O’Reilly started his research career as a lab apprentice at Georgetown University Medical School in Washington, D.C. He also spent time as a lab tech at Johns Hopkins Medical School in Baltimore, Maryland with Dr. Larry Schramm, where he was introduced and trained to study and record from voltage-gated Na+ channels. He then pursued and received his MS and PhD degrees in Neuroscience and Biophysics from Yale University and Medical School, New Haven, CT. The research for this degree focused on the structure & function of voltage-gated Na+ channels. This was followed by post-doctoral work at the Brigham & Women's Hospital & Harvard Medical School, Boston, MA.
Current research at Southeastern continues on this research in the laboratory looking at structure-function analysis of slow inactivation in voltage- gated Na+ channels. He has continued this research at Southeastern since 2003.
Teaching duties include Anatomy & Physiology courses primarily for Nursing and Kinesiology students, and Animal Behavior and Neuroscience courses primarily for upper-level Biology majors.