The Surprising Truth About Melatonin, America’s Most Popular Sleep Aid

The Surprising Truth About Melatonin, America’s Most Popular Sleep Aid

Melatonin, sometimes called “the hormone of darkness,” is a naturally-occurring molecule produced by the brain's pineal gland which signals to our body that it’s time for sleep. It is also the most popular supplemental sleep aid on the market.  

As the quality of our collective sleep has declined in recent years [1], melatonin sales have skyrocketed. From 2003 to 2014, sales in the U.S rose over 500%, from $62 million to $378 million.  

Recent evidence, however, suggests that melatonin isn’t all it’s cracked up to be. The research on its effectiveness is underwhelming, it may come with harmful side-effects, and it very often has questionable purity.  

Examining the Research on Sleep Quality

A meta-analysis which pooled the results of 17 studies found that when compared to a placebo, melatonin supplementation only increased the speed with which people fell asleep by 3.9 minutes, and improved their sleep quality by a modest 2.2%. [2].  

For a supplement often marketed as a miracle-cure, these results are quite lacklustre. 

They make sense, however, given that melatonin’s role in the brain is simply to signal that it’s night-time, rather than to produce or sustain quality sleep cycles throughout the night.   

Melatonin Not Recommended by American College of Physicians 

These findings are reflected in clinical practice guidelines put forth by the American College of Physicians [3] and the American Academy of Sleep Medicine [4], who independently conclude that there is insufficient evidence to support the use of melatonin to treat insomnia. 

Potential to Treat Jet-Lag 

Given its mechanism of action – setting the clock for sleep, rather than actually producing it – melatonin could theoretically be useful for people suffering from jet-lag, whose biological clocks are severely off-kilter. Even in this population, where melatonin demonstrates some efficacy, researchers conclude that no strong recommendations can be made [5].   

Reported Side-Effects 

With any drug or supplement, it’s important to weigh the benefits against any potential side-effects. As with most exogenous hormones, variable side-effects associated with melatonin supplementation have been reported in the literature [6]:  

  • Daytime sleepiness 
  • Increase in depressive symptoms 
  • Strong nightmares 
  • Headaches 
  • High or Low Blood Pressure 
  • Impaired Glucose Tolerance 
  • Dizziness 
  • Upset stomach 
  • Irritability 

Significant Purity Concerns 

In 2017, a study published in the Journal of Clinical Sleep Medicine found that the content of most melatonin supplements varied widely from their label claims. True concentrations ranged from 83 percent less than to 478 percent more than the amount listed on the label [7]. 

Alternatives For Better Sleep 

Optimize Your Sleep Hygeine  

Check out this article outlining our top five behavioral practices to engineer optimal sleep. If you check the five boxes listed in the article above, you’ll be well on your way to a good night’s sleep. 

Consider our Restful Sleep Formula  

If you’re looking for a natural supplement with science-backed ingredients shown to blunt stress and improve sleep quality, consider the Signature Series Restful Sleep Formula. See the evidence for the ingredients contained within the supplement here


Video: Dr. Matthew Walker on Why Melatonin Is a Poor Sleep Aid 




[2] Brzezinski, A., Vangel, M. G., Wurtman, R. J., Norrie, G., Zhdanova, I., Ben-Shushan, A., & Ford, I. (2005). Effects of exogenous melatonin on sleep: a meta-analysis. Sleep medicine reviews9(1), 41-50. 

[3] Qaseem A, Kansagara D, Forciea MA, et al. Clinical Guidelines Committee of the American College of Physicians. Management of chronic insomnia disorder in adults: a clinical practice guideline from the American College of Physicians. Annals of Internal Medicine. 2016;165(2):125-133. 

[4] Sateia MJ, Buysse DJ, Krystal AD, et al. Clinical practice guideline for the pharmacologic treatment of chronic insomnia in adults: an American Academy of Sleep Medicine clinical practice guideline. Journal of Clinical Sleep Medicine. 2017;13(2):307-349. 

[5] Costello, R. B., Lentino, C. V., Boyd, C. C., O’Connell, M. L., Crawford, C. C., Sprengel, M. L., & Deuster, P. A. (2014). The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature. Nutrition journal13, 1-17. 

[6] Auger, R. R., Burgess, H. J., Emens, J. S., Deriy, L. V., Thomas, S. M., & Sharkey, K. M. (2015). Clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders: advanced sleep-wake phase disorder (ASWPD), delayed sleep-wake phase disorder (DSWPD), non-24-hour sleep-wake rhythm disorder (N24SWD), and irregular sleep-wake rhythm disorder (ISWRD). An update for 2015: an American Academy of Sleep Medicine clinical practice guideline. Journal of clinical sleep medicine11(10), 1199-1236. 

[7] Erland, L. A., & Saxena, P. K. (2017). Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content. Journal of Clinical Sleep Medicine, 13(2), 275-281.  

About our editorial team

The TWC Editorial team is comprised of various wellness practitioners from physiotherapists, acupuncturists, fitness instructors, herbalists, and MDs.

This article does not constitute medical advice. Please consult a healthcare provider for proper diagnosis and treatment.
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