Imagery involves the use of mental visualization and imagination to enhance relaxation and alter specific experiences. It may include direct suggestion. Individuals may use recorded scripts to guide the creation of mental images. Guided imagery can integrate techniques founded in multiple psychological theories and hypnotherapy, and it is often combined with the technique of progressive muscle relaxation. Imagery alone has been examined for effectiveness in patients with cancer for chemotherapy-induced nausea and vomiting, chronic pain, sleep-wake disturbances, and cognitive impairment.