The antonyms for the phrase "lighting up on" depend on the context in which it is used. If it refers to the act of smoking a cigarette or a joint, antonyms could include refraining, abstaining, or quitting. In the context of illuminating a space, antonyms could include darkening or dimming. In a metaphorical sense, antonyms could include dampening, suppressing, or repressing emotions or excitement. It is important to understand the specific usage of the phrase to fully grasp the appropriate antonyms. Regardless of the context, however, the antonyms imply a contrast to the act or event of "lighting up on.