The spoken use of "night" as a casual, common Edition of "fantastic night" (wishing a single a restful slumber) is frequent, but I am not sure what the right written equivalent is - if there is just one. I have normally employed 'Night having an apostrophe, normally capitalized: One example https://claytong3t64.webbuzzfeed.com/38297999/the-best-side-of-night-gangnam-퍼펙트가라오케-karaoke-guide