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Sleep Doctor Explains What Melatonin Does and Doesn’t Do

Melatonin — either the kind your body makes or the kind you buy in a bottle — helps you feel drowsy and gets your body ready for sleep. Here’s how.
Written by
Jeff Kahn, M.S., Rise Science Co-Founder
Reviewed by
Jamie Zeitzer, PhD, Rise Science Scientific Reviewer
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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 getting ready to go to sleep taking melatonin supplements

What Does Melatonin Do? The Key Facts

  • Melatonin is a hormone that helps keep your circadian rhythm (your body clock) in check and prepares your body for sleep. 
  • As a supplement, melatonin can shift the timing of your circadian rhythm, so you can fall asleep earlier or later than you usually would. It’s not that effective as a traditional sleep aid, though.
  • The RISE app can tell you the best time to take melatonin supplements (based on your own body clock), when to go to sleep (based on when your body’s rate of melatonin production is at its highest), and guide you through 20+ sleep hygiene habits to boost your own production of melatonin.

You may have seen melatonin in your local drugstore. It’s marketed as an over-the-counter supplement to help you sleep. And while that is technically true, it doesn’t work like a traditional sleep aid.

Melatonin can shift the timing of your circadian rhythm and can help you sleep at a time you usually wouldn’t, but it’s not that effective at helping you fall asleep faster at your usual bedtime. 

Below, we dive into what melatonin does, how to harness your natural supply of the hormone, and outline the three times you might consider taking it in supplement form.

Advice From a Sleep Doctor

Advice From a Sleep Doctor

“Your natural melatonin hormone helps your body get ready for sleep and keeps your sleep schedule running smoothly.

When you take a melatonin supplement, melatonin shifts the timing of your body clock, helping you sleep earlier or later than usual.

While it’s effective for jet lag, it’s not that good at helping you fall asleep faster at bedtime, and it may not be the best treatment for sleep problems like insomnia,” says Dr. Chester Wu, Rise Science sleep advisor and medical reviewer, and a sleep doctor who’s double board certified in psychiatry and sleep medicine.

What Is Melatonin? 

Melatonin is a hormone that keeps your circadian rhythm, your internal body clock, in check and it helps your body get ready for sleep.

If all is going well, you’ll have low melatonin levels during the day and high melatonin levels at night.

Graph showing melatonin production over day and night
Melatonin levels over the day and night. Source: https://sites.psu.edu/lifeitmoveson/2018/01/26/sleep-external-influences/

Melatonin can also be made in a lab or from animal glands and packaged into everything from gummies to sprays, creams to capsules. In supplement form, melatonin can help you feel sleepy at times you usually wouldn’t — like during the day if you work night shifts, or earlier or later than usual if you’ve crossed time zones or are trying to move your sleep schedule. 

The US Food and Drug Administration (FDA) classifies melatonin as a dietary supplement, so there are no strict rules or dosage guidelines. 

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What Does Melatonin Do?

Melatonin helps your body get ready for sleep. Supplements can do the same, making you feel drowsy and changing the timing of your circadian rhythm. 

If you take melatonin in the morning, you can push back your circadian rhythm and fall asleep later than usual. If you take melatonin about four to five hours before bed, you can pull your circadian rhythm forward and fall asleep earlier than usual. 

This is useful for: 

  • Getting over jet lag
  • Adjusting to shift work 
  • Shifting your sleep schedule

Melatonin doesn’t force you to sleep like a traditional sleep aid. If you take it before bed, it may only help you get a few minutes more sleep or not make that much of a difference at all. 

Melatonin is sometimes prescribed by a healthcare provider for circadian rhythm disorders like delayed sleep phase disorder. It may not be that useful for insomnia, though. 

The American Academy of Sleep Medicine doesn’t recommend using melatonin to treat insomnia. And research shows melatonin can help people with sleep disorders reduce their sleep onset latency (how long it takes to fall asleep), but only by seven minutes compared to a placebo.

More research is needed, but melatonin supplements may help those with high blood pressure, attention deficit hyperactivity disorder (ADHD), anxiety before surgery, insulin resistance, and cancer. 

How Does Melatonin Work? 

Melatonin works by priming your body for sleep, either naturally or when you take a supplement. 

In Your Body 

As long as it’s dim enough, your body starts producing melatonin about two hours before your typical bedtime. This moment is what sleep scientists call the dim light melatonin onset (DLMO). 

This is when your suprachiasmatic nucleus (SCN) — a group of neurons in your brain that act as your central body clock — tells your pineal gland to start producing melatonin. 

Scientists believe that as the amount of melatonin in your system rises, the hormone suppresses SCN activity, leading to reduced wake promotion from neuromodulators in your brain. Come morning, melatonin levels decrease.

In Supplement Form 

When you take a melatonin supplement, it doesn’t force your body to sleep like traditional sleeping pills do. 

Melatonin supplements work as a chronobiotic, or something that can shift the timing of your circadian rhythm. This is helpful for moving your sleep schedule, though it does so quite slowly. Melatonin can also act similarly to a hypnotic, or something that induces sleep, by decreasing alertness — though this only happens when you take it during the daytime. When you take melatonin during the day to help you sleep, it works by blocking a signal in your body that keeps you alert, allowing natural sleep to occur. This is different from traditional sleeping pills, which create a state of unconsciousness that doesn't quite mirror normal, healthy sleep.

Melatonin can last in your system for more than 12 hours, depending on your age and the dose and type of supplement you take. How long melatonin lasts exactly can influence how it works. For example, if melatonin lasts a long time and you wake up with high levels of it in your system, you may feel groggy and it may push back your circadian rhythm, making it harder to sleep the next night.

However, you don’t need to take melatonin every night to fall asleep. Supplements work best when you want to sleep when your natural levels of melatonin are low, like during the day. 

What Are Melatonin Side Effects? 

The common side effects of melatonin supplements include:

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

Less common but possible side effects of melatonin include:

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

There’s a lot we still don’t know about long-term effects, and the National Center for Complementary and Integrative Health says, “there’s not enough information yet about possible side effects to have a clear picture of overall safety.”

There’s one side effect you don’t have to worry about, though. Melatonin isn’t considered addictive

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Does Melatonin Make It Harder to Wake Up? 

Melatonin can make it harder to wake up by making you feel groggy or by pushing back your circadian rhythm, making your body want to sleep in later than usual

This can happen if you have high levels of melatonin in your system from taking a large dose of melatonin before bed, a slow-release supplement too close to bedtime, only sleeping for a short period of time, or taking melatonin during the night. 

You may also find it harder to wake up if you take a low dose of melatonin in the morning as this can push back your circadian rhythm the next night.

If you find it harder to wake up after taking melatonin, and you’re not trying to shift your circadian rhythm back, try taking a smaller dose, taking a fast-release supplement, or taking it earlier in the day, not at bedtime. 

We’ve covered when to take melatonin before bed here.

There are no set guidelines, but in general, here’s when and how much melatonin to take

Take melatonin in the morning to fall asleep later and about four to five hours before bed to fall asleep earlier than usual.  

  • To get over jet lag: Take 0.3 mg to 1 mg, depending on your direction and duration of travel. Take melatonin a few days before your flight and until adjusted to your destination.
  • To shift your sleep schedule: Take 0.3 mg to 1 mg, depending on which direction you want to shift your sleep schedule in. Even smaller doses may be effective. 
  • To adjust to shift work: Take 0.3 mg to 1 mg of melatonin, but consider other treatments, like light therapy, which may be safer. You don’t want to feel any sleepiness during your shift. 

You probably don’t need high doses of melatonin. Most experts recommend 0.3 mg to 1 mg doses of melatonin and most clinical trials look at 2-mg doses, so it’s not clear how safe larger doses are. 

Plus, your body only produces about 10 to 80 micrograms of melatonin a night (about 0.01 mg to 0.08 mg), so the 5, 10, and 20 mg doses of melatonin you can buy are thousands of times higher than your natural levels.

And you don’t need to take supplements for long. Melatonin is recommended for short-term use. Take melatonin until you’ve adjusted and then rely on good sleep hygiene to help you keep up your new sleep pattern. More on that soon.

You can learn how much melatonin to take for jet lag here.

To fall asleep earlier, RISE can tell you the right time to take melatonin supplements based on your own circadian rhythm. 

RISE app screenshot showing melatonin supplement reminder
The RISE app can tell you when to take melatonin supplements.

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

Do Melatonin Supplements Work? 

Melatonin supplements may work well at changing the timing of your circadian rhythm. They can help you feel sleepy at a time you usually wouldn’t, so they can be effective at treating jet lag, helping shift workers adjust to new schedules, and helping you move your sleep schedule. 

For example, research shows a 0.5-mg dose of melatonin can shift your circadian rhythm earlier. And research shows 1.8 mg of melatonin can help people sleep out of sync with their circadian rhythms, like during the day.

Melatonin doesn’t work that well if you take it right before bed to try and fall asleep faster at your usual bedtime. Your natural melatonin levels will already be high at this time.

There is research suggesting melatonin may not work long-term. And there’s even research that states melatonin may not be that effective for jet lag, adjusting to shift work, or to fall and stay asleep. 

We cover why melatonin may not work for you here.

Heads-up: Get medical advice before taking melatonin if you’re pregnant, breastfeeding, a transplant recipient, on medication (like immunosuppressants or oral contraceptives), or have a medical condition, including diabetes, high blood pressure, seizure disorders, bleeding disorders, depression, or insomnia. 

You don’t need to take melatonin supplements to fall asleep. With the right behaviors, your body can make all the melatonin it needs to fall asleep. 

If you are using supplements, though, we recommend Thorne and USP tested.

Make the Most of Your Body’s Natural Melatonin 

Focus on improving your sleep hygiene. This is the set of behaviors you can do throughout the day to get better natural sleep. One of the most important behaviors is timing your light exposure right as this has the biggest impact on your melatonin levels. 

Here’s what good sleep hygiene looks like: 

  • Get natural light in the morning and throughout the day (light suppresses melatonin production and morning light sets your body up to make melatonin later that evening) 
  • Dim the lights and put on blue-light blocking glasses 90 minutes before bed (so light doesn’t suppress or delay melatonin production before bed)
  • Keep your bedroom dark, cool, and quiet
  • If you wake up in the night, keep the lights off or low 
  • Stop drinking three to four hours before bed (even moderate drinking before bed suppresses melatonin)
  • Avoid caffeine, vigorous exercise, and large meals too close to bedtime 
  • Keep a regular sleep pattern every day of the week (a regular sleep schedule helps your circadian rhythm sync up with the light-dark cycle, which means your body can produce melatonin at the right times for sleep)

RISE can remind you when to do 20+ sleep hygiene habits based on your circadian rhythm each day. These habits can help you fall asleep faster and reduce sleep disturbances at night. 

Learn what you need to know about increasing melatonin naturally here.

RISE app screenshot showing sleep hygiene habit reminders
The RISE app can help you improve your sleep hygiene.


Once you’re doing things to make sure your brain can make enough melatonin for healthy sleep, it’s time to make the most of it. 

RISE can predict the timing of your Melatonin Window. This is what we call the roughly one-hour window of time when your body’s rate of melatonin production is at its highest. Go to sleep within this window and you’ll have a much easier time falling asleep — no sleep aid required. 

RISE users agree: 

“If I go to sleep according to my schedule, within my Melatonin Window, I am guaranteed to satisfy my sleep needs without any additional sleep aids, supplements, or medications. I am blown away by the accuracy and effectiveness of RISE.” Read the review

Expert tip: Sleep hygiene is the science-backed way to optimize your natural melatonin levels for better sleep, but better sleep starts with knowing how much of it you need to begin with. Check RISE to find out how much sleep you need. It varies from person to person. For example, when we looked at how much sleep 1.95 million RISE users aged 24 and over needed, we found it ranged from five hours to 11 hours 30.

The RISE app can tell you how much sleep you need
How much sleep RISE users need.

Let Your Body’s Melatonin Do Its Thing 

The hormone melatonin helps us fall asleep, but you don’t need to take a supplement form to get the sleep you need each night. By maintaining good sleep hygiene, your brain can produce all the melatonin it needs. 

Supplements can help when you need to shift your circadian rhythm, like when traveling across time zones. 

The RISE app can tell you the exact time to do 20+ sleep hygiene behaviors. Plus, the app can show you when your Melatonin Window is each night, so you can line up your bedtime with when your natural levels are high. 

This can make a difference in no time — 80% of users get more sleep within five days.


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