Why is "good morning and "good afternoon" a greeting and "good night" a way of saying good bye?

Question

It's the same everywhere that "good night" is a way of saying bye. Why is that?

Answer 1

According to the the Oxford English Dictionary (OED), good-bye is a contraction of the phrase, "God be with you." Additionally, the OED defines good night as a customary phrase used at parting at night or going to sleep, and describes it as a contraction of the phrases, "Have good night" or "God give you good night." (FYI: while many people spell good-bye as goodbye and good night as goodnight, the OED does not recognize those spellings.)

May you sleep comfortably this evening!

Answer 2

In addition to "good morning" and "good afternoon", there is also the choice of "good evening".

Have a "good night" does usually men that you won't be seeing that person until at least the next day.

Answer 3

Wow i never thought about that...
Maybe because night is the time people should rest and not do anything

Answer 4

Very simple. Night is the end of day.

Answer 5

Things that make you go "hmmmmm..." lol