Chronic pain is a severe disabling problem within society, affecting 25-30% of the United States population.. Transcranial alternating current stimulation (tACS) has the potential to provide a treatment option that is safe, scientifically-supported, low-cost, and easy-to-administer method to effectively reduce symptoms in patients suffering from chronic pain. The purpose of this study is to test the feasibility of using tACS to treat patients with chronic pain, and to collect pilot efficacy as well as EEG and EKG biomarker data for optimizing the design of subsequent large-scale studies. The treatment rationale is to renormalize the presumed pathological structure of alpha oscillations in the prefrontal cortex (PFC) of patients with chronic pain.