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How Long Does it Take For Melatonin To Work?

Jill Johnson

Reviewed by Jill Johnson, FNP

Written by Geoffrey Whittaker

Published 04/25/2022

Updated 04/26/2022

It’s 1 a.m., you’re tired, you have a long day tomorrow and the tasks on your to-do list are giving you anxiety. You want to be asleep — you need to be asleep. And rather than spend the next few hours tossing and turning, you’re thinking about taking melatonin for your insomnia problem. 

How long will it take to put you to sleep?

It’s a question many of us have asked before: how long does it take for melatonin to work, and is there a chance it will knock me out immediately?

The answer might surprise you with both good and bad news.

Melatonin is a synthetic dietary supplement that mimics the endogenous hormone of the same name. 

Your body makes natural melatonin in response to darkness — when you see that it’s getting dark outside, your pineal gland uses an amino acid called tryptophan as a building block to produce melatonin.

When melatonin exits the pineal gland, it hits your circulatory system and begins cueing your body to enter the sleep phase of its circadian rhythm. In other words, it makes you feel sleepy.

Lest you think melatonin is a one-trick pony, don’t be fooled: everything from pain and mental health, heart disease to cancer suppression, reproductive functions and even your blood sugar are affected by proper melatonin function.

The FDA, by the way, does not regulate nutritional supplements, and it’s important to understand that there is no FDA approval for melatonin on any level. 

Nevertheless, the American Academy of Family Physicians and other medical organizations consider it safe and effective.

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Melatonin effectiveness will vary from person to person based on body size, metabolism and other factors, but one study found that using supplemental melatonin made people fall asleep around seven minutes earlier, sleep for eight minutes longer and increase the relative quality of sleep in the process.

Findings on when to take melatonin, however, haven’t led to a definite understanding of the timing. Generally, the Centers for Disease Control and Prevention (CDC) suggests taking melatonin between one and two hours before you’re intending to fall asleep, it will last about four hours before it's 95 percent absorbed by your body (if you’re reading this at two in the morning, our condolences).

This is different from the data shown by people with something called delayed sleep-wake phase disorder (DSWPD). A 2016 study found that people with DSWPD fell asleep around 22 minutes faster than without melatonin.

And since melatonin supplements have little in the way of regulation, the best and most accurate information we can give you is simply to follow the directions on the packaging of whatever melatonin you purchase, and find out how quickly it works on your own through testing.

Speaking of products, there are many to consider. Melatonin is available in a variety of forms: liquids, tablets, rectal suppositories and patches all function similarly, and it may also be formulated as immediate or extended-release.

You can take it in a variety of ways and, according to the research available, it doesn’t make a huge difference. Learn more in this guide: how long does melatonin last?

Studies have shown that even extreme doses in the short term carry relatively mild common side effects like nausea, sleepiness, dizziness and headaches. There’s data to show that even in the long term, the negative effects of melatonin are mostly mild and similar to what we’ve mentioned above. We've also written exclusively about more of the melatonin side effects you might experience.

One note: you shouldn’t take melatonin in the morning or middle of the day unless you’re a night owl working night shifts. Contrasting your natural melatonin production with daytime melatonin leads to daytime sleepiness.

Things change a bit if you or the sleepless patient in question are on the younger side. 

Studies haven’t thoroughly examined the long-term effects of melatonin use for children and adolescents, and since this group is still in the process of forming habits and developing, it may be worth a second thought before you say goodnight to an elementary schooler every night with a melatonin gummy — at least, not until we know more.

The fact is that insomnia is about more than missing bedtime and feeling drowsy the next day. Insomnia has been linked with diabetes and blood pressure issues, as well as reduced immune system function.

The general class of circadian rhythm sleep disorders may respond to melatonin, but over-the-counter medications may not be enough. In these cases, the National Institutes of Health suggests examining your habits and considering the following changes:

  • Turn your bedroom into a cool, quiet and dark environment ideal for sleeping.

  • Limit exposure to blue lights, reduce overhead lights and generally avoid these visual sources of sleep disturbances.

  • Skip the late-night meals to avoid broken sleep.

  • Don’t drink a lot of water or other beverages before bed (especially alcohol).

  • Treat your stress to reduce late-night anxiety.

  • Avoid caffeine before bed and smoking in general.

  • Once you’re on a routine, stick to it — let your body expect sleep at the same time every night.

Lifestyle changes aside, there’s more to good sleep than what you do a couple hours before bed. You might consider therapeutic practices like cognitive behavioral therapy to learn how to prepare your mind for sleep each night.

Your healthcare provider might also suggest prescription drugs like benzodiazepines, which function like sedatives. These can be used safely for short periods of time, but as they are considered habit-forming, they should be avoided as a long-term solution. 

Sleep patterns get screwed up for all types of reasons, and everyone deals with it at some point. Melatonin may be a good option for short- or long-term bouts with insomnia or late-night restlessness, and is generally considered safe.

But if you’re experiencing persistent issues getting enough restful sleep, you might benefit from speaking with your healthcare provider

Speaking with a professional about getting the appropriate hours of sleep may lead to more helpful information about your health. 

You may learn that you’re dealing with additional issues, like a circadian rhythm disorder or sleep apnea. In these cases, a healthcare professional is uniquely qualified to help you explore your treatment options. 

5 Sources

  1. U.S. Department of Health and Human Services. (n.d.). Insomnia. National Heart Lung and Blood Institute. Retrieved March 1, 2022, from
  2. Savage RA, Zafar N, Yohannan S, et al. Melatonin. [Updated 2021 Aug 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:
  3. Centers for Disease Control and Prevention. (2020, March 31). Module 6. improving your sleep and alertness, sleep aids and stimulants, OTC meds. Centers for Disease Control and Prevention. Retrieved March 1, 2022, from
  4. U.S. Department of Health and Human Services. (n.d.). Melatonin: What you need to know. National Center for Complementary and Integrative Health. Retrieved February 28, 2022, from
  5. ​​Andersen, L. P., Gögenur, I., Rosenberg, J., & Reiter, R. J. (2016). The Safety of Melatonin in Humans. Clinical drug investigation, 36(3), 169–175.
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Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references. See a mistake? Let us know at [email protected]!

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

Jill Johnson, FNP

Dr. Jill Johnson is a board-certified Family Nurse Practitioner and board-certified in Aesthetic Medicine. She has clinical and leadership experience in emergency services, Family Practice, and Aesthetics.

Jill graduated with honors from Frontier Nursing University School of Midwifery and Family Practice, where she received a Master of Science in Nursing with a specialty in Family Nursing. She completed her doctoral degree at Case Western Reserve University

She is a member of Sigma Theta Tau Honor Society, the American Academy of Nurse Practitioners, the Emergency Nurses Association, and the Air & Surface Transport Nurses Association.

Jill is a national speaker on various topics involving critical care, emergency and air medical topics. She has authored and reviewed for numerous publications. You can find Jill on Linkedin for more information.

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