A delta-wave inducer was a device which promoted the generation of delta waves in many humanoid, leading to a state of deep sleep. It was commonly used to render a patient unconscious during surgery, as it also increased the body's natural endorphin production. Dr. Julian Bashir used a delta-wave inducer during the procedure to remove the Dax symbiont from Jadzia Dax in 2370, and place it instead in a new host, Verad. (DS9 episode: "Invasive Procedures")