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How Long Does Melatonin Last? A Sleep Doctor Explains

Melatonin can last in your body for four to eight hours. But this will depend on factors like the type of melatonin you take, the dose, and your age.
Published
2021-07-19
Updated
2023-08-11
14 MINS
Written by
Jeff Kahn, M.S., Rise Science Co-Founder
Reviewed by
Chester Wu, MD, Rise Science Medical Reviewer
Our Editorial Standards
We bring sleep research out of the lab and into your life. Every post begins with peer-reviewed studies — not third-party sources — to make sure we only share advice that can be defended to a room full of sleep scientists.
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Updated Regularly
We regularly update our articles to explain the latest research and shifts in scientific consensus in a simple and actionable way.
Woman wondering how long melatonin will last

How Long Does Melatonin Last? 

  • Melatonin can last four to eight hours. But this will depend on factors like the type of supplement you take, the dose, your age, and if you’ve had caffeine.  
  • Melatonin can kick in in as little as 20 minutes, or it can take two hours or longer for you to feel the effects. 
  • The RISE app can tell you when exactly to take melatonin supplements to make them most effective. Or, to skip the supplements altogether, follow RISE’s personalized sleep hygiene reminders to maximize your natural melatonin production and get a good night’s sleep.

Melatonin supplements have become a popular sleep aid. They’re a synthetic form of the natural hormone your body makes to help you fall asleep and keep your sleep-wake cycle in check. But how long they last in your system can depend on a long list of factors. 

Below, we’ll dive into how long melatonin lasts and how long it takes to kick in. Plus, we’ll share how the RISE app can help you increase your melatonin levels without popping a single pill. 

What Does a Sleep Doctor Say?

For a sleep doctor’s opinion, we turned to Rise Science sleep advisor and medical reviewer, Dr. Chester Wu. Dr. Wu is double board certified in psychiatry and sleep medicine.

"Supplemental melatonin tends to last between four and eight hours, but this number can vary widely. The type of supplement you take, the dose, and even your age can all make a difference to how long melatonin stays in your system.”

How Long Does Melatonin Stay in Your System?

Melatonin can stay in your system for four to eight hours.

Melatonin can have a half-life (the time it takes your body to metabolize half of a dose of a medication) of about 20 to 45 minutes or higher. That means if you took a 1-milligram dose of melatonin at 6 p.m., you’d have 0.5 mg of it in your system by about 7 p.m., and 0.25 mg by about 8 p.m., or even less. 

How long melatonin effects last can vary depending on: 

  • Dose: The larger the dose of melatonin, the longer it’ll take to wear off. Melatonin supplements add to your natural levels of the hormone, so if your natural levels are already high, you may have elevated levels of the hormone for longer.
  • Age: Your metabolism slows down as you age, meaning melatonin may last longer in your system the older you are. 
  • Caffeine consumption: Some studies suggest caffeine can reduce melatonin levels and others found it can increase them. So more research needs to be done, but caffeine might cancel out the effects of the supplement, or make them last longer. 
  • Light exposure: Light suppresses melatonin production and signals to your brain that it’s time to be awake, so you’ll be lowering your natural levels of melatonin and sending mixed signals to your brain. 
  • Medication: Certain medications can add to the sleepiness effect of melatonin or increase your melatonin levels or any side effects you feel. These medications include oral contraceptives, central nervous system depressants, and OCD meds. 
  • Smoking: One study found when you smoke and take melatonin, the levels of melatonin in your blood are reduced compared to not smoking, meaning the supplement may wear off more quickly. 
  • The type of supplement: Extended-release or slow-release formulations are designed to take longer to kick in and stay in your body longer than immediate-release or fast-release formulations, which kick in and wear off much faster. You can also get combined immediate and extended-release formulations. It’s not clear whether melatonin gummies, patches, sprays, or pills last different amounts of time in your body. 

Heads-up: The dose you take can affect how long it lasts, but it’s hard to know how much melatonin you're taking exactly. 

A 2017 study found that the amount of melatonin in supplements is often dramatically different from what’s listed on the label. The actual levels of melatonin in the 16 brands ranged from 83% less to 478% more than the amount advertised on the label. 

How Long Does it Take Melatonin to Work?

Melatonin can take about 20 minutes to two hours or more to work.

But the exact time will depend on the type of melatonin supplement you take, (immediate-release melatonin pills will work faster than extended-release ones), the dose (larger doses can kick in quicker than smaller doses), and when you take melatonin (taking it in the afternoon or evening can help you sleep earlier whereas morning melatonin can help you sleep later).

What you’re taking melatonin for also makes a difference. Let’s dive into that. 

To Shift Your Circadian Rhythm 

Shifting the timing of your circadian rhythm, or sleep-wake cycle, is the main use of melatonin. That’s why melatonin is referred to as a chronobiotic or chronobiotic hormone. 

In simple terms, you want to take melatonin about four to five hours before the time you want to sleep to fall asleep earlier than usual, bringing your circadian rhythm forward. And take it at your usual wake time to fall asleep later than usual, pushing your circadian rhythm back. 

How long it takes to “work” all depends on the effect you’re looking for. 

Melatonin levels can reach peak levels in your system quickly — usually within an hour — but then take a long time to wear off. 

If you’re trying to sleep earlier, taking a low dose (think 0.3 mg or lower) can make sure you don’t still have high melatonin levels come morning, which can push back your circadian rhythm, having the opposite effect you’re looking for.

You also want to take a low dose, so you won’t feel sleepy during the day. Taking melatonin in the morning (to fall asleep later than usual) or in the (late) afternoon (to fall asleep earlier than usual), when your melatonin levels are naturally lower, increases the supplement’s sleepiness potential. Taking a low dose of melatonin can help prevent this from happening. 

As with everything to do with melatonin, more research needs to be done. 

To Fall Asleep 

When you take a melatonin supplement, it can reach peak levels in your system in about 15 minutes to 3.5 hours. If you take a large dose, this may happen even faster. And this can make you feel sleepy sooner.   

In this case, melatonin can take about 30 to 60 minutes to work. When you’re taking melatonin more like a traditional sleep aid (a hypnotic), rather than as a chronobiotic, you’re aiming to have peak levels align with when you want to fall asleep. 

Melatonin supplements work best when your natural melatonin levels are low, i.e. during the day. This is why melatonin has been shown to be more effective as a sleep aid for shift workers trying to sleep during the day (although the evidence isn’t conclusive).

If you take it before bed, when your natural melatonin levels are higher, you may fall asleep faster, but this may only result in a few minutes more sleep. Or it may not have an effect at all (it may just act as a placebo, which can still be valuable). 

Once again, more research needs to be done. 

What Does Science Say? 

One small study found when participants took a 10-mg oral dose of melatonin it took about 41 minutes to reach maximum levels in their systems. But just because that’s the time it takes to reach max levels, doesn’t mean that’s the only time you’ll feel the effects. 

And it should be noted 10 mgs is a huge dose of melatonin and is not usually advised. Very few studies use this high of a dose, so the long-term safety of 10 mg isn’t known, and the effects will likely last longer than you want them too. 

Even though 3, 5, and 10 mg doses are available to buy, most clinical trials use melatonin doses of 2 mgs or less, so these larger doses aren’t as well studied. 

Research on jet lag shows a 0.5 mg dose of melatonin is just as effective as a 5 mg dose at shifting your circadian rhythm. And doses above 5 mg appear to be no more effective. It was found, however, that 5 mg doses of melatonin helped people fall asleep faster than 0.5 mg doses. But experts usually recommend smaller doses of no more than 3 mg. 

One last thing, research suggests melatonin may not work long-term, so you don’t want to rely on it as a sleep aid to help you fall asleep every night. We cover other reasons why melatonin may not work for you here.

“There’s no magic number for how long melatonin takes to kick in. When you take it makes a difference. Take melatonin four to five hours before bed to sleep earlier, and in the morning to sleep later than usual. It may take 30 to 60 minutes to kick in if you’re taking it before bed to fall asleep, but it may not be as effective at this time.” — Rise Science Medical Reviewer Dr. Chester Wu. 

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What is Melatonin?

​​Melatonin is a natural hormone your brain makes to help you fall asleep and keep your circadian rhythm in check. This is your roughly 24-hour internal clock that dictates your sleep cycle.

Melatonin is made in the pineal gland in your brain in response to signals from the suprachiasmatic nucleus (SCN), a special group of neurons in the hypothalamus part of your brain. In simple terms, when it’s dark, your brain is prompted to make melatonin.

This usually happens a few hours before your biological bedtime, and this moment is called the dim light melatonin onset (DLMO).

Melatonin lowers your body temperature, blood pressure, stress hormones, and alertness to prime you for sleep. 

Your melatonin levels rise in the evening and are high overnight, and they fall in the early morning and are lower during the day. 

Normal melatonin production
Source: https://sites.psu.edu/lifeitmoveson/2018/01/26/sleep-external-influences/

The hormone is available as an over-the-counter (OTC) supplement in many different forms, including tablets, capsules, liquids, gummies, patches, or sprays. 

It can help you shift the timing of your circadian rhythm earlier or later. And it may help you feel sleepy when you usually wouldn’t, like when your natural melatonin levels are low during the day. 

It’s not as effective when your melatonin levels are already high, such as before bed, so melatonin supplements can be useful when: 

You may also be recommended melatonin by your healthcare provider or a sleep specialist if you’ve got a sleep disorder, like a circadian rhythm disorder, or if you’re an older adult with sleep problems. 

We’ve covered more on what melatonin does here. 

When to Take Melatonin?

Take melatonin about four to five hours before the time you want to fall asleep to help you feel tired earlier than usual.  

If you want to push back your circadian rhythm (ideal for shift workers or those traveling across time zones), take melatonin around your usual wake-up time to sleep later than usual. 

If you want to fall asleep faster, take melatonin 30 to 60 minutes before bed. But heads-up, taking melatonin as a sleep aid may not be that effective, especially if you’re taking it at night or in the late evening when your natural melatonin levels are already high. 

We’ve covered more on how long before bed to take melatonin here.

If you do decide to take melatonin supplements to shift your circadian rhythm, RISE can tell you the best time to take them to help you fall asleep earlier. 

Curious which brand of melatonin to take? We recommend Thorne and USP tested as reputable brands.

RISE app screenshot reminding you when to take melatonin supplements
The RISE app can tell you the right time to take melatonin supplements.

RISE users on iOS 1.202 and above can set up their take melatonin supplements reminder here.

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What Are the Side Effects of Melatonin?

The common side effects of melatonin supplements include:

  • Headaches
  • Nausea 
  • Dizziness
  • Tiredness the next morning
  • Daytime sleepiness  
  • Impaired morning cognition (a 2023 study found young adults had lower morning cognition after taking melatonin the night before)

Less common but possible side effects include:

  • Anxiety
  • Depression
  • Abdominal pain
  • Joint pain 
  • Tremors
  • Seizures
  • Allergic reactions
  • Vivid dreaming

The good news is melatonin isn’t considered addictive

Heads-up: Get medical advice before giving your kid melatonin. There’s not much research into the safety of melatonin supplementation in children. A 2023 study found calls for pediatric melatonin ingestions to US Poison Control Centers increased 530% from 2012 to 2021. They were associated with more than 4,000 hospitalizations and two deaths.  

Can You Overdose on Melatonin?

There doesn’t seem to be a risk of overdosing on melatonin. But more research needs to be done to confirm. 

Melatonin is not regulated by the Food and Drug Administration (FDA) as it’s considered a dietary supplement, so there are no official dosing guidelines or rules.  

Even if there’s no risk of melatonin overdose, taking high doses can increase your chance of experiencing side effects. When you start taking the supplement, take the lowest dose possible and only increase to a higher dose if needed. 

We’ve covered how much melatonin is too much here. 

Overall, melatonin supplements are considered safe to use in the short term. It’s generally recommended you don’t take melatonin every night as more research is needed on the side effects of long-term use. 

Heads-up: People who are pregnant or breastfeeding, transplant recipients, those on medication, and people with certain conditions — diabetes, high blood pressure, seizure disorders, bleeding disorders, or depression — should consult a physician or health care professional before using melatonin supplements.  

Does Melatonin Make it Hard to Wake Up?

Melatonin can make it hard to wake up if you’ve taken a high dose, taken a slow-release melatonin supplement too close to bedtime, only slept for a short amount of time, or taken it during the night. There’s no real evidence taking melatonin during the night works beyond falling asleep slightly faster. 

Melatonin usually wears off in four to eight hours, so if you take it early enough and get enough sleep, you shouldn’t feel any drowsiness from it the next day. 

If you wake up tired, try taking a lower dose or taking a fast-release melatonin supplement instead, as this should wear off before you wake up. Research shows even a 0.5 mg dose of melatonin is enough to help you shift your circadian rhythm earlier.

We’ve covered how many mg of melatonin to take here. 

How Can I Increase My Melatonin Levels Naturally?

You can increase your melatonin levels naturally by getting out in sunlight first thing in the morning and during the day, avoiding light in the run-up to bedtime, and making your bedroom as dark as possible.

With these habits, your body can make all the melatonin it needs to fall asleep. This can be much more effective than melatonin supplements and you won’t have to worry about getting the timing of your supplements right. 

Here’s more on those key tips: 

  • Get out in sunlight first thing in the morning: This will reset your circadian rhythm for the day and increase your body’s production of serotonin. Roughly 12 hours later, that serotonin gets converted into melatonin to prepare your body for sleep. Aim to get out for 10 minutes of natural light, or 15 to 20 minutes if it’s overcast or you’re sitting by a window. 
  • Get out in sunlight during the day: This can make you less sensitive to light messing with your melatonin levels in the evening. Work by a window, go for a lunchtime walk, and exercise outside. 
  • Avoid light in the run-up to bedtime: Research shows exposure to room light in the hours before bed can delay and shorten melatonin production. About 90 minutes before bed, turn down the lights and put on blue-light blocking glasses to keep melatonin high. 
  • Make your bedroom as dark as possible: Use blackout curtains and an eye mask, and turn off or cover any electronics that emit light. Keep the lights off or as low as possible if you wake up in the night to use the bathroom. 
  • Avoid alcohol three to four hours before bedtime: Research shows even a moderate dose of alcohol one hour before bed can reduce melatonin production. We recommend avoiding alcohol three to four hours before bed to stop it from messing with your sleep. 

These four behaviors fall under something called sleep hygiene. With good sleep hygiene, your body can produce all the melatonin it needs for a good night’s sleep. 

RISE can tell you when to do 20+ sleep hygiene habits at the time that’ll make them the most effective for you. 

RISE app screenshot showing you sleep hygiene habits
The RISE app can tell you the best time to do 20+ sleep hygiene habits.

Expert tip: There’s a time of night when your body’s natural rate of melatonin production will be at its highest. In the RISE app, we call this your Melatonin Window. Head to bed during this roughly one-hour window of time to make the most of your brain’s natural melatonin. You can think of RISE as a safer alternative to melatonin supplements

All this will help you meet your sleep need, the genetically determined amount of sleep you need each night. RISE works out this number for you based on a year’s worth of phone use data and sleep science algorithms. 

And it may be higher than you think. We looked at the sleep needs of 1.95 million RISE users aged 24 and over and found the median was eight hours. But 48% of users need eight hours or more sleep a night. 

We looked at the sleep needs of 1.95 million RISE users aged 24 and over and found the median was eight hours. But 48% of users need eight hours or more sleep a night. 
The RISE app can work out how much sleep you need.

RISE users on iOS 1.202 and above can set up their 20+ in-app habit notifications here

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The Best Source of Melatonin? Your Body 

Melatonin supplements can last from four to eight hours. And this number can change depending on the type of melatonin you take, the dose, and your age. 

To stop worrying about how long supplemental melatonin lasts, turn to the safest, cheapest, and best melatonin out there: the kind your brain makes. 

Practice good sleep hygiene to make sure your body can produce all the melatonin you need to fall asleep. And if you do decide to take melatonin, the RISE app can tell you the best time to take it so you feel sleepy at the right time. 

Melatonin works fast, but good sleep hygiene is fast, too. We found 80% of RISE users get better sleep within five days.

FAQs

How long does melatonin last?

Melatonin can last four to eight hours. It has a half-life of 20 to 45 minutes. How long melatonin lasts depends on the type of supplement you take, your age, and whether you smoke, consume caffeine, or take medication. Fast-release melatonin supplements can last less time than extended-release melatonin.

How long does 2 mg of melatonin last?

Two mg of melatonin may last for four to eight hours. How long 2 mg of melatonin lasts exactly will depend on the type of supplement you take, your age, and whether you smoke, consume caffeine, or take medication. The larger the dose of melatonin you take the longer it’ll likely last in your system.

How long does 3 mg of melatonin last?

Three mg of melatonin may last for four to eight hours. How long 3 mg of melatonin lasts exactly will depend on the type of supplement you take, your age, and whether you smoke, consume caffeine, or take medication. The larger the dose of melatonin you take the longer it’ll likely last in your system. Small doses of 2 mg are usually used in clinical trials, so more research needs to be done on how long larger doses last.

How long does 5 mg of melatonin last?

Five mg of melatonin may last for four to eight hours. How long 5 mg of melatonin lasts exactly will depend on the type of supplement you take, your age, and whether you smoke, consume caffeine, or take medication. The larger the dose of melatonin you take the longer it’ll likely last in your system. Small doses of 2 mg are usually used in clinical trials, so more research needs to be done on how long larger doses last.

How long does it take for 10 mg of melatonin to wear off?

Ten mg of melatonin may wear off in four to eight hours. How long 10 mg of melatonin lasts exactly will depend on the type of supplement you take, your age, and whether you smoke, consume caffeine, or take medication. The larger the dose of melatonin you take the longer it’ll likely last in your system. Small doses of 2 mg are usually used in clinical trials, so more research needs to be done on how long larger doses last.

How long does melatonin take to wear off?

Melatonin can take four to eight hours to wear off. It has a half-life of 20 to 45 minutes. How long melatonin takes to wear off depends on the type of supplement you take, your age, and whether you smoke, consume caffeine, or take medication. Fast-release melatonin supplements can wear off faster than extended-release melatonin.

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