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?
I’m pretty sure that’s the general hypothesis in the field, but as you might imagine, it’ll be very difficult to prove. There was a study done sometime (I don’t fully remember when) where researchers collected data on when people go to sleep and when they wake up, and they found that there was a remarkably normal distribution in the population for when people wake up and sleep.
My personal interpretation is that chronotypes (what you call early birds and night owls) are genetic in some way, but I don’t specialize in this area, so don’t take my word for it