Melatonin is produced in tissues other than the Pineal gland
Melatonin is the major hormone product of the pineal gland. However, this does not make the pineal gland the only place in the body melatonin is produced. But many Professional and Social Media Influencers are unaware of the other organs in the body that produce Melatonin in much greater amounts.
Melatonin production increases in the pineal gland during the dark phase (night and from Fall Equinox to Winter Solstice). Its secretion from the pineal gland has been classically associated with circadian and circanual rhythm regulation and thus sleep.
However, melatonin production is not confined exclusively to the pineal gland, but other tissues including retina, tear glands, gut (400X more than Pineal Gland), ovary (200X more than the Gut), testes, bone marrow, thymus and bone marrow of humans and lens also produce it.
The gastrointestinal (GI) tract presents another, many times larger, source of melatonin. Melatonin acts on the immune system by regulating cytokine production of immunocompetent cells. It also possesses the ability to modulate immune responses by regulation of the T helper 1/2/17 balance and cytokine production.