good things only on good days

so on a chanel named O1G i saw that two horses spawned during the night because of a torch... [dramatic funny music] so i thought why should good mobs spawn during the night because of the light level so i thought of that good mobs won't... EVER SPAWN IN THE NIGHT same goes for already spawn good mobs they very slowly start to despawn showing that they are sleeping [i don't understand why should the mobs despawn] thats it thank you for reading...