You probably know exactly what it’s like to feel stress, but what you may not know is that it can objectively influence your health. Answers to questions like “How stressed do you feel?” or “How overwhelmed do you feel?” can predict your likelihood of developing both minor illnesses and serious problems like future heart attack (Cohen et al., 2007). To understand how health psychologists study these types of associations, we will describe one famous example of a stress and health study. Imagine that you are a research subject for a moment. After you check into a hotel room as part of the study, the researchers ask you to report your general levels of stress. Not too surprising; however, what happens next is that you receive droplets of cold virus into your nose! The researchers intentionally try to make you sick by exposing you to an infectious illness. After they expose you to the virus, the researchers will then evaluate you for several days by asking you questions about your symptoms, monitoring how much mucus you are producing by weighing your used tissues, and taking body fluid samples—all to see if you are objectively ill with a cold. Now, the interesting thing is that not everyone who has drops of cold virus put in their nose develops the illness. Studies like this one find that people who are less stressed and those who are more positive at the beginning of the study are at a decreased risk of developing a cold (Cohen et al., 1991, 2006) (see Figure \(\PageIndex{1}\)for an example).
Figure \(\PageIndex{1}\): Positive correlation between test subjects’ stress levels and their tendency to develop a cold. [“Stress and Cold Development” by Judy Schmitt is licensed under CC BY-NC-SA 4.0. Adapted from Cohen et al. (1991).
Importantly, it is not just major life stressors (e.g., a family death, a natural disaster) that increase the likelihood of get- ting sick. Even small daily hassles like getting stuck in traffic or fighting with your girlfriend can raise your blood pressure, alter your stress hormones, and even suppress your immune system function (DeLongis et al., 1988; Twisk et al., 1999).
It is clear that stress plays a major role in our mental and physical health, but what exactly is it? The term stress was originally derived from the field of mechanics where it is used to describe materials under pressure. The word was first used in a psychological manner by researcher Hans Selye. He was examining the effect of an ovarian hormone that he thought caused sickness in a sample of rats. Surprisingly, he noticed that almost any injected hormone produced this same sick- ness. He smartly realized that it was not the hormone under investigation that was causing these problems, but instead, the aversive experience of being handled and injected by researchers that led to high physiological arousal and, eventually, to health problems like ulcers. Selye (1946) coined the term stressor to label a stimulus that had this effect on the body and developed a model of the stress response called the general adaptation syndrome. Since then, psychologists have studied stress in a myriad of ways, including stress as negative events (e.g., natural disasters or major life changes like dropping out of school), as chronically difficult situations (e.g., taking care of a loved one with Alzheimer’s), as short- term hassles, as a biological fight-or-flight response, and even as clinical illness like post-traumatic stress disorder (PTSD). It continues to be one of the most important and well-studied psychological correlates of illness, because excessive stress causes potentially damaging wear and tear on the body and can influence almost any imaginable disease process.
