Melatonin, a hormone that regulates our body’s circadian rhythms, is synthesized at night by the pineal gland. ... It is an ancient molecule, at least 2.5 billion years old, ...

Most melatonin gummies sold in the US contain far more melatonin – a hormone produced naturally by the body that helps regulate circadian rhythms – than what is listed on labels.

Melatonin has been called the hormone of darkness. Naturally secreted by the pineal gland, it is also widely available without a prescription in the United States. What do we know?