Good night in Korean
Most sources suggest 잘자요 and similar expressions as standard for "good night" in Korean, but doesn't that only make sense if the person you're talking to is going to sleep? If I'm the one who's going to sleep, can I still use 잘자요? It sounds weird to me, as if you'd be wishing yourself a good night.

Question

Answer

The Korean language doesn't really have an evening/nighttime greeting, only the one you already know used before bed time (i.e. 잘자, 잘자요, 안녕히 주무세요, etc.).

If you want to say "good night" but not right before bed time, you could use alternate phrases like 안녕히계세요/가세요, 먼저 가보겠습니다, 쉬세요, etc.