What Does Melatonin Do? The Misunderstood Sleep Hormone

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.
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Jeff Kahn, M.S., Rise Science Co-Founder
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Woman getting ready to go to sleep taking melatonin supplements

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

Melatonin isn’t just something you can buy, either. It’s a natural hormone made in our bodies to help us sleep and keep your sleep-wake cycles regulated. And while supplements are useful in some cases, they shouldn’t be something you turn to night after night to fall asleep or to solve all your sleep problems. By learning how to optimize your natural production, you can get all the melatonin you need to fall asleep easily, stay asleep all night, and have plenty of energy each day. 

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

What is Melatonin?

Melatonin is a hormone that’s made in your brain to help you feel sleepy and to get your body ready for sleep. It also keeps your sleep schedule in sync with your circadian rhythm, your internal body clock that’s running on a roughly 24-hour cycle. 

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 in the day if you’re battling jetlag or trying to move your sleep schedule. 

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


What Does Melatonin Do?

Melatonin gets your body ready for sleep. It lowers your body temperature, blood pressure, stress hormones, and how alert you feel, helping you drift off. 

Supplements can do the same, lowering your body temperature and making you feel drowsy and they can change the timing of your body clock. Depending on when you take them and how much you take, you may feel drowsy after 20 minutes, or it may take a few hours to feel the effects.

How Does Melatonin Work?

So, now you know melatonin helps you fall asleep, how exactly does it work? 

In Your Body 

The suprachiasmatic nucleus (SCN) is a group of neurons in the hypothalamus part of your brain. This is the master clock of your circadian rhythm and is influenced by light through the retina and optic nerve. 

As long as the light’s dim enough, the SCN will tell the pineal gland in your brain to start producing melatonin two hours before your biological bedtime. This moment is what sleep scientists call the dim light melatonin onset (DLMO).

As the amount of melatonin in your system rises, your body temperature, blood pressure, stress hormones, and alertness levels lower, getting you ready for sleep. 

Melanopsin is a photopigment in our eyes that, when activated light, suppresses melatonin synthesis. So, when you wake up, light exposure suppresses melatonin production, signaling to your brain that it’s daytime and resetting your circadian rhythm. 

In Supplement Form 

When you take a melatonin supplement, it doesn’t force your body to sleep like traditional sleeping pills do. Instead, it tricks the brain into thinking it’s sunset, making it wind down and get ready for sleep. 

Your body temperature and alertness levels are lowered and, depending on when you take it, you’ll find it easier to fall asleep earlier or later than usual. That’s because melatonin supplements work as a chronobiotic, or something that can shift the timing of your circadian rhythm. Things like when your body produces its own melatonin (to help you sleep), cortisol (to wake you up), and when it wants to sleep and be awake can be earlier or later. 

Melatonin will last in your system for four to eight hours. However, you don’t need to take melatonin every night to fall asleep. They work best when you want to sleep when your natural levels of melatonin are low. 

How Do I Boost My Body’s Melatonin?

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.

Your body can make all the melatonin it needs for natural sleep, you just need to let it. Unfortunately, melatonin production is easily disrupted by light exposure. 

One study found exposure to room light in the hours leading up to bedtime resulted in melatonin being produced later than usual and for a shorter duration of time — about 90 minutes shorter to be exact. The researchers also found exposure to room light during usual sleeping hours suppressed melatonin by more than 50%. 

If you get too much light exposure in the evenings — think from your phone, television, or bright overhead lighting — you’ll suppress melatonin production, making it much harder to fall asleep when you want to. You don’t need to spend your evenings in pitch black, though. The study compared room light to dim light, so all you need to do is make your evenings dimmer. 

Here’s how to boost natural melatonin production: 

  • Get natural light in the mornings: Aim for at least 10 minutes outside in natural light, or 30 minutes if it’s cloudy out or you’re sitting by a window. This will suppress melatonin production, telling your brain it’s time to be awake. It’ll also boost your body’s production of serotonin, which about 12 hours later will be converted into melatonin. 
  • Get natural light throughout the day: Four to five hours of natural light during the day may make you less sensitive to bright lights in the evening. Get out for walks, exercise, and work by a window if possible. 
  • Dim the lights in the evenings: As you now know, it needs to be dim for your brain to start making melatonin. Switch from overhead lighting to lamps to make things darker. To stop blue light from your electronics impacting melatonin production, put on blue-light blocking glasses 90 minutes before bed. 
  • Make your bedroom as dark as possible: Use blackout curtains and an eye mask to avoid sleep disturbances caused by light. And don’t turn on the lights if you wake up during the night. Use your phone flashlight if you need to use the bathroom, for example. 

These behaviors come under something called sleep hygiene, which is a set of behaviors you can do throughout the day to help you sleep at night. Beyond being strategic with light, you should also pay attention to other sleep hygiene habits like avoiding late-night alcohol — even moderate drinking suppresses melatonin

The RISE app can tell you the exact times to do things like get light, avoid light, and have your last alcoholic drink based on your individual circadian rhythm. 

Once you’re doing things to make sure your brain can make all the melatonin it needs for healthy sleep, it’s time to harness it. In the RISE app, you can see your Melatonin Window. This is the roughly one-hour window of time when your brain will be making the most melatonin it will all night. Go to sleep in this window and you’ll have a much easier time falling asleep — no sleep aid required. 

When Should I Take Melatonin Supplements?

RISE app screenshot showing you when to take melatonin supplements.g
The RISE app will tell you when to take melatonin supplements.

Melatonin is useful when you need to sleep when your body isn’t naturally producing high levels of melatonin. This would include when you’re: 

  • Battling jet lag 
  • Moving your sleep schedule 
  • Adjusting to shift work 

While melatonin isn’t addictive and there’s no risk of overdosing, there aren’t many clinical trials on the long-term effects. In fact, most studies are only one to seven days long. The good news is, short-term use of melatonin does appear to be safe. 

If you do turn to melatonin supplements, we recommend Thorne and USP tested. The RISE app can tell you when exactly to take melatonin supplements to help you feel sleepy come bedtime. 

Here’s what you need to know about when to take supplements: 

Jet lag 

It all depends on if you’re flying east or west, and so whether you’re trying to bring your sleep schedule forward to push it back. 

  • 0.5 mg to 5 mg doses have been shown to be effective
  • Start taking them a few days before your flight, and then until you’re adjusted in your new time zone 

Sleep schedule 

If you've got delayed sleep phase disorder or you’re a night owl trying to become a morning person, melatonin can help to shift your sleep pattern earlier. 

  • 1 mg doses may be enough to be effective 
  • Take them short term until you’re adjusted 

Shift work 

  • Try 0.3 mg to 5mg doses 
  • Take them short term until you’re adjusted to your new sleep-wake times 

While some studies show shift workers taking melatonin report increased sleep quality (even though sleep scientists don’t agree on a definition for sleep quality), not everyone agrees melatonin is the answer for them. The National Institutes of Health (NIH) says studies are small and inconclusive. Light therapy may be a better option here. 

We’ve covered more about how much melatonin to take here.  

When Shouldn’t I Take Melatonin?

Melatonin supplements aren’t the answer for everyone. They may not be suitable for those with sleep disorders like insomnia. The American Academy of Sleep Medicine is investigating the safety of melatonin and, for now, it’s recommending those with insomnia avoid it. You should seek medical advice if this is you to find alternative treatments. 

Speak to your health care provider before taking melatonin if you’re pregnant, breastfeeding, or if you’re taking certain medications like epilepsy drugs, blood thinners, immunosuppressants, or oral contraceptives. 

If you’re a normal sleeper, there may not be a need to take melatonin at all. Research suggests melatonin decreases sleep onset latency (the time it takes to fall asleep) and increases sleep efficiency (the time you spend in bed sleeping) in normal sleepers, but the amounts were so small they were deemed clinically insignificant. So, if you’re a normal sleeper and have the occasional bad night’s sleep, it’s far better to focus on good sleep hygiene going forward.

We’ve covered other times when you shouldn’t take melatonin here. 

Let Your Body’s Melatonin Do Its Thing

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

The RISE app can tell you the exact time to do sleep hygiene behaviors like getting and avoiding bright light to boost your melatonin. Plus, the app can show you when your Melatonin Window is each night, so you can line up your bedtime with when levels are their highest. This way, you can fall asleep easily, stay asleep all night, and be at your best each day. 

All of Your Sleep and Melatonin Questions Answered:

Summary FAQs

What does melatonin do when you take it?

Melatonin tricks your brain into thinking it’s sunset, priming it for sleep. You may feel sleepiness 20 minutes or a few hours later and, depending on when you take it, be able to fall asleep at an earlier or later time than usual. 

How does melatonin impact sleep?

Melatonin tricks your brain into thinking it’s sunset, getting it ready for sleep a few hours later and helping you fall asleep. It shifts your circadian rhythm so you can either fall asleep earlier or later than usual.

Does melatonin make it hard to wake up?

Melatonin shouldn’t make it hard to wake up in the same way traditional sleep aids do. If you do feel sleepy the next morning, it may be due to a high dose. Try taking a smaller dose of melatonin earlier in the day next time.

Side effects of melatonin

The side effects of melatonin include headaches, nausea, dizziness, depression, tremors, low blood pressure, allergic reactions, and unintended daytime drowsiness.

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Try 7 days free

The power behind your next best day

RISE makes it easy to improve your sleep and daily energy to reach your potential

RISE app iconApp store icon