Part 6/16:
A significant portion of the transcript explores the body’s circadian system. The retinal ganglion cells containing special photopigments (notably melanopsin) are directly sensitive to ambient light, especially in the blue spectrum. These cells send signals to the suprachiasmatic nucleus (SCN) in the hypothalamus, the brain’s master circadian clock. The SCN orchestrates rhythms across nearly all tissues, coordinating processes like hormone secretion (e.g., melatonin), body temperature, and alertness.