From Wikipedia
Health psychology is concerned with understanding how biology, behavior, and social context influence health and illness. Health psychologists work alongside other medical professionals in clinical settings, work on behaviour change in public health promotion, teach at universities, and conduct research. Although its early beginnings can be traced to the kindred field of clinical psychology, four different divisions within health psychology and one allied field have developed over time. The four divisions include clinical health psychology, public health psychology, community health psychology, and critical health psychology. The allied field is occupational health psychology. Organizations closely associated with the field of health psychology include Division 38 of the American Psychological Association and the Division of Health Psychology of the British Psychological Society.