Melatonin is well-known as the hormone that governs the sleep-wake cycle. It has received significant attention for its broad physiological effects. Although its sleep-promoting and circadian regulating roles are prominent and appreciated [1,2], emerging evidence suggests that its effects extend to boosting endurance capacity, improving recovery, and augmenting athletic performance. We've also previously discussed melatonin's role in diabetes and weight loss, its anticancer potential, and its role in easing depression and anxiety.
This article seeks to examine the multifaceted ways in which melatonin may support endurance athletes and recreational exercisers alike, delving into mechanistic insights, safety profile, and practical considerations for supplementation.
Melatonin Beyond the Realm of Sleep
Melatonin is found throughout nature and is produced by many living organisms. In humans, the pineal gland is the major site for melatonin production, but the retina, white blood cells, bone marrow, gastrointestinal tract, and thymus can all produce it.
The synthesis and secretion of melatonin are suppressed by light and enhanced in the dark. It exerts its effects through different pathways, with the predominant type of receptors expressed by mammalian organs being melatonin receptor 1 and 2 (MT1/2).
As described above, melatonin helps regulate sleep patterns and circadian rhythms, and these are perhaps its most well-known functions. In addition, melatonin acts as an antioxidant and plays a role in energy metabolism, immune regulation, reproduction, puberty timing, and mood disorders. It also helps suppress pro-inflammatory cytokines and improves the efficiency of mitochondria in cells, which produce the energy required for life, including exercise [3,4].
Deficiencies in melatonin production or synthesis have been linked with the onset of many disorders, like breast cancer, as well as neurodegenerative conditions [4].
The systemic effects of melatonin form the basis for investigating its potential to enhance exercise endurance and recovery.
Melatonin in Exercise and Sport Performance
Endurance performance depends on efficient energy metabolism, oxygen delivery, and high resistance to fatigue [5,6].
Mitochondrial density and function are crucial aspects of aerobic endurance. Animal studies indicate that melatonin supplementation increases markers of mitochondrial biogenesis (such as PGC-1α) alongside exercise, improves exercise tolerance, and increases the replenishment of muscle glycogen (a vitally important fuel for endurance exercise training) [7].
Some evidence suggests melatonin may upregulate hypoxia-inducible factors (HIFs) [8], aiding cellular adaptation to lower oxygen availability [9] and potentially boosting endurance at high altitudes or during intense aerobic efforts.
By mitigating exercise-induced oxidative stress [10,11], melatonin could preserve the contractile function of muscle and delay the onset of fatigue, allowing athletes to sustain higher work rates for longer.
Melatonin and Recovery
Recovery involves muscle repair, the resolution of inflammation, and the restoration of energy stores. Melatonin can potentially support this by downregulating pro-inflammatory cytokines and promoting the elevation of anti-inflammatory cytokines [11], which might accelerate tissue repair.
Through its effects on sleep quality, melatonin may help enhance growth hormone secretion during the night [12], indirectly boosting muscle protein synthesis and recovery [13,14].
Impaired sleep often results in prolonged recovery times and blunted performance, with the effect worsening the longer the exercise activity is [15-17]. This is obviously less than desirable for endurance-type activities. Extended sleep, as opposed to normal or partial sleep, leads to better maintenance of endurance performance [18], and melatonin may assist with this.
Improved sleep not only primes the neuromuscular system to adapt to training but also supports mental resilience and fatigue avoidance during competition.
Dosage Considerations and Timing in Melatonin Supplementation
Optimal dosing strategies for athletic applications are not yet standardized in the evidence base. In fact, doses as low as 2.5 mg all the way up to 100 mg have been reported across various population groups, including athletes [19].
A recent meta-analysis (a study of the available evidence) has suggested that advancing the timing of melatonin provision to 3 hours before desired bedtime, at a dose of 4 mg/day, might be preferable for sleep promotion over the schedule most often used in clinical practice (2 mg taken 30 minutes before the desired bedtime) [20].
Safety Profile and Potential Side Effects
Melatonin is generally well-tolerated and has a favorable safety profile, even at doses up to 10 mg/day [21]. Reported side effects are mild, transient, and have a lot of individual variability. Nevertheless, these can include drowsiness, vivid dreams or nightmares, and headaches/dizziness [22].
Long-term safety data remain limited, but no serious adverse events have been consistently linked to melatonin. Athletes should ensure melatonin supplements are sourced from reputable manufacturers to avoid variability in potency and purity.
Conclusion
Melatonin’s role extends well beyond sleep regulation, encompassing antioxidant, anti-inflammatory, and mitochondrial-protective actions that are highly relevant to endurance exercise and recovery. While human research in athletic populations is still emerging, existing mechanistic and preliminary performance data point to melatonin as a promising supplement for endurance athletes seeking enhanced recovery and resilience.
Careful dosing, consistent timing, and ongoing monitoring are key to unlocking melatonin’s full potential within a comprehensive athletic performance strategy. Future large-scale clinical trials will further clarify optimal protocols and long-term implications, but for now, melatonin represents a safe, accessible tool in the athlete’s recovery arsenal.
If you are having challenges with sleep induction and maintenance, melatonin may be something to consider to help, especially with travel and as we age. However, if you are interested in a more comprehensive sleep solution, check out Tro Zzz, our buccal troche formulated for sleep that has melatonin as one of its main ingredients + 7 more to help you fall asleep, stay asleep, and wake up feeling refreshed.
If you're a practitioner, check out Tro+ Somna (which can come with or without melatonin). It's designed to tackle even the most challenging sleep disturbances. If your patients really struggle to fall asleep or stay asleep, before reaching for the prescription (or calling in a refill), Tro+ Somna may be their answer!
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