What Does Melatonin Do, and How Does It Work?

Melatonin is a hormone naturally produced in our bodies. It’s most often thought of as a “sleep hormone” due to its role in setting our circadian rhythm. But, melatonin doesn’t exactly make us fall asleep so much as it helps signal our bodies to wind down and feel tired (thereby making it easier to fall asleep).

While melatonin is involved in sleep, it also has much more to offer, as you’re about to find out.

What Does Melatonin Do?

In addition to promoting sleep, melatonin also impacts[1,2]:

• Blood pressure
• Blood sugar
• Body weight
• Hormone levels
• Body temperature
• Immune function

The multi-faceted hormone has also been shown in research to offer antioxidant, anti-inflammatory and body recomposition effects as well.[3,4]

How Does Melatonin Work?

Melatonin production starts with the essential amino acid (EAA) tryptophan, which is converted into serotonin in the brain. A portion of this serotonin reaches the pineal gland, where it undergoes a cyclic, light-dependent process to be converted into melatonin.[1]

It regulates the body's sleep-wake cycles through interactions with the suprachiasmatic nucleus (SCN) of the hypothalamus and the retina, encouraging sleep and inhibiting wake-promoting signals.[1]

Melatonin and Sleep

Melatonin plays an important role in sleep, and sleep has a tremendous impact on your daily performance and productivity as well as your overall health, well-being and longevity. However, significant portions of the population do not consistently get enough quality sleep. This is due, in part, to several lifestyle factors that impair melatonin production at night, including[5,6]:

• Blue light exposure (TVs, tablets, laptops, smartphones, etc.)
• Caffeine consumption
• Alcohol consumption
• Smoking
• Shift work
• Aging

Over time, disrupted melatonin production and poor sleep quality can lead to misalignment of your circadian rhythm, which itself is known to lead to metabolic disorders and mental health conditions, including depression.[7]

In fact, research shows that a single night of light exposure during sleep acutely impacts measures of insulin resistance.[8]

The good news is that melatonin supplementation can be effective for improving sleep quality and decreasing sleep latency.[9,10]

Melatonin and Fat Loss

Not only does melatonin help with sleep, it may also support weight loss and body recomposition goals. Human and animal studies find that melatonin may help decrease body weight and abdominal fat without reducing calorie intake (“dieting”) or increasing physical activity levels (“exercising”).

Melatonin supports body recomposition by increasing the amount of “brown” fat and boosting brown adipose tissue (BAT) activity. This helps increase fat burning and energy expenditure.[11,12,13,14]

Moreover, a year-long, placebo-controlled study in postmenopausal women found that melatonin supplementation (1 or 3 mg per night) improved body composition and lipid metabolism. The women supplementing with melatonin lost body fat and an increased lean mass. Researchers also noted a trend towards higher levels of adiponectin -- a hormone that regulates glucose levels, lipid metabolism, and insulin sensitivity.[15]

All of this is to say that if you’re interested in a leaner, fitter, and overall higher quality of life, sleep is a must.

Melatonin and Brain Health

Thanks to its potent antioxidant and anti-inflammatory properties, melatonin has garnered increased interest for its role in cognitive performance and long-term brain health.

In the brain specifically, long-term oxidative stress kickstarts several processes that play a pivotal role in the pathology of Alzheimer’s Disease. Prolonged oxidative stress can also induce apoptosis in neurons and trigger neuroinflammation.[16]

Melatonin combats oxidative stress and enhances the activities of antioxidant enzymes, including glutathione peroxidase and superoxide dismutase in neurons.[16,17]

Is Melatonin Safe?

Melatonin has been extensively studied and found to have a high safety profile. Typically melatonin supplements are taken between 0.1-10mg, but higher doses have been studied in humans.[18,19]

Side effects are minimal and may include grogginess, fatigue and daytime sleepiness.

Ideally, you would find the lowest effective dose of melatonin for your needs as higher doses of melatonin don’t always equate to better sleep outcomes.

The Best Melatonin Supplement

Melatonin is widely available in both standalone supplements as well as more comprehensive formulas.

Our preferred melatonin supplements are Beauty Dream PM and Recharge PM, both of which include a research-supported dose.

To further support healthy melatonin levels and promote deeper sleep, we suggest:

• Maintaining a consistent bedtime
• Limiting blue light exposure at least two hours before bed
• Keeping your bedroom cool and dark
• Wearing comfortable clothing to bed
• Taking a warm shower/bath before bed
• Reading/journaling/meditating

References

1. Savage RA, Zafar N, Yohannan S, et al. Melatonin. [Updated 2024 Feb 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from:https://www.ncbi.nlm.nih.gov/books/NBK534823/
2. Lok R, van Koningsveld MJ, Gordijn MCM, Beersma DGM, Hut RA. Daytime melatonin and light independently affect human alertness and body temperature. J Pineal Res. 2019 Aug;67(1):e12583. doi: 10.1111/jpi.12583. Epub 2019 May 9. PMID: 31033013; PMCID: PMC6767594.
3. Guan Q, Wang Z, Cao J, Dong Y, Chen Y. Mechanisms of Melatonin in Obesity: A Review. Int J Mol Sci. 2021 Dec 25;23(1):218. doi: 10.3390/ijms23010218. PMID: 35008644; PMCID: PMC8745381.
4. Carrillo-Vico A, Lardone PJ, Alvarez-Sánchez N, Rodríguez-Rodríguez A, Guerrero JM. Melatonin: buffering the immune system. Int J Mol Sci. 2013 Apr 22;14(4):8638-83. doi: 10.3390/ijms14048638. PMID: 23609496; PMCID: PMC3645767.
5. Arendt J, Aulinas A. Physiology of the Pineal Gland and Melatonin. [Updated 2022 Oct 30]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Table 1. [Factors Influencing Human Melatonin Secretion and Production (),()]. Available from:https://www.ncbi.nlm.nih.gov/books/NBK550972/table/neuroendo_pinealmel.T.factors_influencin/
6. Lockley SW, Brainard GC, Czeisler CA. High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light. J Clin Endocrinol Metab. 2003 Sep;88(9):4502-5. doi: 10.1210/jc.2003-030570. PMID: 12970330.; Chang, A. M., Aeschbach, D., Duffy, J. F. & Czeisler, C. A. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proc. Natl. Acad. Sci. U.S.A. 112, 1232–1237 (2015).
7. Jagannath A, Taylor L, Wakaf Z, Vasudevan SR, Foster RG. The genetics of circadian rhythms, sleep and health. Hum Mol Genet. 2017 Oct 1;26(R2):R128-R138. doi: 10.1093/hmg/ddx240. PMID: 28977444; PMCID: PMC5886477.
8. I Mason, D Grimaldi, R G Malkani, K J Reid, P C Zee, 0117 Impact of Light Exposure during Sleep on Cardiometabolic Function, Sleep, Volume 41, Issue suppl_1, April 2018, Page A46,https://doi.org/10.1093/sleep/zsy061.116
9. Iomski A. Melatonin Improves Sleep in Patients With Circadian Disruption. JAMA. 2018;320(8):749. doi:10.1001/jama.2018.10903
10. Sletten TL, Magee M et al. Efficacy of melatonin with behavioral sleep-wake scheduling for delayed sleep-wake phase disorder: A double blind, randomized clinical trial (2018). Efficacy of melatonin with behavioral sleep-wake scheduling for delayed sleep-wake phase disorder: A double blind, randomized clinical trial. PLOS Medicine 15(6): e1002587. https://doi.org/10.1371/journal.pmed.1002587
11. Halpern, B., Mancini, M. C., Bueno, C., Barcelos, I. P., Edna de Melo, M., Lima, M. S., Cipolla-Neto, J. (2019). Melatonin Increases Brown Adipose Tissue Volume and Activity in Melatonin Deficient Patients: a Proof-of-Concept Study. Diabetes, db180956. https://doi.org/10.2337/db18-0956
12. Wolden-Hanson T, Mitton DR, et al. Daily melatonin administration to middle-aged male rats suppresses body weight, intra abdominal adiposity, and plasma leptin and insulin independent of food intake and total body fat. Endocrinology 2000; 141, 487-497.
13. Tan DX, Manchester LC, et al. Significance and application of melatonin in the regulation of brown adipose tissue metabolism: relation to human obesity. Obes Rev 2011; 12, 167-188.
14. Fernandez Vazquez, G., Reiter, R. J., & Agil, A. (2018). Melatonin increases brown adipose tissue mass and function in Zucker diabetic fatty rats: implications for obesity control. Journal of Pineal Research, 64(4), e12472. https://doi.org/10.1111/jpi.12472
15. Amstrup AK, Sikjaer T, Pedersen SB, Heickendorff L, Mosekilde L, Rejnmark L. Reduced fat mass and increased lean mass in response to 1 year of melatonin treatment in postmenopausal women: A randomized placebo-controlled trial. Clin Endocrinol (Oxf). 2016 Mar;84(3):342-7. doi: 10.1111/cen.12942. Epub 2015 Oct 8. PMID: 26352863.
16. Zhang Z, Xue P, Bendlin BB, Zetterberg H, De Felice F, Tan X, Benedict C. Melatonin: A potential nighttime guardian against Alzheimer's. Mol Psychiatry. 2025 Jan;30(1):237-250. doi: 10.1038/s41380-024-02691-6. Epub 2024 Aug 11. PMID: 39128995; PMCID: PMC11649572.
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18. Menczel Schrire Z, Phillips CL, Chapman JL, Duffy SL, Wong G, D'Rozario AL, Comas M, Raisin I, Saini B, Gordon CJ, McKinnon AC, Naismith SL, Marshall NS, Grunstein RR, Hoyos CM. Safety of higher doses of melatonin in adults: A systematic review and meta-analysis. J Pineal Res. 2022 Mar;72(2):e12782. doi: 10.1111/jpi.12782. Epub 2021 Dec 30. PMID: 34923676
19. Tuft C, Matar E, Menczel Schrire Z, Grunstein RR, Yee BJ, Hoyos CM. Current Insights into the Risks of Using Melatonin as a Treatment for Sleep Disorders in Older Adults. Clin Interv Aging. 2023 Jan 12;18:49-59. doi: 10.2147/CIA.S361519. PMID: 36660543; PMCID: PMC9842516.