This chapter reviews Cranial Electrotherapy Stimulation (CES) studies appearing in the United States (US) literature, plus those few published outside the US that appears in the current collection of the National Library of Medicine. It discusses human studies since these have built upon old animal studies in most cases and more readily show the state of CES as a treatment modality. Neuro Systems provides paste-on electrodes that are about the size of a nickel and are placed at the same point, but held in place by adhesive pads. Insomnia is a more difficult problem to decipher. The amount of current found passing the electrodes was considered sufficient to elicit physiological response in brain tissue. Only a limited number of biochemical studies have appeared in the CES literature in the US to date. Due to superimposition of terms, they frequently believe that sham-treated controls measure the placebo effect.