We already have "before sunrise" and "middle of the night" and "after dark" and sunrise and sunset and so on. Most of the time, there's little or no gain from attaching a number instead of using one of those.
(I'm not arguing in favor of switching, just pointing out that we already have the descriptions for times of day)
(I'm not arguing in favor of switching, just pointing out that we already have the descriptions for times of day)