Stress was originally defined by a Canadian biologist named Hans Selye (1907–1982) in the 1930s as a series of biochemical, nervous, digestive, and muscular responses in laboratory animals to a perceived threat, which he called a stressor. Selye later expanded the notion of stress to include humans trying to evaluate and respond to various stressors in their daily lives. Many people, however, use the word “stress” in casual
conversation to refer to almost any event or situation that worries or upsets them.
Some doctors distinguish several different types of stress according to whether the stress is positive or negative, or according to the length of time that the person experiences the stressor. In the 1970s, a psychologist named Richard Lazarus coined the term eustress to refer to stress that is good for health or leads to a sense of fulfillment. Increasing one's strength or endurance through active exercise would be an example of eustress, as would completing a course of study or finishing a job assignment.
Stress can also be categorized as acute, episodic acute, or chronic, according to the length of time the person feels stressed and whether the stress is a one-time event, repeated periodically, or long-term and unrelenting. An example of acute stress is facing a growling and aggressive-looking dog. Episodic acute stress includes the pressures that people place on themselves by taking on too many obligations or by not allowing enough time to complete tasks. Some jobs, such as police work or fire-fighting, involve episodic acute stress. Chronic stress is usually situational—the person is trapped in a bad marriage, a dead-end job, or living in a crime-ridden neighborhood.
In general, stress is a complicated set of physical and emotional responses to changes that occur in everyone's life. On the biological level, stress begins with the “fight-or-flight” reaction—the activation of a section of the brain called the hypothalamic-pituitary-adrenal system, or HPA. When a human perceives a situation as stressful, the HPA system releases cortisol, a steroid hormone. The next stage in the stress reaction is the release of neurotransmitters, or brain chemicals, that activate parts of the brain that register the emotion of fear. The neurotransmitters also suppress activity in parts of the brain associated with short-term memory, concentration, and rational thinking. This limitation allows a human to react quickly to a stressful situation but it also lowers his or her ability to deal with intellectual or social factors that may be part of the situation.
On the physical level, the person's heart rate and blood pressure rise; he or she breathes more rapidly, which allows the lungs to take in more oxygen. Blood flow to the muscles, lungs, and brain may increase by 300–400 percent. The spleen releases more blood cells into the
circulation, which increases the blood's ability to transport oxygen. The immune system redirects white blood cells to the skin, bone marrow, and lymph nodes. At the same time, nonessential body systems shut down. The skin becomes cool and sweaty as blood is drawn away from it toward the heart and muscles. The mouth becomes dry, and the digestive system slows down.
After the crisis passes, the levels of stress hormones drop and the body's various organ systems return to normal. This return is called the relaxation response. Some people are more vulnerable to stress than others because their hormone levels do not return to normal after a stressful event. In chronic stress, the organ systems of the body do not have the opportunity to return fully to normal levels. Different organs become under- or overactivated on a long-term basis. In time, these abnormal levels of activity can damage an organ or organ system.
What complicates the experience of stress is that different people respond differently to stressors. Some people find driving a highly stressful experience, for example, while others enjoy it. Similarly, some people enjoy the intellectual challenges of certain fields of study, while others are bored by them. Personality differences are another factor that influences people's response to stress. Some people are highly aggressive, inclined to worry, or easily irritated, while others are less competitive or more optimistic about life.
Almost everyone has experienced acute or episodic acute stressors. Some people, however, are more vulnerable than others to chronic stress-related illnesses:
- Children. Children have very little control over their environments. In addition, they are often unable to communicate their feelings accurately.
- Elderly adults. Aging appears to affect the body's response to stress, so that the relaxation response following a stressful event is slower and less complete. In addition, the elderly are often affected by such major stressors as health problems, the death of a spouse or close friends, and financial worries.
- Caregivers of mentally or physically disabled family members.
- Women in general.
- People with less education.
- People who belong to racial or ethnic groups that suffer discrimination.
- People who live in cities.
- People who are anger-prone. Chronic anger is associated with narrowing of the arteries, a factor in heart disease.
- People who lack supportive relatives or friends.
Stress is caused by the human body's response to any event or situation perceived as a stressor. Perception is an important factor in a person's reaction to stress because it can be modified or changed in some situations.
The specific symptoms of stress-related illness vary from person to person depending on which organs or body systems are most vulnerable. Common symptoms of stress include:
- Heart. Chronic stress raises blood pressure, triggers the release of cholesterol into the bloodstream, and causes the arteries to narrow. It also increases the possibility that a clot will form in the coronary arteries, thus increasing the person's risk of heart attack or stroke.
- Skin. Eczema and other allergic skin rashes can be triggered or made worse by stress.
- Digestive tract. Stress leads to nausea, diarrhea, constipation, bloating, and irritable bowel syndrome in many people. It may also play a role in the onset of eating disorders.
- Reproductive system. Stress can lead to loss of sexual desire in both men and women. In addition, stress during pregnancy is associated with a 50 percent higher risk of miscarriage. High stress levels on the mother during pregnancy are also related to higher rates of premature births and babies of lower than average birth weight; both are risk factors for infant mortality.
- Bones, joints, and muscles. Stress intensifies the chronic pain of arthritis and other joint disorders. It also produces tension-type headaches, which are headaches caused by the tightening of the muscles in the neck and scalp.
- Brain and central nervous system. Stress hormones released during acute stress interfere with memory and learning. People who are under severe stress become unable to concentrate; they may
become clumsy and accident-prone. Acute stress interferes with short-term memory, although this effect goes away after the stress is resolved. In children, however, the brain's biochemical responses to stress clearly limit the ability to learn.
- Immune system. Chronic stress increases a person's risk of getting an infectious illness. Several research studies have shown that people under chronic stress have lower than normal white blood cell counts and are more vulnerable to colds and influenza. Men with HIV infection and high stress levels progress more rapidly to AIDS than infected men with lower stress levels.
There is no specific test or imaging study for diagnosing stress. People with specific mental disorders like posttraumatic stress disorder (PTSD) or panic disorder can be diagnosed by a psychiatrist qualified to evaluate these conditions. In most other cases, however, a person is diagnosed in the course of a checkup for a stress-related physical condition when the doctor asks about the stress level in their living situation, school, or job.
Treatment for stress depends on the parts of the person's body that are affected and the sources of stress and types of stress in his or her life. Most people benefit from a combination of treatment approaches:
- Medications. These can be prescribed to treat physical conditions related to stress like high blood pressure or high cholesterol levels, or to help relieve emotional anxiety.
- Psychotherapy. The two approaches most often used in treating stress are interpersonal therapy and cognitive therapy. In interpersonal therapy, people learn about the events in their past and the triggers in their lives that set off the stress response, together with strategies for coping with stressors. Cognitive therapy works by teaching patients to change their ways of thinking about stressful situations or events. Many people have underlying negative assumptions about life that make them more vulnerable to stress.
- Lifestyle changes. People who have used alcohol, drugs, or smoking are usually advised to quit. In some cases, people may have to change jobs or leave bad relationships in order to relieve chronic stress.
- Physical exercise. Physical activity is a good way to work off tension in the muscles and joints, and to improve strength and endurance.
- Stress management. Stress management refers to programs or techniques intended to help people deal more effectively with stress. Many of these are intended to help people handle job- or work-place-related stress. Stress management programs ask participants to identify the specific aspects of their jobs that they find stressful and then plan a course of positive action to lower their stress levels.
- Complementary and alternative approaches. Acupuncture, yoga, relaxation training, meditation, prayer and religious practice, guided imagery, hypnosis, massage therapy, music therapy, humor, and pet therapy are alternative approaches that help many people cope with stress.
The prognosis for stress depends on the patients' overall health, their age, the specific stressors they confront, and the ways of coping that they have developed over time. Some people tend to focus on their feelings about the stressful situation while others focus on solving the problem. Still others react to stress by trying to escape from it through drugs or alcohol.
The National Institutes of Health (NIH) has compiled a list of ten things people can do to prevent stress:
- Stay away from stressors that can be avoided.
- Avoid making too many lifestyle changes too close together—such as trying to quit smoking while planning to move to a new city and take a new job.
- Recognize limitations and not take on too many responsibilities at the same time.
- Organize tasks according to priority and allow enough time to complete each one.
- Learn to communicate effectively and politely with others.
- Don't isolate; share thoughts or feelings with friends, family, or appropriate others, and take their advice if it seems reasonable and helpful.
- Create a positive attitude toward life.
- Set aside time for a break or a treat as a reward for overcoming a stressful situation.
- Get regular physical exercise, at least thirty minutes each day.
- Eat a healthy diet and get enough sleep.
The stress level in people's lives is likely to increase in the future rather than improve. One reason is the growing complexity and interconnectedness of the world; political, economic, and public health problems in almost any country can have an impact on others thousands of miles away. Another factor is the effect of the mass media and rapid communications. People are constantly bombarded with news about natural disasters and other frightening events.
SEE ALSO Depression; Eczema; Heart attack; Irritable bowel syndrome; Panic disorder; Posttraumatic stress disorder; Prematurity; Stroke
WORDS TO KNOW
Eustress: A term that is sometimes used to refer to positive stress.
Stress management: Any set of techniques intended to help people deal more effectively with stress in their lives by analyzing specific stressors and taking positive actions to minimize their effects.
Stressor: Any event or stimulus that provokes a stress response in a human or animal.
Hipp, Earl. Fighting Invisible Tigers: Stress Management for Teens. Minneapolis: Free Spirit Publishing, 2008.
Hyde, Margaret O., and Elizabeth H. Forsyth. Stress 101: An Overview for Teens. Minneapolis: Twenty-First Century Books, 2008.
Lawton, Sandra A., ed. Stress Information for Teens. Detroit: Omnigraphics, 2008.
American Academy of Family Physicians (AAFP). Stress: How to Cope Better with Life's Challenges. Available online at http://familydoctor.org/online/famdocen/home/common/mentalhealth/stress/167.html (updated December 2006; accessed September 29, 2008).
American Heart Association (AHA). How Can I Manage Stress? Available online in PDF format at http://www.americanheart.org/downloadable/heart/110167971464923%20HowCanIManageStress.pdf (updated December 2004; accessed September 29, 2008).
American Psychological Association Help Center. Stress: The Different Kinds of Stress. Available online at http://www.apahelpcenter.org/articles/article.php?id=21 (accessed September 29, 2008).
National Institute for Occupational Safety and Health (NIOSH). Working with Stress. Available online at http://www.cdc.gov/niosh/docs/video/stress1.html (produced in 2002; accessed September 29, 2008). This is a seventeen-minute video about job-related stress that can be downloaded as well as played online.
National Library of Medicine (NLM). Managing Stress. Available online at http://www.nlm.nih.gov/medlineplus/tutorials/managingstress/htm/index.htm (accessed September 29, 2008). This is an online tutorial with voiceover. Viewers have the option of a self-playing version, an interactive version with questions, or a text version.
TeensHealth. Stress. Available online at http://kidshealth.org/teen/your_mind/emotions/stress.html (updated July 2007; accessed September 29, 2008).