The term gaslighting comes from the 1938 play by Patrick Hamiltion, known in America as "Angel Street" and later developed into the film "Gas Light" by Alfred Hitchcock.

In the suspense film, a manipulative husband tries to make his wife think she is losing her mind by making subtle changes in her environment, including slowly and steadily dimming the flame on a gas lamp.

Not only does he disrupt her environment and make her believe she is insane, but he also abuses and controls her, cutting her off from family and friends.

Consequently, the wife is constantly second-guessing herself, her feelings, her perceptions, and her memories. Additionally, she feels neurotic, hypersensitive, and out-of-control, which is the goal of gaslighting—to leave the target feeling off-kilter and unsure of what is true and what isn’t.

Because this film was an accurate portrayal of the controlling and toxic actions that manipulative people use, psychologists and counselors began to label this type of emotionally abusive behavior "gaslighting."