Melatonin & Caffeine Timing Boosts Performance, Cuts Damage

A recent randomized controlled trial suggests that taking melatonin before bed and caffeine the next morning may improve high‑intensity running performance while lowering markers of muscle damage and inflammation.

For athletes and fitness enthusiasts, the combination of caffeine and melatonin has traditionally been viewed as a contradiction – one promotes wakefulness, the other sleep. But a new study published in Nutrients (DOI: 10.3390/nu18091425) challenges that simple opposition. Researchers from Tunisia, Spain, and Norway found that when taken in a specific chronological sequence – melatonin at night, caffeine the following morning – the two compounds may work together to enhance exercise performance and accelerate recovery.

Why melatonin and caffeine are not just opposites

Melatonin is best known as a chronobiotic – a substance that regulates the body's circadian rhythm. It also possesses strong antioxidant activity, reducing inflammation and oxidative damage, particularly protecting mitochondria. This makes it a promising agent for post‑exercise recovery.

Caffeine is a well‑established central nervous system stimulant and ergogenic aid. It fights fatigue by blocking adenosine receptors. However, caffeine consumed late in the day can disrupt sleep, which in turn impairs recovery and subsequent performance.

Because their primary effects seem opposite, researchers wanted to explore whether timing could turn them into a complementary pair rather than competitors.

What the study did

The trial was a randomized, double‑blind, placebo‑controlled crossover study involving 14 trained male athletes. All participants abstained from caffeine for 48 hours before each trial session. Each participant underwent four experimental conditions, with a 7‑day washout period between each:

• PLA + PLA – placebo at night + placebo in the morning
• PLA + CAF – placebo at night + caffeine (3 mg/kg) in the morning
• MEL + PLA – melatonin (6 mg) at night + placebo in the morning
• MEL + CAF – melatonin (6 mg) at night + caffeine (3 mg/kg) in the morning

One hour after the morning supplement, participants completed a 5‑meter shuttle run test (5mSRT): six 30‑second maximal intensity sprints with 35 seconds of passive recovery between sets. Researchers measured total running distance, peak and average heart rate, rating of perceived exertion (RPE), and blood biomarkers of muscle damage (e.g., creatine kinase) and inflammation.

Key findings: performance, recovery & heart rate

1. Performance improved with both caffeine alone and the melatonin+caffeine combination

Compared to the double‑placebo group, all supplement conditions (PLA+CAF, MEL+PLA, MEL+CAF) increased total shuttle run distance. Notably, the MEL+CAF combination produced performance gains that were at least as good as caffeine alone – without any negative interaction.

2. Melatonin+caffeine significantly reduced muscle damage and inflammation

Blood markers showed that the MEL+CAF group had lower levels of muscle damage and inflammatory markers compared to both the caffeine‑only group and the placebo group. This suggests that night‑time melatonin may prime the body to tolerate high‑intensity exercise better the next morning.

3. Lower heart rate response in the combination group

The melatonin + caffeine group exhibited a lower peak heart rate response during the shuttle run test. The researchers speculate this may be due to melatonin's modulation of autonomic nervous balance, potentially making high‑intensity efforts less physiologically stressful.

4. No significant effects on sleep parameters

Interestingly, neither melatonin nor caffeine (taken in the morning, after a night of melatonin) significantly altered sleep measures in this study. This suggests that morning caffeine does not necessarily "cancel out" melatonin's effects when the two are separated by a full night.

Practical takeaway

The study indicates that separating melatonin and caffeine by a full night's sleep may allow both to contribute positively to exercise performance and recovery. For those considering this approach, the protocol used in the study was:

• 6 mg of melatonin taken before bedtime on the night before a high‑intensity training session
• 3 mg/kg of caffeine taken the next morning, approximately one hour before exercise

Again, these are research parameters, not personal recommendations. Always speak with a qualified healthcare provider before starting any new supplement regimen.

Limitations

The researchers caution that this was a small‑scale study (14 participants) and results should be interpreted with caution. Future studies are needed to confirm the findings in larger and more diverse populations (including female athletes), and to test different dosages. Individual responses may vary based on caffeine tolerance, melatonin sensitivity, and chronotype.

Reference

Mahdi, N. et al. (2026). Melatonin, Caffeine, or Their Combination: Effects on Sleep, Performance, Perceived Exertion in a Placebo‑Controlled Crossover Study. Nutrients, 18(9), 1425. https://doi.org/10.3390/nu18091425