"one's mental faculties, conscious cognitive powers, sanity," 1560s, from sense (n.). The meaning "faculties of physical sensation" is from 1590s.
1737, "disturbance of regular order," from French dérangement (17c.), from déranger (see derange). Mental sense "disturbance of the intellect or reason" is from 1800.
"having control of one's mental faculties, self-possessed," c. 1600, past-participle adjective from collect (v.). Related: Collectedness.