Basic Pineal Body Function. The pineal gland is one of the most important endocrine glands. Further, it regulates other glands as well, such as pituitary and thyroid. The essential function of the pineal gland is to secrete melatonin. And that, in turn, impacts the central nervous systems greatly.
Unlike most of the mammalian brain, the pineal gland is not isolated from the body by the blood–brain barrier system; it has profuse blood flow, second only to the kidney, supplied from the choroidal branches of the posterior cerebral artery.
The pineal gland is a small endocrine gland in the brain of animals with backbones. The pineal gland produces melatonin, a serotonin-derived hormone which modulates sleep patterns in both circadian and seasonal cycles. The shape of the gland resembles a pine cone from which it derived its name.