health psychology health psychology health psychology is the study of psychological and behavioral processes in health, illness, and healthcare. the discipline is concerned with understanding how psychological, behavioral, and cultural factors contribute to physical health and illness. psychological factors can affect health directly. for example, chronically occurring environmental stressors affecting the hypothalamic–pituitary–adrenal axis, cumulatively, can harm health. behavioral factors can also affect a person's health. for example, certain behaviors can, over time, harm (smoking or consuming excessive amounts of alcohol) or enhance (engaging in exercise) health. health psychologists take a biopsychosocial approach. in other words, health psychologists understand health to be the product not only of biological processes (e.g., a virus, tumor, etc.) but also of psychological (e.g., thoughts and beliefs), behavioral (e.g., habits), and social processes (e.g., socioeconomic status and ethnicity). part of a series onpsychology outline history subfields basic types abnormal behavioral behavioral genetics biological cognitive/cognitivism comparative cross-cultural cultural developmental differential evolutionary experimental mathematical neuropsychology personality positive psychodynamic psychometrics quantitative social applied psychology applied behavior analysis clinical community consumer counseling critical educational environmental ergonomics food forensic health humanistic industrial and organizational legal medical military music occupational health political psychometrics religion school sport traffic lists disciplines organizations psychologists psychotherapies research methods theories timeline topics psychology portal by understanding psychological factors that influence health, and constructively applying that knowledge, health psychologists can improve health by working directly with individual patients or indirectly in large-scale public health programs. in addition, health psychologists can help train other healthcare professionals (e.g., physicians and nurses) to apply the knowledge the discipline has generated, when treating patients. health psychologists work in a variety of settings: alongside other medical professionals in hospitals and clinics, in public health departments working on large-scale behavior change and health promotion programs, and in universities and medical schools where they teach and conduct research. although its early beginnings can be traced to the field of clinical psychology, four different divisions within health psychology and one related field, occupational health psychology (ohp), have developed over time. the four divisions include clinical health psychology, public health psychology, community health psychology, and critical health psychology. professional organizations for the field of health psychology include division 38 of the american psychological association (apa), the division of health psychology of the british psychological society (bps), the european health psychology society, and the college of health psychologists of the australian psychological society (aps). advanced credentialing in the us as a clinical health psychologist is provided through the american board of professional psychology. overview recent advances in psychological, medical, and physiological research have led to a new way of thinking about health and illness. this conceptualization, which has been labeled the biopsychosocial model, views health and illness as the product of a combination of factors including biological characteristics (e.g., genetic predisposition), behavioral factors (e.g., lifestyle, stress, health beliefs), and social conditions (e.g., cultural influences, family relationships, social support). psychologists who strive to understand how biological, behavioral, and social factors influence health and illness are called health psychologists. health psychologists use their knowledge of psychology and health to promote general well-being and understand physical illness. they are specially trained to help people deal with the psychological and emotional aspects of health and illness. health psychologists work with many different health care professionals (e.g., physicians, dentists, nurses, physician's assistants, dietitians, social workers, pharmacists, physical and occupational therapists, and chaplains) to conduct research and provide clinical assessments and treatment services. many health psychologists focus on prevention research and interventions designed to promote healthier lifestyles and try to find ways to encourage people to improve their health. for example, they may help people to lose weight or stop smoking. health psychologists also use their skills to try to improve the healthcare system. for example, they may advise doctors about better ways to communicate with their patients. health psychologists work in many different settings including the uk's national health service (nhs), private practice, universities, communities, schools and organizations. while many health psychologists provide clinical services as part of their duties, others function in non-clinical roles, primarily involving teaching and research. leading journals include health psychology, the journal of health psychology, the british journal of health psychology, and applied psychology: health and well-being. health psychologists can work with people on a one-to-one basis, in groups, as a family, or at a larger population level. health psychology, like other areas of applied psychology, is both a theoretical and applied field. health psychologists employ diverse research methods. these methods include controlled randomized experiments, quasi-experiments, longitudinal studies, time-series designs, cross-sectional studies, case-control studies, qualitative research as well as action research. health psychologists study a broad range of health phenomena including cardiovascular disease (cardiac psychology), smoking habits, the relation of religious beliefs to health, alcohol use, social support, living conditions, emotional state, social class, and more. some health psychologists treat individuals with sleep problems, headaches, alcohol problems, etc. other health psychologists work to empower community members by helping community members gain control over their health and improve quality of life of entire communities. clinical health psychology (clhp) clhp is the application of scientific knowledge, derived from the field of health psychology, to clinical questions that may arise across the spectrum of health care. clhp is one of the specialty practice areas for clinical and health psychologists. it is also a major contributor to the prevention-focused field of behavioral health and the treatment-oriented field of behavioral medicine. clinical practice includes education, the techniques of behavior change, and psychotherapy. in some countries, a clinical health psychologist, with additional training, can become a medical psychologist and, thereby, obtain prescription privileges. public health psychology (php) php is population-oriented. a major aim of php is to investigate potential causal links between psychosocial factors and health at the population level. public health psychologists present research results to educators, policy makers, and health care providers in order to promote better public health. php is allied to other public health disciplines including epidemiology, nutrition, genetics and biostatistics. some php interventions are targeted toward at-risk population groups (e.g., undereducated, single pregnant women who smoke) and not the population as a whole (e.g., all pregnant women). community health psychology (cohp) cohp investigates community factors that contribute to the health and well-being of individuals who live in communities. cohp also develops community-level interventions that are designed to combat disease and promote physical and mental health. the community often serves as the level of analysis, and is frequently sought as a partner in health-related interventions. critical health psychology (crhp) crhp is concerned with the distribution of power and the impact of power differentials on health experience and behavior, health care systems, and health policy. crhp prioritizes social justice and the universal right to health for people of all races, genders, ages, and socioeconomic positions. a major concern is health inequalities. the critical health psychologist is an agent of change, not simply an analyst or cataloger. a leading organization in this area is the international society of critical health psychology. occupational health psychology pickren and degni and sanderson observed that in europe and north america, occupational health psychology (ohp) emerged as a specialty with its own organizations. the authors noted that ohp owes some of that emergence to health psychology as well as other disciplines (e.g., i/o psychology, occupational medicine). sanderson underlined examples in which ohp aligns with health psychology, including adkins's research. adkins documented the application of behavioral principles to improve working conditions, mitigate job stress, and improve worker health in a complex organization. origins and development health psychology developed in different forms in different societies. psychological factors in health had been studied since the early 20th century by disciplines such as psychosomatic medicine and later behavioral medicine, but these were primarily branches of medicine, not psychology. united states in 1969, william schofield prepared a report for the apa entitled the role of psychology in the delivery of health services. while there were exceptions, he found that the psychological research of the time frequently regarded mental health and physical health as separate, and devoted very little attention to psychology's impact upon physical health. one of the few psychologists working in this area at the time, schofield proposed new forms of education and training for future psychologists. the apa, responding to his proposal, in 1973 established a task force to consider how psychologists could (a) help people to manage their health-related behaviors, (b) help patients manage their physical health problems, and (c) train healthcare staff to work more effectively with patients. health psychology began to emerge as a distinct discipline of psychology in the united states in the 1970s. in the mid-20th century there was a growing understanding in medicine of the effect of behavior on health. for example, the alameda county study, which began in the 1960s, showed that people who ate regular meals (e.g., breakfast), maintained a healthy weight, received adequate sleep, did not smoke, drank little alcohol, and exercised regularly were in better health and lived longer. in addition, psychologists and other scientists were discovering relationships between psychological processes and physiological ones. these discoveries include a better understanding of the impact of psychosocial stress on the cardiovascular and immune systems, and the early finding that the functioning of the immune system could be altered by learning. led by joseph matarazzo, in 1977, apa added a division devoted to health psychology. at the first divisional conference, matarazzo delivered a speech that played an important role in defining health psychology. he defined the new field in this way, "health psychology is the aggregate of the specific educational, scientific and professional contributions of the discipline of psychology to the promotion and maintenance of health, the prevention and treatment of illness, the identification of diagnostic and etiologic correlates of health, illness and related dysfunction, and the analysis and improvement of the healthcare system and health policy formation." in the 1980s, similar organizations were established elsewhere. in 1986, the bps established a division of health psychology. the european health psychology society was also established in 1986. similar organizations were established in other countries, including australia and japan. universities began to develop doctoral-level training programs in health psychology. in the us, post-doctoral level health psychology training programs were established for individuals who completed a doctoral degree in clinical psychology. united kingdom psychologists have been working in medical settings for many years (in the uk sometimes the field was termed medical psychology). medical psychology, however, was a relatively small field, primarily aimed at helping patients adjust to illness. the bps's reconsideration of the role of the medical section prompted the emergence of health psychology as a distinct field. marie johnston and john weinman argued in a letter to the bps bulletin that there was a great need for a health psychology section. in december 1986 the section was established at the bps london conference, with marie johnston as chair. at the annual bps conference in 1993 a review of "current trends in health psychology" was organized, and a definition of health psychology as "the study of psychological and behavioural processes in health, illness and healthcare" was proposed. the health psychology section became a special group in 1993 and was awarded divisional status within the uk in 1997. the awarding of divisional status meant that the individual training needs and professional practice of health psychologists were recognized, and members were able to obtain chartered status with the bps. the bps went on to regulate training and practice in health psychology until the regulation of professional standards and qualifications was taken over by statutory registration with the health professions council in 2010. a number of relevant trends coincided with the emergence of health psychology, including: epidemiological evidence linking behavior and health. the addition of behavioral science to medical school curricula, with courses often taught by psychologists. the training of health professionals in communication skills, with the aim of improving patient satisfaction and adherence to medical treatment. increasing numbers of interventions based on psychological theory (e.g., behavior modification). an increased understanding of the interaction between psychological and physiological factors leading to the emergence of psychophysiology and psychoneuroimmunology (pni). the health domain having become a target of research by social psychologists interested in testing theoretical models linking beliefs, attitudes, and behavior. the emergence of aids/hiv, and the increase in funding for behavioral research the epidemic provoked. the