The pineal gland (also known as the pineal body, epiphysis-cerebri, pineal organ or conarium) is a small endocrine gland found in vertebrates that converts serotonin and synthesizes it into melatonin (more about melatonin here), a hormone derived from tryptophan, which regulates the roughly 24-hour cycle of biological activities associated with periods of light and dark, otherwise known as the circadian rhythm.
The pineal gland develops during the 2nd month of gestation. It is one of the smallest glands of the endocrine system and is responsible for our sleep/wake system as well as our sexual development cycles.
The shape of the pineal gland closely resembles that of the pine-cone from which it derived its name. The size of the pineal gland in adult humans is normally between 5mm-8mm (~0.2-0.3 inches) long, about the size of a grain of rice, and weighs approximately 0.1 grams. Continue reading “Pineal Gland Anatomy”