Full Pineal Gland Description
[Continued from above] . . . gland grows into an eyelike structure; in others, although it isn't a fully developed eye, it is still able to act as a light receptor. Because of this, the pineal gland is also known as the third eye.
Along with secreting melatonin, the pineal gland also regulates other endocrine functions and converts signals from the nervous system into endocrine signals. Melatonin production (or the lack of it) can contribute to a person feeling awake or becoming sleepy, and the pineal gland's endocrine function regulation can also influence sexual development.