Let me sleep on it. I'll let you know tomorrow.

让我考虑一下，明天告诉你。

let me sleep on it.让我好好考虑考虑。例：Let me sleep on it. I need some more ideas.让我考虑一下，我想再收集一下各方面的建议。It's a sudden question. Let me sleep on it.这个问题对我来讲挺突然，让我考虑一下。