Simpson completed his training in exercise physiology and immunology at Edinburgh Napier University in Scotland before spending nine years as a faculty member at the University of Houston. He studies the effects of exercise and stress on the immune system. Major cross-cutting themes of his work are aging immunosenescence) cancer and spaceflight. Specifically, Dr Simpson and his team study how single exercise bouts can be used to augment the recovery and expansion of specific immune cells that can be used therapeutically to treat patients with hematologic malignancies; and how exercise can be used to negate the onset of immunosenescence during natural aging. He is also interested in how exercise training can contribute to improved patient survival and quality of life through immune and inflammatory pathways at all phases of the cancer care continuum. His current work includes four NASA funded projects that aim to examine the impact of long duration spaceflight and extreme isolation on astronaut immune function and illness rates, and the effects of simulated microgravity on viral infectivity and host immune evasion. Dr. Simpson is also investigating how certain viral infections can protect patients from relapse following hematopoietic stem cell transplantation in a project that has been funded by the National Cancer Institute. Dr. Simpson is a Fellow of the American College of Sports Medicine ACSM) a member of the Psycheneuroimmunology Research Society PNIRS) and an honorary board member of the International Society of Exercise and Immunology ISEI) He is Associate Editor of the ISEI journal Exercise Immunology Reviews, and is on the editorial board of the journals Brain, Behavior and Immunity, Inflammopharmacology and American Journal of Lifestyle Medicine.