Different brain regions regulate the circadian clock and process light input for mood regulation.

“So the SCN that I told you about earlier, the place where the central pacemaker is, the one that receives direct input from the retina through the IPRGCS to adjust your circadian clock is not the area that receives the light input for mood regulation. It's a completely different brain region. And what's really amazing, this region also receives direct input from the IPRGC's but projects to areas in the brain that are known to regulate mood including the vententral medial prefrontal preffrontal cortex which has been studied for many years to be impacted in a human depression.”