Gaslighting is a manipulation strategy that makes someone question their self-worth and sanity. The term is derived from the 1930s play Gas Light, in which a husband makes his wife doubt her perception by manipulating the gas light but claiming to see nothing out of the ordinary himself. In a work environment, gaslighting can make someone feel incompetent or unimportant, like they can’t do anything right. They can feel like they don’t understand what’s going on around them or what’s expected of them. Gaslighting can come from a variety of people—a power-hungry manager, a competitive coworker, or a condescending client.