A quantitative electroencephalograph (QEEG) based method and system for automatically controlling anesthesia is called a Closed Loop Anesthesia Controller (CLAC). An anesthetic is administered until the patient has attained the desired plane of anesthesia and a QEEG self-norm is then obtained. If the patient's brain waves exceed a confidence interval, centered at the set-point of the self-norm, the administration of the anesthesia is automatically adjusted.