Is it because evolution dictates that night is too difficult to operate in when all creatures have access to daylight which allows clear awareness of the environment around any organism? It almost seems like the evolution of multiple different organisms has come to a truce or mutual agreement that all organisms will sleep during the same time (besides a few nocturnal creatures which don't seem to have significant enough advantage to crowd out and outcompete other organisms). If not sleeping at all had a significant advantage, wouldn't we see most if not all creatures doing it? Sleep must allow for certain biological processes to be completed more quickly and efficiently which, if an organism evolved to not sleep at all would be so slow that it would cause serious detriment to fitness. But if all organisms had the same detriment to fitness why would it matter? Maybe the answer lies in the fact that an ambush on another organism while sleeping is not of enough value, on average, to be worth pursuing? It's possible that an ambush on another sleeping organism ends in the attacker's death more often than not, making it a maladaptive tactic, leading to most organisms sleeping at night rather than seeking out other organisms to eat in a dimly lit or almost completely unlit environment.

Otherwise, it must be a necessary connection to the astral plane which all highly evolved creatures must access or telecommunicate with using big brain antennas in order to be as highly fit as they are