What Melatonin Is
A hormone produced mainly by the pineal gland in response to darkness.
Regulates circadian rhythm (sleep–wake cycle).
Also functions as an antioxidant and immune modulator.
Available as an over-the-counter supplement in many countries.
 
Sleep and Circadian Rhythm
Insomnia: Improves sleep onset, especially in people with delayed sleep phase syndrome or jet lag.
Shift work: Helps night-shift workers adapt to altered sleep schedules.
Children: May be used in children with autism, ADHD, or other neurodevelopmental conditions where insomnia is common.
Older adults: Natural melatonin production declines with age; supplementation may improve sleep efficiency.
 
Antioxidant and Anti-Inflammatory Effects
Neutralizes free radicals and enhances activity of antioxidant enzymes.
Protects mitochondrial function under stress.
Reduces oxidative damage in tissues including the brain, heart, and liver.
 
Immune Function
Modulates immune responses, balancing pro- and anti-inflammatory cytokines.
Studied for potential supportive role in viral infections and sepsis.
 
Neurological and Cognitive Benefits
Neuroprotective in animal and preclinical studies.
May reduce risk of neurodegenerative conditions (Alzheimer’s, Parkinson’s) by reducing oxidative stress and abnormal protein aggregation.
Early human studies show possible improvements in cognition and delirium prevention in older patients.
 
Cancer Research
Laboratory and animal studies suggest melatonin can inhibit tumor growth, promote apoptosis in cancer cells, and reduce metastasis.
May enhance the effects of chemotherapy and reduce treatment side effects (e.g., fatigue, immune suppression).
Clinical trials in humans are limited; not an approved cancer treatment.
 
Other Potential Benefits
Cardiovascular health: May lower blood pressure modestly, especially at night, and improve lipid profile.
Metabolic effects: Some studies suggest improved insulin sensitivity and weight regulation.
Eye health: Protective against oxidative stress in retina; may support macular health.
Headaches: Used in prevention of cluster headaches and migraines.