The 555 is the peek of the cells that provide vision. The circadian sensor is separate from vision, it receives light that comes from top, its range goes beyon

The 555 is the peek of the cells that provide vision. The circadian sensor is separate from vision, it receives light that comes from top, its range goes beyond vision range into ultraviolet, its sensitivity goes up with the light frequency. The recommendation to go for a walk outside in the morning to fix the circadian rythm is basically to get ultraviolet coming from the top to your eyes, as that is most effective. In the evening any required lighting should be dim, red and coming from bottom. Blue light screen filters do help somewhat but the sum of the remaining lower bands still has the potentiall to mess up the circadian. source: Andrew Huberman podcasts on sleep