I know evolution is governed by chance and it is random but does it make sense to “ruin” sleep if there’s light? I mean normally, outside, you never have pure darkness, there are the moon and stars even at night. In certain zones of the Earth we also have long periods of no sunshine and long periods of only sunshine.
I don’t know if my question is clear enough but I hope so.
Bonus question: are animals subject to the same contribution of light or lack of it to the quality of sleep?
Oh trust me, I know way more than you think. It is literally my job to study circadian rhythms. I can very comfortably say that you’re wrong
https://en.m.wikipedia.org/wiki/Light_effects_on_circadian_rhythm
For anyone else, I won’t try to change your mind.
Yes, but your wikipedia link doesn’t prove that animals are only sensitive to blue light, only that they are more sensitive to blue light. That is a very well-documented phenomenon. But there is plenty of evidence that red light can entrain circadian rhythms as well, dating well back to the 80’s. There has even been a study that identified different mechanisms of entrainment to low-wavelength and high-wavelength light in bacteria, which you can find below. My point is that it is very scientifically irresponsible, and in fact, blatantly wrong, to claim that humans are sensitive only to particular wavelengths of light, when in fact humans and other animals are sensitive to all wavelengths of visible light.
Beyond that, I don’t necessarily know why you seem to be claiming that the intensity of the ambient light does not matter for photic entrainment, when this is a highly documented and, in fact, highly studied phenomenon in the circadian field. Yes, the moon reflects light, but this is dim enough that mammalian SCN’s can interpret the difference between that and the full daylight. See below for some papers that look into light intensity and their effects on entrainment.
Here is some reading if you are interested: