Stress is an individual’s physical and mental reaction to environmental demands or pressures.

When stress was first studied, the term was used to denote both the causes and the experienced effects of these pressures. More recently, however, the word stressor has been used for the stimulus that provokes a stress response. One recurrent disagreement among researchers concerns the definition of stress in humans.

Is it primarily an external response that can be measured by changes in glandular secretions, skin reactions, and other physical functions, or is it an internal interpretation of, or reaction to, a stressor; or is it both?

Stress was first studied in 1896 by Walter B. Cannon (1871–1945). Cannon used an x-ray instrument called a fluoroscope to study the digestive system of dogs. He noticed that the digestive process stopped when the dogs were under stress.

Stress triggers adrenal hormones in the body and the hormones become unbalanced. Based on these findings, Cannon continued his experimentation and came up with the term homeostasis, a state of equilibrium in the body.

Hans Selye, a Canadian scientist (1907–1982), noticed that people who suffered from chronic illness or disease showed some of the same symptoms. Selye related this to stress and he began to test his hypothesis.

He exposed rats to different physical stress factors such as heat, sound, poison, and shock. The rats showed enlarged glands, shrunken thymus glands and lymph nodes, and gastric ulcers. Selye then developed the Three Stage Model of Stress Response.

This model consisted of alarm, resistance, and exhaustion. Selye also showed that stress is mediated by cortisol, a hormone that is released from the adrenal cortex. This increases the amount of glucose in the body while under stress.

Stress in humans results from interactions between persons and their environment that are perceived as straining or exceeding their adaptive capacities and threatening their well-being. The element of perception indicates that human stress responses reflect differences in personality, as well as differences in physical strength or general health.

Risk factors for stress-related illnesses are a mix of personal, interpersonal, and social variables. These factors include lack or loss of control over one’s physical environment, and lack or loss of social support networks.

People who are dependent on others (e.g., children or the elderly) or who are socially disadvantaged (because of race, gender, educational level, or similar factors) are at greater risk of developing stress-related illnesses. Other risk factors include feelings of helplessness, hopelessness, extreme fear or anger, and cynicism or distrust of others.

Causes and symptoms


The causes of stress can include any event or occurrence that a person considers a threat to his or her coping strategies or resources.

Researchers generally agree that a certain degree of stress is a normal part of a living organism’s response to the inevitable changes in its physical or social environment, and that positive as well as negative events can generate stress.

Stress related disease, however, results from excessive and prolonged demands on an organism’s coping resources. It is now believed that 80–90% of all disease is stress-related.

Recent research indicates that some vulnerability to stress is genetic. Scientists at the University of Wisconsin and King’s College, London, discovered that people who inherited a short, or stress-sensitive, version of the serotonin transporter gene were almost three times as likely to experience depression following a stressful event as people with the long version of the gene. Further research is likely to identify other genes that affect susceptibility to stress.


The symptoms of stress can be either physical and/or psychological. Stress-related physical illnesses, such as irritable bowel syndrome, heart attacks, and chronic headaches, result from long-term overstimulation of a part of the nervous system that regulates the heart rate, blood pressure, and digestive system.

Stress-related emotional illness results from inadequate or inappropriate responses to major changes in one’s life situation, such as marriage, completing one’s education, the death of a loved one, divorce, becoming a parent, losing a job, or retirement.

Psychiatrists sometimes use the term adjustment disorder to describe this type of illness. In the workplace, stress-related illness often takes the form of burnout—a loss of interest in or ability to perform one’s job due to long-term high stress levels.


When the doctor suspects that a patient’s illness is connected to stress, he or she will take a careful history that includes stressors in the patient’s life (family or employment problems, other illnesses, etc.). Many physicians will evaluate the patient’s personality as well, in order to assess his or her coping resources and emotional response patterns.

There are a number of personality inventories and psychological tests that doctors can use to help diagnose the amount of stress that the patient experiences and the coping strategies that he or she uses to deal with them.

Stress-related illness can be diagnosed by primary care doctors as well as by those who specialize in psychiatry. The doctor will need to distinguish between adjustment disorders and anxiety or mood disorders, and between psychiatric disorders and physical illnesses (e.g. thyroid activity) that have psychological side effects.


Relaxation training, yoga, t’ai chi, and dance therapy help patients relieve physical and mental symptoms of stress. Hydrotherapy, massage therapy, and aromatherapy are useful to some anxious patients because they can promote general relaxation of the nervous system.

Essential oils of lavender, chamomile, neroli, sweet marjoram, and ylang-ylang are commonly recommended by aromatherapists for stress relief.

Meditation can also be a useful tool for controlling stress. Guided imagery, in which an individual is taught to visualize a pleasing and calming mental image in order to counteract feelings of stress, is also helpful. Many individuals may find activities such as exercise, art, music, and writing useful in reducing stress and promoting relaxation.

Sometimes the best therapy for alleviating stress is a family member or friend who will listen. Talking about stressful situations and events can help an individual work through his or her problems and consequently reduce the level of stress related to them.

Having a social support network to turn to in times of trouble is critical to everyone’s mental and physical well-being. Pet therapy has also been reported to relieve stress.

Herbs known as adaptogens may also be prescribed by herbalists or holistic healthcare providers to alleviate stress. These herbs are thought to promote adaptability to stress, and include Siberian ginseng (Eleutherococcus senticosus), ginseng (Panax ginseng), wild yam (Dioscorea villosa), borage (Borago officinalis), licorice (Glycyrrhiza glabra), chamomile (Chamaemelum nobile), milk thistle (Silybum marianum), and nettle (Urtica dioica).

Practitioners of Ayurvedic, or traditional Indian, medicine might prescribe root of winter cherry, fruit of emblic myrobalan, or the traditional formulas geriforte or mentat to reduce stress and fix the imbalance in the vata dosha.

It is also said that stress reduces the body’s immune response, therefore vitamin supplementation can be helpful in counteracting the depletion. Diet is also important—coffee and other caffeinated beverages in high doses produce jitteriness, restlessness, anxiety, and insomnia.

High-protein foods from animal sources elevate brain levels of dopamine and norepinephrine, which are associated with higher levels of anxiety and stress. Whole grains promote production of the brain neurotransmitter serotonin for a greater sense of well-being.

Allopathic treatment

Recent advances in the understanding of the many complex connections between the human mind and body have produced a variety of mainstream approaches to stress-related illness.

Present treatment regimens may include one or more of the following:
  • Medications. These may include drugs to control blood pressure or other physical symptoms of stress as well as drugs that affect the patient’s mood (tranquilizers or antidepressants).
  • Stress management programs. These may be either individual or group treatments, and usually involve analysis of the stressors in the patient’s life. They often focus on job- or workplace-related stress. A number of studies have found that good stress management programs significantly reduce absenteeism from work and visits to the doctor. They also improve immune system function and overall well-being in patients with such chronic disorders as HIV infection and diabetes.
  • Behavioral approaches. These strategies include relaxation techniques, breathing exercises, and physical exercise programs including walking.
  • Biofeedback. Biofeedback is a technique in which patients are taught to interpret and respond to signals from their own bodies. It can be taught by doctors, dentists, nurses, and physical therapists as well as by psychologists or psychiatrists. Biofeedback is often recommended as a treatment for chronic tension-type headaches.
  • Massage. Therapeutic massage relieves stress by relaxing the large groups of muscles in the back, neck, arms, and legs. It is particularly helpful for people who tend to convert stress into muscle tension.
  • Cognitive therapy. These approaches teach patients to reframe or mentally reinterpret the stressors in their lives in order to modify the body’s physical reactions.

Expected results

The prognosis for recovery from a stress-related illness is related to a wide variety of factors in a person’s life, many of which are genetically determined (race, sex, illnesses that run in families) or beyond the individual’s control (economic trends, cultural stereotypes and prejudices).

It is possible, however, for humans to learn new responses to stress and change their experiences of it. A person’s ability to remain healthy in stressful situations is sometimes referred to as stress hardiness.

Stress-hardy people have a cluster of personality traits that strengthen their ability to cope. These traits include believing in the importance of what they are doing; believing that they have some power to influence their situation; and viewing life’s changes as positive opportunities rather than as threats.


Complete prevention of stress is neither possible nor desirable because stress is an important stimulus of human growth and creativity, as well as an inevitable part of life.

In addition, specific strategies for stress prevention vary widely from person to person, depending on the nature and number of the stressors in an individual’s life, and the amount of control he or she has over these factors.

In general, however, a combination of attitudinal and behavioral changes work well for most patients. The best form of prevention appears to be parental modeling of healthy attitudes and behaviors within the family.