Here is my guess:
Most action in the animal kingdom, above and under water, takes place at sunrise and sunset. Animals seek out prey and seek out protecting from predators during those times. In Africa for example, most of the action is over by 8 AM; it does not start until around sunset. It's the same on the coral reef. This has been true for millions of years. Perhaps the reason we like sunrises and sunsets is because millions of years ago, it was at those times when we were most alert to danger and exhilarated by a potential meal – and perhaps somewhere buried in our minds are those feelings.
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And here is what Dr. Richard Zakia, author of Perception of Imaging, says about sunrises:
I think you hit the nail on the head with your insight. We are part of the animal world. I think if we did not live in our civilized world we might be more attentive to sunrise and sunset, like our farmers are. I wonder if animals were 'civilized', like those that live in a zoo or aquarium, respond the same way to sunset and sunrise as those in the wild.
I recall an experiment that was done some years back where a woman was put in a
dark space for a couple of days to determine whether she could tell sunrise from sunset,
sleep time from wake time, or something like that. The result was astonishing. She could.