From Anirva, the maker of Sleep Harmony. This article is general information, not medical advice. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
Melatonin is one of the most familiar sleep supplements, and it raises many questions. How much is right? When should you take it? Is it safe to use every night? Here we look at what melatonin is, what the research shows, how timing matters, how much is in Sleep Harmony, and what to know about safety.
In this article
- Melatonin is your body's timing signal for sleep. Your brain makes it in response to darkness. [1]
- It is mainly a timing aid. Research is strongest for jet lag and for people whose sleep time runs late. [3]
- For general sleep, the effect is modest. A review of 19 trials found that people fell asleep about 7 minutes faster and slept about 8 minutes longer. [4]
- Sleep Harmony contains 5 mg. This is at the top of the range studied for jet lag, where 5 mg helped people fall asleep faster than 0.5 mg. [3][6]
- Short-term use is generally safe. Mayo Clinic notes that people are unlikely to become dependent on melatonin. [5]
What Is Melatonin?
Melatonin is a hormone that your brain makes in response to darkness. It helps set the timing of your 24-hour internal clock and your sleep. [1] Cleveland Clinic explains that your brain releases the most melatonin in darkness and less when you are exposed to light. [2]
A Cochrane review describes melatonin as a hormone that plays a central part in regulating the body's rhythms. [3] This is why it is studied for jet lag. Jet lag happens when your internal rhythms are out of step with the day and night at your destination. [3]
In the United States, melatonin is sold as a dietary supplement, which is regulated less strictly than medicines. [1]
Timing: When Melatonin Is Usually Taken
Because melatonin is a timing signal, when you take it can matter as much as how much you take.
A 2018 trial included 307 people whose natural sleep time ran late. [1] They took melatonin 1 hour before their target bedtime and kept a set bedtime. [1] They fell asleep about 34 minutes earlier on average. [1] The Sleep Harmony directions are two capsules 30 to 60 minutes before bedtime. [6]
Timing can also work against you. The Cochrane reviewers noted that melatonin taken at the wrong time, early in the day, can cause sleepiness and may delay adjusting to local time. [3]
What Does the Research Show?
For general sleep
A 2013 review looked at 19 trials with 1,683 people who had sleep problems that were not caused by another condition. [4] Compared with placebo, melatonin helped people fall asleep about 7 minutes faster and sleep about 8 minutes longer. [4] Overall sleep quality also improved. [4] Trials that lasted longer and used higher amounts showed larger effects on sleep time. [4]
These are modest changes. They fit melatonin's main role as a signal that it is time to sleep.
For jet lag
A Cochrane review of 10 trials found that melatonin can reduce jet lag in adults crossing five or more time zones. [3] Amounts from 0.5 mg to 5 mg worked about equally well. People fell asleep faster and slept better with 5 mg than with 0.5 mg, and amounts above 5 mg were no more effective. [3]
In these trials, people took melatonin close to their target bedtime at the destination, between 10 p.m. and midnight. [3] The reviewers found the benefit was likely to be greater when more time zones were crossed, and smaller for westward flights. [3] They also noted that occasional short-term use appeared to be safe. [3]
For shift work
Results for shift work are less clear. NCCIH reports that one review found workers may sleep about 24 minutes longer during the day, with little change in other parts of sleep. [1]
Study summary
| Study | People | Amount | Main Result |
|---|---|---|---|
| Ferracioli-Oda et al., 2013 (review) [4] | 19 trials, 1,683 people | Varied | About 7 minutes faster to fall asleep and 8 minutes more sleep vs. placebo; better sleep quality |
| Herxheimer & Petrie, 2002 (Cochrane review) [3] | 10 jet-lag trials | 0.5–5 mg | Reduced jet lag; 5 mg helped people fall asleep faster than 0.5 mg; above 5 mg no more effective |
| Sletten et al., 2018 (via NCCIH) [1] | 307 people whose sleep time ran late | — | Fell asleep about 34 minutes earlier with a set bedtime |
How Much Melatonin Is in Sleep Harmony Compared With the Studies?
| Source | Melatonin | Notes |
|---|---|---|
| Sleep Harmony (2 capsules) | 5 mg | From the label [6] |
| Jet-lag trials (Cochrane review) | 0.5–5 mg | 5 mg helped people fall asleep faster than 0.5 mg [3] |
The honest comparison: Sleep Harmony contains 5 mg, the top of the range in the jet-lag review. The Sleep Harmony product page suggests that people who are sensitive to melatonin begin with one capsule. [6] The studies above tested melatonin on its own, so their results do not describe the whole formula.
Forms, Label Accuracy and Quality
Melatonin comes in fast-release and slow-release forms. In the jet-lag review, a 2 mg slow-release form worked relatively poorly. [3] The reviewers suggested that a short, higher peak of melatonin may be more effective for jet lag. [3]
Melatonin products do not always contain the amount on the label. NCCIH describes a 2017 study of 31 melatonin supplements in which most did not match their labels. [1] A 2023 study found that 22 of 25 melatonin gummy products were inaccurately labeled, with 74% to 347% of the stated amount. [1]
This is one reason it helps to choose products from makers who test their products and list exact amounts.
What the Research Does Not Show Yet
NCCIH notes that the possible long-term side effects of melatonin are unclear. [1]
Clinical guidelines state that there is not enough strong evidence on melatonin for long-term sleep problems to recommend its use for that purpose. [1]
A 2025 conference abstract linked long-term melatonin use with heart failure in a health-record study. It was not peer-reviewed, and experts noted that it could show an association, but not cause. [7]
We found no study of melatonin combined with the other Sleep Harmony ingredients.
Safety and Interactions
Mayo Clinic describes melatonin as generally safe for short-term use. [5] It notes that people are unlikely to become dependent on it or find it less effective over time. [5] The most common side effects are headache, dizziness, nausea and daytime drowsiness. [5]
Melatonin can interact with some medicines, including blood thinners, seizure medicines, birth control, blood pressure and diabetes medicines, and medicines that affect the immune system. [5] NCCIH notes that people with epilepsy and people taking blood thinners should use it under medical supervision. [1]
Because melatonin can cause drowsiness, Mayo Clinic advises against driving or using machinery within five hours of taking it. [5] Little research exists on melatonin in pregnancy or breastfeeding. [1]
Melatonin Is One Part of Sleep Harmony
Sleep Harmony combines melatonin, calming herbs and three probiotics in one formula. We chose ingredients that have each been studied for relaxation and sleep.
Sleep Harmony has not been clinically tested as a finished product. For this reason, we cannot say how its ingredients work together. The studies in this article tested melatonin by itself, and their results describe melatonin alone.
If you take Sleep Harmony, you are not relying on melatonin alone. It is one of 14 ingredients in each serving.
Melatonin is generally safe for short-term use, and people are unlikely to become dependent on it. [5] Because it can cause drowsiness, Mayo Clinic advises against driving within five hours of taking it. [5] People with epilepsy, people taking blood thinners, and anyone who is pregnant, nursing or taking other medicines can check with a doctor or pharmacist before use.
If You Are Deciding
Melatonin is meant to go alongside good sleep habits. Mayo Clinic suggests using it together with lifestyle changes rather than on its own. [5] Cleveland Clinic suggests a steady sleep schedule, less caffeine and alcohol, and a cool, dark bedroom. [8]
If you would like to try Sleep Harmony, the directions are two capsules 30 to 60 minutes before bedtime. If you are sensitive to melatonin, the product page suggests beginning with one capsule. [6]
The Short Version
Melatonin is your body's signal that it is time to sleep. Research is strongest for timing problems such as jet lag, and the effect on general sleep is modest. Sleep Harmony contains 5 mg, the top of the range studied for jet lag. Short-term use is generally safe, and people are unlikely to become dependent on it.
Frequently Asked Questions
Does melatonin help you sleep?
Does melatonin help with jet lag?
Is slow-release melatonin a better choice?
How much melatonin should I take?
When should I take melatonin?
Is melatonin habit-forming?
Is it safe to take melatonin every night?
Why do melatonin doses vary so much?
What are the side effects of melatonin?
Does melatonin interact with medicines?
References
- National Center for Complementary and Integrative Health. Melatonin: what you need to know. Last updated May 2024.
- Cleveland Clinic. Melatonin: what it is, what it does and how it works. Reviewed April 28, 2025.
- Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database Syst Rev. 2002;(2):CD001520. doi:10.1002/14651858.CD001520. PMID: 11279722.
- Ferracioli-Oda E, Qawasmi A, Bloch MH. Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One. 2013;8(5):e63773. doi:10.1371/journal.pone.0063773. PMID: 23691095.
- Mayo Clinic Staff. Melatonin side effects: what are the risks? Mayo Clinic. December 16, 2025.
- Anirva. Sleep Harmony with Probiotics: Supplement Facts label and product page. (accessed September 30, 2026).
- Science Media Centre. Expert reaction to conference abstract on association between long-term melatonin supplementation and incidence of heart failure in patients with insomnia. November 2025.
- Umeda N (expert). Does magnesium help you sleep better? Cleveland Clinic Health Essentials. September 4, 2026.
14 ingredients, including 5 mg of melatonin
Sleep Harmony is a nightly two-capsule supplement that pairs melatonin with magnesium, L-theanine, ashwagandha and three probiotics. Every ingredient is listed on the label.
See Sleep Harmony
