Used when someone needs extra time to think before making a choice. Let me sleep on it, and I'll get back to you tomorrow with my answer.
Pro Tip 2/3
Not Immediate
Indicates the decision will not be made right now, reinforcing patience is involved. I can't give you an immediate response; I need to sleep on it.
Pro Tip 3/3
Serious Consideration
Shows that the matter is significant and the decision requires careful thought. This is a big commitment, so I'll have to sleep on it before saying yes.