How Long Does Melatonin Last? It Varies Widely

Melatonin can stay in your system for four to eight hours, but by practicing good sleep hygiene, you may not need to take any at all.
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Jeff Kahn, M.S., Rise Science Co-Founder
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How long does melatonin take to work, and how long does melatonin last? If you’re having trouble sleeping and you’re asking these questions about melatonin supplements, there are two other questions to ask yourself first: 

  • Why am I not sleeping through the night? 
  • Do I really need to take a melatonin supplement? 

Although melatonin is among the most popular supplements in the United States, you don't need to take it to fall asleep quickly and sleep through the night. That’s because there is another form of melatonin that’s completely free and far superior to anything you can buy. And it’s made inside your own brain! 

The melatonin your body produces plays an essential role in your ability to fall asleep and stay asleep at night. And finding ways to optimize this biological process will help you get the sleep you need, so you have ample energy during the day. Designing a daily schedule that follows your circadian rhythm, or internal clock, is the best way to support your body’s melatonin production for the best sleep you can get. 

Rest assured, this article will answer your questions about melatonin supplements. But our main goal is to share tips on how you can get the sleep you need without spending a dime. We’ll explain how good sleep hygiene — especially being strategic about the timing of your light exposure — can help you make the most of your body’s natural melatonin production for optimal sleep and daytime energy. 


What Is Melatonin?

​​Melatonin is a naturally occurring hormone that promotes sleepiness. The melatonin your brain produces helps regulate your circadian rhythm — the internal clock that tells your body when to sleep and when to be awake over a roughly 24-hour cycle. 

Even though melatonin is naturally produced by your body, over-the-counter melatonin supplements (exogenous melatonin) are also available. They are packaged and marketed as sleep aids and can be made synthetically or from animal glands. You can get these as tablets, capsules, liquids, gummies, or sprays. 

Before seeking out melatonin that was made in a lab or bottled in a factory, why not look for ways to boost the unbranded, bespoke version produced by your very own brain? It’s easier than you might think. And asking the right questions can help shed some light on how your natural melatonin works. Let’s start with the basics.

How and When Does Your Brain Produce Melatonin?

Melatonin is produced at night in the brain’s pineal gland in response to signals from the suprachiasmatic nucleus (SCN), a special group of neurons in the hypothalamus. As the master clock of your circadian rhythm, the SCN is attuned — via the retina and optic nerve — to the cycle of changing light we experience every 24 hours. In the dark of night, the SCN prompts the pineal gland to secrete melatonin. The TL;DR here is — to produce melatonin, you have to be in the dark.

How Does Melatonin Make You Feel Sleepy at Night?

RISE app screenshot showing your melatonin window which can tell you the ideal time to go to sleep.
The RISE app can tell you your ideal bedtime each night.

After dark, melatonin preps your body for sleep by lowering your body temperature, blood pressure, stress hormones, and alertness. Your brain starts producing melatonin about two hours before your biological bedtime, and this time is known as the dim light melatonin onset (DLMO). 

A couple of hours after this, your brain will be making the most melatonin it will all night. In the RISE app, we call this your Melatonin Window. Going to bed during this window will give you the best chance of falling asleep quickly and staying asleep through the night. The tricky thing is the timing of your Melatonin Window can change each day depending on how much sleep you got the night before. The RISE app can predict your circadian rhythm and tell you when your Melatonin Window is each night, so you can aim to go to sleep in this roughly one-hour window, meaning you can skip the supplements altogether. For a more in-depth look at what does melatonin do, head here.

How Does Light Affect Melatonin Production and Sleep? 

Just as darkness prompts the production of melatonin, exposure to light suppresses it. That works out perfectly in the morning, as exposure to sunlight can help you feel more awake as you start your day. But light exposure at night can be problematic, especially in the 90 minutes before bedtime. Using artificial lighting at night can trick your brain into thinking it’s still daytime. Even small amounts of light exposure will inhibit or delay natural melatonin release and make it much more difficult to fall asleep and stay asleep during the night. 

How Can I Increase Melatonin Levels Naturally?

RISE app screenshot showing you when to get and avoid bright light.
The RISE app can tell you when to get and avoid bright light exposure.

Supplements are useful when you want to sleep when your body wouldn’t naturally be sleeping — like when you’re trying to adjust to jetlag, night shifts, or move your sleep schedule. But most of the time, you don’t need it to fall asleep each night. 

Your brain can make all the melatonin you need for a good night’s sleep, you just need to make sure it can do so by maintaining good sleep hygiene. 

Good sleep hygiene — the upkeep of behaviors that influence the way you sleep — starts first thing in the morning and is essential for optimal melatonin production. As light can so easily influence how much melatonin your brain makes, getting it at the right times is key for better sleep and more energy the next day. 

Follow these light guidelines to optimize your sleep and energy levels:

  • Let the sunshine in: Open the curtains or go outside for a walk. When you expose yourself to sunlight soon after you get up in the morning, your brain stops producing melatonin, signaling the end of the sleep phase and the beginning of your waking hours. It will also set you up for restful sleep later that night. Exposing your skin and eyes to sunlight upon waking helps increase your body’s production of serotonin. Roughly 12 hours later, that serotonin gets converted into melatonin to help prep your body for sleep as your bedtime approaches.
  • Get natural light throughout the day: Getting four to five hours of natural light during the day can make you less sensitive to bright light in the evening. If you can’t be out in the sun that long, try working by a window. 
  • Don’t light up your night: Since darkness is your body’s cue to increase melatonin production, make sure your nighttime environment reflects what’s happening outdoors. Turn off bright overhead lights in favor of dim lamps where necessary. And try to steer clear of blue light, as it can be especially disruptive to melatonin production. Because avoiding blue light — which comes from the screens of our various electronic devices — is not always possible, get a pair of blue-light blocking glasses to wear at night, especially in the 90 minutes before your bedtime.  
  • Create a zero-light sleep zone: A pitch-black sleep environment is the best way to help your body maintain its natural melatonin levels during the night. Use an eye mask and blackout curtains or blinds. And because we have photoreceptors all over our skin, eliminating all light in your bedroom is crucial. Even the seemingly insignificant light coming from a nightlight or the glowing green numbers on your digital alarm clock can impede your ability to sleep. 
  • Don’t turn on the lights if you wake up in the middle of the night: For example, if you need to get up to use the bathroom during the night, use your phone flashlight instead of turning on bright overhead lights.

RISE can tell you the exact times you should get light exposure and when to avoid it each day. It can also remind you when to put on blue-light blocking glasses in the evening based on the timing of your Melatonin Window.

If you manage to get your light exposure perfectly timed, but you’re still having persistent sleep problems, you may want to seek medical advice to address any possible sleep disorders or other underlying health problems. And if your doctor recommends melatonin as a sleep aid, be sure to do your homework to determine your best course of action.


Can Melatonin Supplements Be Useful?

RISE app screenshot showing you when to take melatonin supplements.
The RISE app can tell you the best time to take melatonin supplements.

While a melatonin dietary supplement is no substitute for maintaining good sleep hygiene habits to support the body’s natural melatonin production, in certain situations, getting a little exogenous melatonin from a bottle can be useful. 

Melatonin can be useful when: 

  • Overcoming jetlag
  • Adjusting to shift work 
  • Shifting your sleep schedule 

Research shows melatonin supplements ranging from 0.5 mg to 5 mg can help you overcome jetlag quicker. And it works for both westbound and eastbound flights, so when you want to move your body clock forwards or backwards. There is anecdotal evidence that suggests melatonin supplements may help shift workers sleep during the day when working night shifts. But a report published by the National Institutes of Health (NIH) found that the evidence was based on small studies whose results were inconclusive. Light therapy has proven to be a more reliable way to improve sleep outcomes for shift workers facing high circadian disruption. Melatonin supplements may be more helpful in correcting moderate circadian misalignment. For example, if you’re a night owl looking to shift your sleep-wake cycle to that of a morning person, a supplement can help reset your sleep schedule. Evidence suggests that taking 5 mg of melatonin five hours before your DLMO can move evening melatonin production up by 1.5 hours and make it easier to fall asleep earlier.

We covered more about how much melatonin you should take in different situations here. And for those times when melatonin supplements are useful, RISE can tell you the best time to take them to feel sleepy at your desired bedtime. 

How Long Does Melatonin Take to Work?

Different forms of exogenous melatonin are absorbed at different rates. As a rough estimate, melatonin in pill form can begin to take effect within 30 minutes. But it may take as little as 20 minutes or as long as two hours to kick in.

How Long Does Melatonin Last?

Depending on body weight, dosage, and supplement form, exogenous melatonin stays in your system anywhere from four to eight hours. Melatonin has a half-life — the time it takes the body to metabolize half of a dose of a medication or supplement — of approximately 20-50 minutes

That means if you took 1 mg 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. On average, it takes four to five half-lives for the body to eliminate a melatonin supplement.

How long melatonin lasts will be different for everyone. It all depends on: 

  • Age
  • Body weight
  • How often you use melatonin 
  • If you’ve had caffeine
  • If you smoke 
  • If you get bright light exposure after taking it 
  • Other medications 
  • The dose of the supplement 
  • The type of supplement — slow-release formulations are specifically designed to stay in your system longer whereas immediate-release supplements dissolve much faster.

Are There Side Effects, and Can You Overdose on Melatonin Supplements?

Because melatonin is not regulated by the Food and Drug Administration (FDA), there are no official dosing guidelines. Though you won’t find recorded cases of lethal melatonin overdoses amongst adults, taking high doses of exogenous melatonin increases your chance for experiencing common side effects

Possible side effects of melatonin supplements include:

  • Headaches,
  • Nausea, 
  • Dizziness, Daytime sleepiness

Although less common, some people may experience unpleasant side effects such as:

  • Anxiety
  • Depression
  • Abdominal pain
  • Joint pain 
  • Tremors
  • Seizures
  • Allergic reactions. 

The good news is melatonin isn’t considered addictive

Are Melatonin Supplements Safe?

While short-term use seems to be safe, there’s limited research into the side effects of long-term use, so it’s generally recommended you don’t take melatonin every night

Although melatonin supplements are often considered less habit forming than other common sleep aids, they’re not for everyone. Women who are pregnant or breastfeeding, transplant recipients, 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.  

The American Academy of Sleep Medicine recently launched an investigation into the safety of melatonin. For now, it’s recommending children and those with insomnia avoid the supplement. 

Likewise, individuals on certain medications should avoid melatonin supplements, as they may reduce the medication’s efficacy or cause potentially harmful interactions. Prescription and over-the-counter medications that should not be taken in combination with melatonin include blood pressure and diabetes medications, certain contraceptives, immunosuppressants, anticoagulants (blood thinners), anticonvulsants (anti-seizure medications), and some depression medications. 

Although we can buy exogenous melatonin in unregulated over-the-counter supplements in the United States, the fact that other countries — including the United Kingdom — require a prescription for melatonin is a reason to give it some serious consideration before popping open a bottle of melatonin pills. Not enough is known about the long-term effects of taking melatonin, especially at high doses. 

Melatonin affects us all differently, so starting with the lowest dose is the best way to reduce your chances of developing unwanted side effects, but even that can be challenging and confusing. 

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 tested ranged from 83% less to 478% more than the amount advertised on the label. So you may be taking a much lower dose or a significantly higher dose of melatonin than you were led to believe.

We covered more about how much melatonin is too much here. 

The Best Source for Melatonin? Your Own Body

Melatonin supplements can last in your system for up to eight hours, but you don’t actually need them to fall asleep each night. Melatonin plays an important role in keeping your sleep schedule in line with your circadian rhythm. Getting sleepy at the right time will help you get the sleep you need to maximize your next-day energy levels and perform at your best. But not all melatonin is created equal. You might say that melatonin supplements and the natural melatonin your body makes are as different as night and day. 

Supplements may be beneficial in certain situations — think jetlag or adjusting your sleep schedule — but otherwise, you don't actually need to take melatonin since your body produces it naturally. Plus, the version produced in your own brain is free, and you don’t have to worry about side effects, labels, or dosing confusion. To capitalize on its sleep-enhancing power, it’s vital to be strategic about getting light at the right time of day and to go to bed during your Melatonin Window.

That’s where the RISE app can help. The app predicts when your Melatonin Window is each night and reminds you the best times to get and avoid light exposure based on your own circadian rhythm. This way, you can fall asleep naturally and get all the sleep you need to maximize your energy levels each day. 

All of Your Sleep and Melatonin Questions Answered:

Summary FAQs

How long will I sleep for if I take melatonin?

Melatonin lasts in your body for four to eight hours, but it doesn’t force you to sleep like traditional sleep aids. It simply tricks your brain into thinking it’s sunset, and primes it for sleep. 

Does melatonin make it hard to wake up?

Melatonin supplements don’t have the same hangover effect as traditional sleep aids, but you may feel some drowsiness in the morning if you take too large a dose or take it too close to bedtime.

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

Melatonin can last in your system for four to eight hours, but it all depends on things like age, weight, and the type of supplement you take. Melatonin has a half-life of 20 to 50 minutes, so 10 mg will take longer to wear off than smaller doses. 

Can melatonin make you tired the next day?

Melatonin can make you tired the next day if you take too much the night before or take it too close to bedtime. Try reducing your dose and taking it a few hours before you want to sleep.

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