Sleep tight = Sleep well = Have a good dream = 안녕히 주무세요 = 잘자요 = 잘자 = 좋은 꿈꿔 = 숙면하세요
잘 자세요 => This sounds very weird at least to me since it is in between being polite and casual. For learners of Korean language, I do not recommend the use of such pseud- polite or pseudo-casual form.
Polite form of sleep tight: 안녕히 주무세요 = 잘자요=쉬세요 (Have a rest) Casual form: 잘자 = 좋은 꿈꿔=잘 쉬어 (Have a rest)
a way to say goodbye to someone at night. => 좋은 밤 되세요 (Have a good night)