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...