clock.” That’s not a metaphor. It’s science. Immediate-release melatonin clears from your bloodstream in about an hour. Time-released versions? They can stay active for 6 to 8 hours. That means if you take it at 10 p.m. local time to help you sleep, you’re still getting melatonin at 4 a.m.-when your body should be waking up. That’s like turning on a light in the middle of the night and wondering why you can’t wake up.

A 2019 study in Sleep Medicine found that 3 mg of immediate-release melatonin taken at 10 p.m. produced a 1.8-hour phase advance. The same dose of time-released melatonin? Only 0.6 hours. That’s less than a third of the effect. And for eastward travelers-who need the biggest phase advances-this difference can mean the difference between adapting in three days or five.

What the Experts Say

Dr. Charles Czeisler, a leading sleep researcher at Brigham and Women’s Hospital, says bluntly: “Time-released melatonin formulations should be avoided for circadian rhythm adjustment.” The American Academy of Sleep Medicine agrees. Their 2018 guidelines give a strong recommendation (Level A) for low-dose immediate-release melatonin for eastward travel-but say there’s “insufficient evidence” for time-released versions.

Even the European Medicines Agency, which approved a time-released melatonin product called Circadin for insomnia in older adults, specifically excluded jet lag as an approved use. Why? Because the data doesn’t support it.

Travelers themselves are catching on. A 2023 survey of over 5,000 frequent flyers using the Sleep Cycle app found that those using time-released melatonin took 2.4 days longer to adjust than those using immediate-release. On Amazon, time-released melatonin products average 2.8 stars. Immediate-release? 4.1. Common complaints? “Woke up at 3 a.m. feeling wired.” “Felt groggy all morning after taking it for my Tokyo trip.”

How to Use Melatonin Right

If you’re going east-say, from Sydney to New York (15 hours ahead)-here’s what actually works:

1. Take 0.5 to 3 mg of immediate-release melatonin 30 minutes before your target bedtime in the new time zone.
2. Start taking it on the day you depart, or the day you arrive.
3. Continue for 3 to 5 nights.

For a 10-hour time zone jump, most people do well with 1 mg. For 12+ hours, 3 mg is more effective. Don’t go higher-more isn’t better. A 2002 meta-analysis showed 0.5 mg is just as effective as 5 mg for shifting your clock. The higher dose just makes you sleepier.

For westward travel, the advice is less clear. Some experts suggest taking melatonin in the morning upon waking to delay your clock, but this is harder to time and less studied. Light exposure matters more here: get sunlight right after waking to help reset your rhythm.

Timing Is Everything-And It’s Hard

The biggest mistake? Getting the time wrong. If you’re flying east and take melatonin at 7 p.m. local time, you’re signaling your body to sleep when it should still be awake. That can delay your adjustment, not speed it up.

Most people mis-time their doses by two or more hours on their first try. That’s why apps like Timeshifter exist. They use your flight details, chronotype (are you a morning person or night owl?), and sleep history to calculate the exact time to take melatonin. Over 1.2 million travelers have used them as of early 2024.

Without an app, use this rule: Take melatonin at the time you want to fall asleep in the new time zone. If you’re landing in London at 8 a.m. your time, and you want to sleep at 10 p.m. London time, take the pill at 9:30 p.m. London time.

What Else Helps?

Melatonin isn’t magic. It works best with light and routine.

• Get bright light (natural sunlight or a 10,000-lux light box) in the morning after eastward travel. This tells your body it’s time to wake up.
• Avoid blue light from screens after melatonin dosing. Your eyes are sensitive to it-even dim screens can block melatonin production.
• Stay hydrated. Dehydration worsens jet lag symptoms.
• Don’t force sleep. If you’re not tired, stay awake. Sitting quietly in a dark room is better than tossing and turning.

Why Time-Released Melatonin Still Exists

You’ll still see it everywhere. Why? Because it’s marketed as “gentler,” “all-night support,” or “natural sleep aid.” It’s not designed for jet lag. It’s designed for people with insomnia who struggle to stay asleep. That’s why it’s approved in Europe for adults over 55 with sleep maintenance issues.

But jet lag isn’t insomnia. It’s a timing problem. And timing requires precision, not endurance.

The Bigger Picture

The global jet lag market is growing fast-projected to hit $2.9 billion by 2030. But melatonin supplements are unregulated in the U.S. The FDA treats them like food, not medicine. A 2023 FDA warning found some products contained 83% to 478% more melatonin than labeled. That’s dangerous if you’re trying to hit a precise dose.

Forty-two Fortune 100 companies now give employees immediate-release melatonin and timing guidance for international travel. Not one recommends time-released.

Future research is moving toward personalized dosing based on genetics. Scientists at UCSF have found that people with certain gene variants (like CRY1) need melatonin at completely different times. In 2024, they showed some people respond best to melatonin at 8 p.m., others only at 11 p.m.

For now, the best tool you have is simple: Use immediate-release melatonin, take it at the right time, and combine it with light. Skip the time-released version. It’s not helping. It’s holding you back.

What About Other Medications?

Some travelers turn to sleeping pills like zolpidem or stimulants like modafinil. These can help you sleep or stay awake, but they don’t fix your clock. You might feel better the next day, but your body will still be on Sydney time. That means you’ll crash again the next night. Melatonin is the only supplement shown to actually reset your rhythm.

And no, caffeine won’t fix it. It just masks the symptoms. You’ll still be running on empty.