To stay up late, studying or working. This expression, which may well be as old as the first oil lamp, appeared in English in the mid-seventeenth century. It has been traced to a poem by Francis Quarles (“Emblems,” 1635): “Wee spend our midday sweat, or midnight oyle; wee tyre the night in thought; the day in toyle.” A more recent example is found in David Baldacci’s Hour Game (2004): “You don’t want to burn the midnight oil too much; it’s bad for your complexion.”