An Overview of the Potential Effects of Melatonin Supplementation on Athletic Performance

Melatonin is a pineal gland hormone. Melatonin is often used to treat insomnia and enhance sleep quality in a range of situations, including jet lag. However, the benefit and safety profile of daytime melatonin dosing prior to exercise are unknown and warrant additional exploration.

We aimed to give (i) a brief overview of the beneficial effects of exogenous melatonin administration on sports performance and (ii) some recommendations for acute use of melatonin with a special focus on humans’ physical activity and athletic performance.

To ascertain the effect of exogenous melatonin administration on humans, a systematic review of the literature was undertaken using PubMed, ScienceDirect, Medline, Google Scholar, and Scopus. Numerous studies in animals have demonstrated the positive impact of melatonin treatment during physical exercise. However, uncertainty remains regarding melatonin's effect on human exercise physiology. Therefore, the present review focuses almost entirely on data obtained from humans.

The gathered data indicate that consuming melatonin at night improves sleep quality. In terms of physical activity and sports performance, past research has demonstrated that melatonin administration has a good effect on decreasing oxidative stress and inflammation induced by exercise and providing additional protection for skeletal muscle against exercise-induced oxidative damage in humans. However, when taken at bedtime, melatonin may have an unfavourable influence on performance during acute and strenuous exercise.

Exogenous melatonin administration prior to exercise shows significant chronobiotic, antioxidant, antiadrenergic, and hypothermic effects and may represent a fascinating potential weight loss method. However, consuming a high amount of melatonin (6 mg) 50 minutes prior to commencing exercise is not recommended because it may interfere with the physiological reactions to physical activity. Melatonin-related adverse effects were mainly transient and were associated with daytime doses. Melatonin should therefore be provided at night whenever possible.