What does it mean word for word?
The phrase is composed of the adverb 잘 (well) and the verb 자 (sleep).
Is there a formal and an informal way to say it?
The default form 잘 자 is informal and should only be used with friends, siblings or people younger than you. For a polite version suitable for people you are not close with or are slightly older than you, use 잘 자요. To say 'have a good sleep' to an elder or someone in a higher social position, use 안녕히 주무세요. The phrase 잘 주무세요 is a formal way to wish someone a good sleep.
How does it change in a sentence?
Adding the particle 요 to the end of 잘 자 makes it a polite form suitable for people you are not close with or are slightly older than you.
How do you pronounce it?
jal ja
When do people say it?
One can say 안녕히 주무세요 선생님 when speaking to a teacher. One can say 안녕히 주무세요 아저씨 when addressing an older person. The phrase 안녕히 주무세요, 좋은 꿈 꾸세요 means 'have a good sleep, have sweet dreams'.
Did you know?
- The more formal phrase 안녕히 주무세요 uses the word 안녕히, which is the same word used to say 'goodbye' in a formal setting, meaning 'peacefully'.
- The polite verb 주무시다 used in 안녕히 주무세요 is a completely different word from 자다 used in 잘 자, rather than just a grammatical change.
- In modern romantic Korean culture, couples often use 잘 자 combined with a heart emoji or a 'sweet dream' phrase to signify intimacy.
Examples in context
- 잘 자.jal ja.Have a good sleep.
- 내일 봐, 잘 자.naeil bwa, jal ja.See you tomorrow, sleep well.
Example conversation
Dohyun and Subin are saying goodbye before going to their own rooms.
- 도현 Do-hyeon수빈아, 이제 자러 갈게.Subin-a, ije jareo galge.Subin, I'm going to bed now.
- 수빈 Su-bin응, 도현아. 잘 자.eung, Dohyun-a. jal ja.Yeah, Dohyun. Have a good sleep.
- 도현 Do-hyeon너도 잘 자.neodo jal ja.You sleep well too.
- 수빈 Su-bin내일 아침에 만나자.naeil achime mannaja.Let's meet tomorrow morning.
Sources
- Pronunciation: Wiktionary entry 잘 자, CC BY-SA 4.0, dump of 2026-09-26.
