Mechanism

Endogenous melatonin

Hormone produced by the pineal gland in response to darkness. Its circadian rhythm marks the 'biological night': it rises at dusk, peaks between 2 and 4 am, and falls on waking. It regulates sleep and the circadian rhythm, and has antioxidant and immune-modulating effects.

Effect by goal · level of evidence

Sleep and circadian rhythm

regulates Very high physiology (A)

Circadian basis

Marks the biological time to sleep. It is synthesized from serotonin. Blue light after dark suppresses its production by up to 50%.

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Decline with age

reduces Very high physiology (A)

Insomnia in older adults

Production falls progressively from age 40, with a marked loss of amplitude of the nighttime peak. It is one of the bases of insomnia in older adults.

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Endogenous antioxidant

protects Moderate physiology (A)

Potent antioxidant

One of the most potent endogenous antioxidants known. It scavenges free radicals directly and stimulates antioxidant enzymes.

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Immune modulator

modulates Moderate preclinical + observational (A)

Immune pathway

Modulates innate and adaptive immunity. Its decline with age has been linked to immunosenescence. Target under investigation in oncology (adjuvant).

Information, not medical advice. Scientific evidence reflects the quality of the studies.