The term "gaslighting" has its origins in a play called "Gas Light," written by Patrick Hamilton in 1938. The play was later adapted into two films, "Gaslight" in 1940 and "Gaslight" again in 1944. The story revolves around a husband who manipulates his wife into believing she is going insane by dimming the gas lights in their home and then denying that the lights are changing.  The husband's goal is to make his wife question her own perception and sanity, creating a sense of confusion and self-doubt. The term "gaslighting" has since been adopted to describe psychological manipulation where one person seeks to gain control over another by causing them to doubt their reality, memories, or sanity. It's commonly used in the context of emotionally abusive relationships.