The pineal gland is a bioclock sensitive to the Sun’s photoperiodic radiation.
This tiny gland, shaped like a pine cone, is a neuroendocrine transducer that converts nervous system transmissions into hormonal messages via the synthesis and secretion of melatonin.
The dawn’s early light is bright enough to act as a time cue that entrains us to Earth’s 24-hour day.
The pineal gland also acts as a “happy gland.”
It contains the harmal alkaloid 6-methoxytetrahydroharmane, which produces euphoria, mental imagery, and sexual desire.
The human pineal gland is attached to the third ventricle of the brain, and is only about the size of a pea..
In contrast, half of all the tissue inside a baby seal’s head is pineal gland.
According to Melatonin: Biosynthesis, Physiological Effects, and Clinical Applications (edited by Hing-Sing Yu & Russel J. Reiter), 1998 …
“Melatonin is also found in human cerebrospinal fluid, its concentration in the spinal fluid of the calf is higher than in the plasma. Furthermore, the melatonin concentration of spinal fluid shows a daily rhythm.”