Always on. No aspect or detail of the face ever disappears. The face doesn’t “light up” like an Apple or other similar smart watches. The screen is brilliant and best in the brightest light (direct sunlight). In a dark room or at night push the side button, touch the screen or shake the watch and a back light will temporarily illuminate the screen. The only way the screen can ever go blank is by turning the watch completely off. Eventually this technology should replace the lift or shake to illuminate tech. That’s why the battery lasts several days instead of several hours between charges.