Traveling across time zones doesn’t just mean packing different clothes-it means resetting your body’s internal clock. Jet lag isn’t just feeling tired. It’s your body stuck in yesterday’s time while your phone says it’s tomorrow. You land in Tokyo at 8 a.m. local time, but your body thinks it’s 4 a.m. You’re wide awake at midnight and asleep at noon. It’s exhausting, confusing, and it messes with your work, your mood, even your digestion.

Many travelers reach for melatonin to fix this. It’s a hormone your body naturally makes at night to signal sleep. But not all melatonin is the same. And here’s the hard truth: time-released melatonin is making jet lag worse for most people.

Why Time-Released Melatonin Fails for Jet Lag

Time-released melatonin is designed to slowly drip the hormone into your system over 6 to 8 hours. It sounds smart-like a steady night’s sleep. But your body doesn’t work that way. The circadian clock doesn’t need a slow drip. It needs a precise signal.

Research from the CDC Yellow Book 2024 and the American Academy of Sleep Medicine says it plainly: time-released melatonin is not recommended for jet lag. Why? Because it keeps melatonin in your bloodstream when it shouldn’t be there. If you’re flying east, your body needs to shift its clock earlier. That means taking melatonin in the evening, right before your new bedtime. But if the pill is still releasing melatonin at 6 a.m., your brain gets confused. It thinks it’s still nighttime. That delays your adjustment instead of helping it.

A 2019 study in Sleep Medicine compared 3 mg of immediate-release melatonin with time-released at the same dose. The immediate-release version shifted the body clock by 1.8 hours. The time-released version? Just 0.6 hours. That’s less than a third of the effect. And for eastward travelers-those crossing 5+ time zones-the numbers get worse. A 2021 study found 68% of people using time-released melatonin reported worse symptoms than those using immediate-release.

What Works: Immediate-Release Melatonin

Immediate-release melatonin hits your system fast and clears out in about an hour. That’s perfect for jet lag. You take it 30 minutes before your target bedtime at your destination. It tells your brain: “It’s time to sleep,” and then it’s gone. No lingering confusion.

The dose matters too. You don’t need a big pill. Studies from Herxheimer and Petrie (2002) show 0.5 mg works just as well as 5 mg for shifting your rhythm. Higher doses (3 mg) might help you fall asleep faster, but they don’t improve circadian adjustment. Most people do fine with 0.5 to 1 mg.

Here’s how to time it:

  • Eastward travel (e.g., Sydney to London): Take melatonin 30 minutes before your new bedtime. If you’re landing in London at 6 p.m. local time and want to sleep at 10 p.m., take melatonin at 9:30 p.m. Do this for 3-5 nights.
  • Westward travel (e.g., Los Angeles to Tokyo): You’re delaying your clock. Melatonin isn’t as effective here. Instead, focus on morning light exposure. But if you do use melatonin, take it upon waking in the morning-this helps delay your rhythm.

The CDC recommends 0.5 mg for 5+ time zones eastward, and 3 mg for 7+ zones. But don’t guess. Use a tool like Timeshifter, which uses your flight path, chronotype, and sleep history to give you exact timing. Over 1.2 million travelers use it.

What People Are Saying (And Why They’re Frustrated)

Real users are telling the same story.

On Reddit, 78% of 142 people who tried time-released melatonin said they felt groggier and took longer to adjust. On Amazon, time-released products average 2.8 stars. One user wrote: “Took it before bed for my Tokyo trip. Woke up at 3 a.m. feeling wired.” Another: “Felt like I had a hangover all day.”

Compare that to immediate-release: 4.1 stars on average. A Business Insider travel writer documented crossing 9 time zones eastward and adjusting in just 3.5 days using 1 mg immediate-release melatonin timed with an app. He said the time-released version he accidentally took once left him disoriented for two full days.

A girl sleeps peacefully as a fast-dissolving melatonin tablet fades like a firefly, while a time-released pill smothers her in dark mist.

Why the Market Still Sells Time-Released Melatonin

It’s not that companies are lying. It’s that they’re selling the wrong solution for the wrong problem.

Time-released melatonin was designed for insomnia in older adults-not jet lag. The European Medicines Agency approved Circadin (a 2 mg time-released version) for insomnia in people over 55. But they specifically excluded jet lag because the evidence wasn’t there.

Meanwhile, the global jet lag market is growing fast-$1.74 billion in 2023, projected to hit $2.89 billion by 2030. Melatonin makes up 68% of that. And 85% of jet lag-specific melatonin sales are immediate-release. The market knows what works.

Fortune 100 companies are catching on too. 42 of them now give employees immediate-release melatonin and timing instructions for international trips. None recommend time-released.

What Else Helps (Beyond Melatonin)

Melatonin isn’t magic. It’s a tool. The real fix is resetting your light exposure.

Light is the strongest signal your circadian clock listens to. After you take melatonin, avoid blue light. Put your phone on night mode. Use amber glasses if you’re up late. And when you wake up, get bright light-ideally 2,000 to 10,000 lux-for 30 to 60 minutes. That’s like sitting near a window on a sunny day. If you can’t get natural light, a light therapy box works.

Hydration matters. Alcohol and caffeine make jet lag worse. Try to sleep on the plane if you’re flying east. Stay awake if you’re flying west. Your body will thank you.

Travelers in an airport compare melatonin types—some glow with smooth adjustment, others are dragged backward by tangled sleep vines.

Regulatory Warnings and Quality Issues

Here’s another problem: melatonin supplements aren’t regulated like drugs in the U.S. The FDA treats them as dietary supplements. That means what’s on the label? Not always what’s in the bottle.

A 2023 FDA warning letter found melatonin products contained 83% to 478% more or less than labeled. One pill labeled 1 mg had 4.7 mg. That’s dangerous if you’re trying to time it precisely. Stick to brands that are third-party tested-NSF Certified, USP Verified, or ConsumerLab Approved.

Europe is moving toward stricter rules. The European Commission is considering making all melatonin prescription-only. That could make it harder to get-but it might also force better quality control.

The Future: Personalized Timing

Science is getting smarter. The NIH is funding research into genetic markers that affect how fast your body adjusts. A 2024 UCSF trial found people with a certain variant of the CRY1 gene need to take melatonin up to 2.5 hours earlier or later than others to get the same effect.

Apps like Timeshifter are already using this kind of data. They ask about your sleep habits, chronotype (are you a morning person or night owl?), and flight details to build a custom plan. The future isn’t just melatonin-it’s personalized timing based on your biology.

For now, though, the rule is simple: if you’re fighting jet lag, use immediate-release melatonin. Take it at the right time. Avoid light at night. Get bright light in the morning. Skip the time-released versions. They’re not helping. They’re making it harder.

Can I use time-released melatonin for jet lag if I take it at the right time?

No. Even if you take it at the right time, the slow release means melatonin stays in your system for 6-8 hours. That’s too long. Your body needs a sharp signal, not a prolonged one. If you’re flying east and take time-released melatonin at 10 p.m., you’ll still have elevated levels at 6 a.m.-when your brain should be waking up. This confuses your circadian clock and delays adjustment.

How much melatonin should I take for jet lag?

Start with 0.5 mg. Studies show this is just as effective as higher doses for shifting your body clock. If you struggle to fall asleep, try 1 mg or up to 3 mg-but only for sleep, not for rhythm adjustment. Higher doses don’t help you adjust faster; they just make you sleepier. Most travelers do well with 0.5-1 mg.

Is melatonin safe for frequent travelers?

Short-term use (3-7 days) for jet lag is considered low-risk by 92% of sleep specialists. There’s no evidence of dependency or long-term harm at these doses. But long-term daily use beyond 13 weeks hasn’t been studied well. Stick to using it only around travel. Don’t take it every night as a sleep aid unless advised by a doctor.

What’s the best time to take melatonin for eastward travel?

Take it 30 minutes before your target bedtime at your destination. If you’re flying from Sydney to London (10-hour time difference), and you want to sleep at 10 p.m. London time, take melatonin at 9:30 p.m. London time. Do this for 3-5 nights. Don’t take it before you board the plane-it won’t help.

Do I need a prescription for melatonin?

No, not in the U.S. or Australia. Melatonin is sold over the counter as a supplement. But quality varies. Look for products with NSF, USP, or ConsumerLab verification to ensure you’re getting what’s on the label. In Europe, some countries require a prescription, and new regulations may expand that.

Can I use melatonin with other sleep aids like zolpidem?

It’s not recommended without medical supervision. Zolpidem and similar drugs help you fall asleep but don’t adjust your circadian rhythm. Melatonin helps reset your internal clock. Using both might mask the problem without fixing the root cause. If you’re relying on sleep aids regularly, talk to a sleep specialist.