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# Melatonin

mel·a·to·nin - mel-ah-TOH-nin

## Definition

Melatonin is a [hormone](/glossary/hormone) produced primarily by the pineal gland in the brain that regulates the body's sleep-wake cycle ([circadian rhythm](/glossary/circadian-rhythm)). Often called the 'sleep hormone,' melatonin doesn't directly induce sleep but rather signals to the body that it's time to prepare for sleep by promoting drowsiness, lowering body temperature, and shifting the body into nighttime physiology. Melatonin production is controlled by light exposure - darkness stimulates its release, while light suppresses it.

Melatonin secretion follows a predictable daily pattern: levels begin to rise in the early evening (typically 2-3 hours before your natural bedtime), peak during the middle of the night, and decline toward morning as light exposure increases. This pattern is synchronized primarily by the suprachiasmatic nucleus (SCN) in the brain, which receives light information from the retina. Blue light from screens and artificial lighting is particularly effective at suppressing melatonin production, which is why evening screen use can disrupt sleep onset.

Beyond sleep regulation, melatonin functions as a powerful antioxidant, supports immune function, influences reproductive hormone cycling, and may play roles in [blood pressure](/glossary/blood-pressure) regulation and neuroprotection. Melatonin supplements are among the most popular sleep aids worldwide and are available over-the-counter in many countries, though in some European countries they require a prescription.

## Also Known As

Sleep hormone N-acetyl-5-methoxytryptamine 

## Key Facts

-   • Melatonin production begins to decline in adolescence and continues decreasing with age, potentially contributing to sleep difficulties in older adults. 
-   • Blue light from screens suppresses melatonin production by up to 50% - more than any other light wavelength. 
-   • Supplemental melatonin is most effective for circadian rhythm disorders (jet lag, shift work) and delayed sleep phase disorder. 
-   • Typical supplemental doses (0.5-5 mg) are often much higher than the body's natural production (~0.1-0.3 mg). 
-   • Melatonin is produced not only in the pineal gland but also in the gut, retina, bone marrow, and immune cells. 

## How It Relates To Your Health

Melatonin supplementation is most evidence-supported for jet lag recovery, shift work sleep disorder, and delayed sleep phase disorder (difficulty falling asleep at conventional times). For general insomnia, the evidence is more modest, and melatonin is most effective for improving sleep onset latency (time to fall asleep) rather than total sleep duration.

If you're considering melatonin supplementation, start with the lowest effective dose (0.5-1 mg) taken 1-2 hours before desired bedtime. Melatonin is generally considered safe for short-term use but may interact with blood thinners, diabetes medications, immunosuppressants, and birth control. Prioritizing natural melatonin production through evening light hygiene is the preferred first approach.

## Related Terms

[Circadian Rhythm](/glossary/circadian-rhythm)[Sleep Cycle](/glossary/sleep-cycle)[REM Sleep](/glossary/rem-sleep)[Serotonin](/glossary/serotonin)[Cortisol](/glossary/cortisol)[Hormone](/glossary/hormone)

## Related Articles

[![Sleep Hygiene: 12 Evidence-Based Tips](https://images.unsplash.com/photo-1541781774459-bb2af2f05b55?w=1200&h=630&fit=crop&fm=webp)](/wellness/sleep-hygiene-evidence-based-tips)

[](/wellness/sleep-hygiene-evidence-based-tips)[Wellness](/wellness)

### Sleep Hygiene: 12 Evidence-Based Tips

2025-09-15

[![How to Build a Morning Routine That Actually Sticks](https://images.unsplash.com/photo-1506126613408-eca07ce68773?w=1200&h=630&fit=crop&fm=webp)](/wellness/morning-routine-that-sticks)

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### How to Build a Morning Routine That Actually Sticks

2026-01-08

## Sources

1.  [Melatonin: What You Need To Know](https://www.nccih.nih.gov/health/melatonin-what-you-need-to-know) - National Center for Complementary and Integrative Health (NIH)
2.  [Melatonin](https://www.mayoclinic.org/drugs-supplements-melatonin/art-20363071) - Mayo Clinic
3.  [Physiology, Melatonin](https://www.ncbi.nlm.nih.gov/books/NBK550972/) - StatPearls / PubMed

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