It was a regular Tuesday morning in New York City. College students were sitting in their morning classes. People were arriving at work and the streets were beginning to fill with shoppers and tourists. Then, at 8:46 a.m., American Airlines Flight 11 crashed into the North Tower of the World Trade Center. People watched in horror. This seemed like a terrible accident. Then at 9:03 a.m., United Airlines Flight 175 crashed into the South Tower of the World Trade Center. There were then reports of a plane crashing into the Pentagon. And another somewhere in Pennsylvania. America was under attack, and no one knew what would happen next on this terrifying morning of September 11, 2001. The terrorist attacks on the World Trade Center were an enormous stressor that had a lasting impact on many people, physically and psychologically. People living in close proximity to the World Trade Center (within 1.5 miles) during 9/11 were found to have less gray matter in the amygdala, hippocampus, insula, anterior cingulate, and medial prefrontal cortex relative to those living more than 200 miles away during the attacks, suggesting that the stress associated with the attacks may have reduced the size of these parts of the brain that play an important role in emotion, memory, and decision making (Ganzel et al., 2008). Children who watched more television coverage of 9/11 had higher symptoms of posttraumatic stress disorder than children who watched less coverage (Otto et al., 2007). Stress can produce changes in every system of the body and mind, stimulating both physical reactions and psychological reactions. Let’s consider each in turn.

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The fight-or-flight response is an emotional and physiological reaction to an emergency that increases readiness for action. The mind asks, “Should I stay and battle this somehow, or should I run like mad?” And the body prepares to react. If you’re a cat at this time, your hair stands on end. If you’re a human, your hair stands on end, too, but not as visibly.

Brain activation in response to threat occurs in the hypothalamus, initiating a cascade of bodily responses that include stimulation of the nearby pituitary gland, which in turn causes stimulation of the adrenal glands (see FIGURE 13.1). This pathway is sometimes called the HPA (hypothalamic–pituitary–adrenocortical) axis. The adrenal glands release hormones, including the catecholamines (epinephrine and norepinephrine), which increase sympathetic nervous system activation (and therefore increase heart rate, blood pressure, and respiration rate) and decrease parasympathetic activation (see the Neuroscience and Behavior chapter). The increased respiration and blood pressure make more oxygen available to the muscles to energize attack or to initiate escape. The adrenal glands also release cortisol, a hormone that increases the concentration of glucose in the blood to make fuel available to the muscles. Everything is prepared for a full-tilt response to the threat.

General Adaptation Syndrome

What might have happened if the terrorist attacks of 9/11 were spaced out over a period of days or weeks? In the 1930s, Canadian physician Hans Selye subjected rats to heat, cold, infection, trauma, hemorrhage, and other prolonged stressors, and he found that the stressed-out rats developed physiological responses that included an enlarged adrenal cortex, shrinking of the lymph glands, and ulceration of the stomach. Noting that many different kinds of stressors caused similar patterns of physiological change, he called the reaction the general adaptation syndrome (GAS), a three-stage physiological stress response that appears regardless of the stressor that is encountered. The GAS occurs in three phases (see FIGURE 13.2). First comes the alarm phase (equivalent to the fight-or-flight response), in which the body rapidly mobilizes its resources to respond to the threat. Next, in the resistance phase, the body tries to adapt and cope with its stressor by shutting down unnecessary processes such as digestion, growth, and the sex drive. If the GAS continues long enough, the exhaustion phase sets in: the body’s resistance collapses, creating damage that can include susceptibility to infection, tumor growth, aging, irreversible organ damage, or death.

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Stress Effects on Health and Aging

As people age, the body slowly begins to break down (just ask any of the authors of this book). Interestingly, recent research has revealed that stress significantly accelerates the aging process. Elizabeth Smart’s parents noted that, upon being reunited with her after 9 months of separation, they almost did not recognize her because she appeared to have aged so much (Smart, Smart, & Morton, 2003). More generally, people exposed to chronic stress, whether due to their relationships, job, or something else, experience actual wear and tear on their bodies and increased aging. Take a look at the pictures of the past three presidents before and after their terms as president of the United States (arguably, one of the most stressful jobs in the world). As you can see, they appear to have aged much more than the 4–8 years that passed between their first and second photographs.

Why does stress increase the aging process? The cells in our bodies are constantly dividing, and as part of this process, our chromosomes are repeatedly copied so that our genetic information is carried into the new cells. This process is facilitated by the presence of telomeres, caps at the ends of each chromosome that protect the ends of chromosomes and prevent them from sticking to each other. They are kind of like the tape at the end of your shoelaces that keeps them from being frayed and not working as efficiently. Each time a cell divides, the telomeres become slightly shorter. Over time, if the telomeres become too short, cells can no longer divide, and this can lead to the development of tumors and a range of diseases. The recent discovery of the function of telomeres and their relation to aging and disease has been one of the most exciting advances in science in the past several decades.

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Interestingly, social stressors can play an important role in this process. People exposed to chronic stress have shorter telomere lengths (Epel et al., 2004). Laboratory studies suggest that increased cortisol can lead to shortened telomeres, which has downstream negative effects in the form of accelerated aging and increased risk of a wide range of diseases, including cancer, cardiovascular disease, diabetes, and depression (Blackburn & Epel, 2012). The good news is that activities like exercise and meditation seem to prevent chronic stress from shortening telomere length, providing a potential explanation of how these activities may convey health benefits such as longer life and lower risk of disease (Epel et al., 2009; Puterman et al., 2010).

Stress Effects on the Immune Response

The immune system is a complex response system that protects the body from bacteria, viruses, and other foreign substances. The immune system is remarkably responsive to psychological influences. Stressors can cause hormones known as glucocorticoids to flood the brain (described in the Neuroscience and Behavior chapter), wearing down the immune system and making it less able to fight invaders (Webster Marketon & Glaser, 2008). For example, in one study, medical student volunteers agreed to receive small wounds to the roof of the mouth. Researchers observed that these wounds healed more slowly during exam periods than during summer vacation (Marucha, Kiecolt-Glaser, & Favagehi, 1998).

The effect of stress on immune response may help to explain why social status is related to health. Studies of British civil servants beginning in the 1960s found that mortality varied precisely with civil service grade: the higher the classification, the lower the death rate, regardless of cause (Marmot et al., 1991). One explanation is that people in lower-status jobs more often engage in unhealthy behavior such as smoking and drinking alcohol, and there is evidence of this. But there is also evidence that the stress of living life at the bottom levels of society may increase risk of infections by weakening the immune system. People who perceive themselves as low in social status are more prone to suffer from respiratory infections, for example, than those who do not bear this social burden—and the same holds true for low-status male monkeys (Cohen, 1999).

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Stress and Cardiovascular Health

The heart and circulatory system are also sensitive to stress. Chronic stress is a major contributor to coronary heart disease (Krantz & McCeney, 2002), because prolonged stress-activated arousal of the sympathetic nervous system raises blood pressure and gradually damages the blood vessels. The damaged vessels accumulate plaque, and the more plaque, the greater the likelihood of coronary heart disease. In one study, men who exhibited elevated blood pressure in response to stress and who reported that their work environment was especially stressful showed progressive atherosclerosis during the 4-year study (Everson et al., 1997).

In the 1950s, cardiologists interviewed and tested 3,000 healthy middle-aged men and then tracked their subsequent cardiovascular health (Friedman & Rosenman, 1974). Some of the men displayed a Type A behavior pattern, a tendency toward easily aroused hostility, impatience, a sense of time urgency, and competitive achievement strivings. Other men displayed a less driven behavior pattern (sometimes called Type B). The Type A men were identified by their answers to questions in the interview (agreeing that they walk and talk fast, work late, set goals for themselves, work hard to win, and easily get frustrated and angry at others), and also by the pushy and impatient way in which they answered the questions. In the decade that followed, men who had been classified as Type A were twice as likely to have heart attacks as the Type B men.

The body’s response to stress is intertwined with responses of the mind. Perhaps the first thing the mind does is try to sort things out—to interpret whether an event is threatening or not—and if it is, whether something can be done about it.

Stress Interpretation

The interpretation of a stimulus as stressful or not is called primary appraisal (Lazarus & Folkman, 1984). Primary appraisal allows you to realize that a small dark spot on your shirt is a stressor (spider!) or that a 70-mile-per-hour drop from a great height in a small car full of screaming people may not be (roller coaster!).

The next step in interpretation is secondary appraisal, determining whether the stressor is something you can handle or not—that is, whether you have control over the event (Lazarus & Folkman, 1984). Interestingly, the body responds differently depending on whether the stressor is perceived as a threat (a stressor you believe you might not be able to overcome) or a challenge (a stressor you feel fairly confident you can control; Blascovich & Tomaka, 1996). The same midterm exam is seen as a challenge if you are well prepared, but it is a threat if you didn’t study. Although both threats and challenges raise heart rate, threats increase vascular reactivity (such as constriction of the blood vessels, which can lead to high blood pressure; see the Hot Science box in Section 13.1).

Burnout

Did you ever take a class from an instructor who had lost interest in the job? The syndrome is easy to spot: The teacher looks distant and blank, almost robotic, giving predictable and humdrum lessons each day, as if it doesn’t matter whether anyone is listening. Now imagine being this instructor. You decided to teach because you wanted to shape young minds. You worked hard, and for a while, things were great. But one day, you looked up to see a room full of miserable students who were bored and didn’t care about anything you had to say. They updated their Facebook pages while you talked and started putting things away long before the end of class. You’re happy at work only when you’re not in class. When people feel this way, especially about their careers, they are suffering from burnout, a state of physical, emotional, and mental exhaustion created by long-term involvement in an emotionally demanding situation and accompanied by lowered performance and motivation.

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Burnout is a particular problem in the helping professions (Maslach, Schaufeli, & Leiter, 2001). Teachers, nurses, clergy, doctors, dentists, psychologists, social workers, police officers, and others who repeatedly encounter emotional turmoil on the job may only be able to work productively for a limited time before succumbing to burnout (Maslach, 2003). Their unhappiness can even spread to others; people with burnout tend to become disgruntled employees who revel in their co-workers’ failures and ignore their co-workers’ successes (Brenninkmeijer, Vanyperen, & Buunk, 2001).

What causes burnout? One theory suggests that the culprit is using your job to give meaning to your life (Pines, 1993). If you define yourself only by your career and gauge your self-worth by success at work, you risk having nothing left when work fails. For example, a teacher in danger of burnout might do well to invest time in family, hobbies, or other self-expressions. Others argue that some emotionally stressful jobs lead to burnout no matter how they are approached, and active efforts to overcome the stress before burnout occurs are important. The stress management techniques discussed in the next section may be lifesavers for people in such jobs.