General "sleep":
* 睡 (shuì): This is the most common and general way to say "sleep." You can use it in most situations.
* 睡觉 (shuì jiào): This literally means "sleep sleep" and is also a common way to say "sleep." It emphasizes the action of sleeping.
"Go to sleep":
* 睡觉 (shuì jiào): This can also be used to mean "go to sleep."
* 睡 (shuì): This is a more concise way to say "go to sleep."
"Sleep well":
* 睡好 (shuì hǎo): This is a polite way to wish someone good night.
Examples:
* 我要睡觉了。 (Wǒ yào shuì jiào le.) - I'm going to sleep.
* 你睡了吗？ (Nǐ shuì le ma?) - Did you sleep?
* 晚安，睡好。 (Wǎn ān, shuì hǎo.) - Good night, sleep well.
The best way to choose the right word depends on the situation and the level of formality.