For Tomb Guards, it means a jarring break from the 'normal' routine of 21 steps, heel clicks, and guard changes.
What Daisey relates in the show is jarring; he describes seeing abusive working conditions, disfigurement, child labor, illness.
As a neonatal physician trained in the United States, it is a jarring process for me to practice medicine here.
1520s, "to make a harsh, grating sound," usually said to be echoic or imitative, but no one explains how, or of what. Figurative sense of "have an unpleasant effect on" is from 1530s; that of "cause to vibrate or shake" is from 1560s. Related: Jarred; jarring.
"cylindrical vessel," early 15c., possibly from Middle French jarre "liquid measure" (smaller than a barrel), 12c., from Provençal jarra, from Arabic jarrah "earthen water vessel" (whence also Spanish jarra, Italian giarra) [Klein].