sleep on something

sleep on (something)

To postpone a decision until the following day so that one has additional time to consider it. Why don't you sleep on the offer and let us know your decision in the morning? I'm still not sure if I'm ready to spend that much money. Can I sleep on it?
See also: on, sleep

sleep on something

Consider something overnight before deciding, as in I don't know if I want to go on such a long hike; let me sleep on it. This usage was first recorded in 1519 in the state papers of King Henry VIII: "His Grace ... said that he would sleep and dream upon the matter."
See also: on, sleep, something