Can melatonin help improve athletic performance?

According to a systematic review, published in the journal Nutrients, melatonin’s antioxidant and anti-inflammatory properties may counteract the effects induced by high-intensity physical exercise performed by high-level athletes.

The study authors concluded: “Melatonin supplementation could act indirectly to improve performance by preventing tissue damage and helping to reduce inflammation caused by RONS [reactive oxygen and nitrogen species], restoring circulating biomarkers that go out of the normal range in highly trained athletes when performing very demanding exercises.”

Melatonin: A neurohormone with antioxidant, anti-inflammatory, and immunoregulatory properties

Melatonin, a neurohormone known for its role in regulating circadian rhythms, has received attention chiefly within the field of sleep health. It is known to modulate a variety of physiological functions thanks to its antioxidant, anti-inflammatory, and immunoregulatory properties.

The study authors, from various research institutions across Spain, set out to critically review the effects of melatonin supplementation in sports performance and circulating biomarkers related to the health status of highly trained athletes.

Data was obtained from the Web of Science, PubMed, and Scopus during a search carried out in February 2024 from original articles published with a controlled trial design. Of 294 references, 21 articles were selected, according to the inclusion and exclusion criteria. The dose of melatonin supplemented in trials ranged between 5 and 100 mg, administered before or after exercise.

The results found that melatonin has a high safety profile. Outcomes showed improvements in antioxidant status and inflammatory response, as well as reversed liver damage and muscle damage. Moderate effects on modulating glycemia, total cholesterol, triglycerides, and creatinine were also reported.

There were also promising findings on the potential benefits of melatonin in haematological biomarkers, hormonal responses, and sports performance.

Melatonin’s efficiency to directly improve sports performance ‘remains to be assessed’

The researchers attributed the improvements in certain health biomarkers to melatonin’s activity in counteracting some of the effects induced by high-intensity exercise, such as oxidative stress, inflammation, and skeletal muscle-induced damage.

However, they also identified a research need to consider diet analysis in athletes, as none of the studies included determined plasma levels of endogenous melatonin.

“Certain foods can significantly increase the concentration of melatonin, such as barley, rice, and tomatoes (in vegetables and cereals), cherries, strawberries, and grapes (in fruits), chicken or beef, olive oil, and nuts,” the authors wrote. “Other compounds, such as caffeine, vitamins, and/or minerals, would modify the synthesis of melatonin.”

Ultimately, they admitted, the molecular and physiological mechanisms of melatonin to directly improve sports performance remain to be determined.

“The true efficiency of melatonin to directly improve sports performance remains to be assessed,” they concluded. “Nevertheless, an indirect effect of melatonin supplementation in sports performance could be evaluated through improvements in health biomarkers.”