[bXVsbGVy]

There are plenty of evidence that the activation of ipRGC inhibits melatonin production.

My question was about the "ratio of yellow photons to blue photons".

Fun fact: Blue light can stimulates melanogenesis in dark-skinned individual (type III and above) [1], no UV required. This process is mediated by an Opsin, like our vision.

This is a somewhat recent discovery (~2010) and the physiological effects are still largely unknown. Most studies on the subject are concerned about hyperpigmentation and oxidative stress.

[1] https://www.sciencedirect.com/science/article/pii/S0022202X1...

[hollerith]

The "ratio of yellow photons to blue photons" is a verbatim quote from the podcast episode. Huberman didn't expand on that in the episode, and (again) my search for specifics yielded no additional understanding.

But Huberman was quite clear that the spectrum of light when the sun is low in the sky is different somehow from the spectrum when it is high, and the eye has some way to detect this difference.

The important fact is that when the sun is high in the sky, the light has very little effect on the timing of a person's circadian rhythm, and Huberman was quite clear on that too.

Most people do not seem to know that yet!