1. Don't stay up too late.

别熬太晚！

2. Time for bed.

该上床睡觉了。

3. Why are you still up?

你怎么还不睡？

4. You should go to bed early.

你应该早点睡。

5. You should have an early night.

你应该早点睡。

6. Go to sleep.

快点儿睡！

7. Let's turn in early.

咱们早点睡吧！

8. It's time to hit the sack.

该睡觉了。

注：to hit the sack只能指结束一天工作和学习后晚上去睡觉，午睡也不能用这个短语来表达。

9. You should keep early hours.

你应该早睡早起。

注：to keep early hours指养成早睡早起的习惯，偶尔早起不能使用这个短语。