The surprising supplement to take before your workout to torch more carbs and boost performance

A common sleep supplement taken by roughly six million adults may do more than help someone rest; emerging research suggests it could also give their morning workout an edge.

Multiple studies now indicate that melatonin, a natural hormone best known for regulating the sleep-wake cycle, may help athletes and active individuals burn more carbohydrates, reduce muscle damage and recover faster from intense exercise.

One of the latest trials found that combining six milligrams of melatonin at night with a morning dose of caffeine improved high-intensity workout performance one hour later, while also reducing markers of muscle damage and inflammation compared to a placebo.

Athletes on the melatonin-caffeine combo covered more ground, sprinted farther, and had lower heart rates than those on placebos, indicating that their hearts were doing more work with less strain. 

Beyond performance, the combination reduced several markers of muscle damage and inflammation after exercise. Past research has also shown that melatonin can boost carbohydrate metabolism and help reverse exercise-induced muscle damage.

Researchers say the findings suggest a positive relationship in which melatonin helps the body recover overnight, while caffeine provides a morning boost, together allowing athletes to perform better and burn more calories with less physiological strain.

Opposite melatonin, caffeine is a stimulant that blocks adenosine, the brain chemical that causes fatigue. This reduces perceived effort, increases alertness and enhances muscle contraction, boosting endurance and power when taken about an hour before exercise.

The new findings add to a growing body of evidence that together paints a clearer picture of how melatonin might benefit active individuals.

‘Optimizing both recovery-related processes during sleep and arousal-related mechanisms before exercise may provide a more effective strategy to enhance performance than targeting either pathway in isolation,’ the authors wrote.

In the new trial, researchers in Tunisia recruited 14 trained male athletes.

Each one spent four separate nights in a sleep lab about one week apart.   

Researchers tested four different conditions in random order, including a placebo supplement before bed and another in the morning, a placebo at night followed by 3 mg of caffeine per kilogram of body weight (about 200 mg for an average man) in the morning, 6 mg of melatonin at night followed by a morning placebo, or both supplements together.

One hour after the morning dose, the athletes completed a high-intensity five-minute shuttle run test, which involved six 30-second sprints with 35 seconds of rest between each.

Researchers measured sleep quality overnight using a device on participants’ wrists that contained an accelerometer to measure physical movement and collected blood samples before and after exercise to assess markers of muscle damage and inflammation.

The combination of melatonin and caffeine produced the most notable benefits.

Compared with the placebo group, athletes who took both melatonin at night and caffeine the next morning covered a significantly greater total distance during the high-intensity shuttle run test, meaning they sustained more work over the six 30-second sprints.

Specifically, total distance increased by roughly five to seven percent compared to the placebo-only condition, a modest but meaningful improvement for competitive athletes looking to maximize their training.

They also showed lower levels of several muscle damage markers, including creatine kinase, lactate dehydrogenase and C-reactive protein, suggesting reduced inflammation and greater potential for faster recovery.

The latest research builds on past studies that have found additional benefits of adding melatonin to workout preparations.

A small study published in the International Journal of Exercise Science in 2017 found that taking 6 mg of melatonin half an hour before aerobic exercise led the body to burn more carbohydrates for fuel rather than fat.

Researchers tested 24 healthy, active young adults who walked on a treadmill for 30 minutes on four separate occasions — twice after taking melatonin and twice after taking a placebo.

The results showed that after melatonin, participants switched to burning mostly carbohydrates at a lower exercise intensity than with the placebo. Overall, they burned significantly more carbs and a smaller percentage of fat during the same workout.

Burning more carbohydrates during exercise can be beneficial because carbs are a more efficient fuel source than fat, especially at higher exercise intensities.

For an athlete looking to sustain energy or improve performance, shifting toward greater carbohydrate intake might help, though the study did not measure actual performance outcomes such as speed or endurance.

A systematic review published in Nutrients analyzed 21 clinical trials involving 354 highly trained athletes and found that melatonin supplementation offers several health benefits for athletes, though whether it directly improves sports performance is still uncertain.

Melatonin demonstrated clear benefits for athlete health. Taking it about an hour before bed improved antioxidant status, reduced inflammation and helped reverse liver and muscle damage caused by intense exercise.

It also had moderate positive effects on blood sugar, total cholesterol, triglycerides, and kidney function markers. No adverse effects were reported.

Doses ranged from 5 mg to 100 mg, with 5 mg, 6 mg and 10 mg being the most common. Supplementation was given either before or after exercise, for as little as one day or up to 30 days.

The true effectiveness of melatonin for directly improving sports performance, such as strength, power, speed or endurance, remains unclear. While some studies showed benefits in aerobic capacity, anaerobic power, balance and reaction time, results were inconsistent across trials.

The authors noted that melatonin's antioxidant and anti-inflammatory properties may indirectly help performance by speeding recovery and reducing tissue damage, rather than providing an immediate boost during exercise.

A separate review published in February found that taking melatonin in the evening at least 6 hours before exercise produced the best results, with moderate-to-large benefits for endurance performance and significant reductions in muscle damage markers such as creatine kinase.

Taking melatonin for several nights in a row during intense training blocks yielded substantially larger effects than a single dose.