The spoken usage of "night" as an informal, acquainted version of "good night" (wishing one particular a restful sleep) is widespread, but I am not sure what the right penned equivalent is - when there is a single. I've always employed 'Night having an apostrophe, generally capitalized: eight ᴀ�???12 ᴘᴍ?? https://juliusy9k20.onesmablog.com/the-best-side-of-night-gangnam-퍼펙트가라오케-karaoke-guide-78836904