sadness shown in picture Photograph courtesy of The Jed FoundationOpens in new window

People have an intuitive understanding of the concept of stress but may not be aware of all of its facets.

  • Stress is most commonly thought of as psychological tension (“I feel stressed”); this description is partly accurate.
  • Stress is also a physical response to a threatening or challenging situation (a stressor) and involves activation of most body systems.

This physical response, called the stress response or the fight-or-flight responseOpens in new window, is quite dramatic and includes:

  • elevated heart rate,
  • elevated blood pressure,
  • release of stress hormones including adrenaline,
  • mobilization of energy stores in the body (i.e., glucose in the liver),
  • a slowing of digestion,
  • enhanced blood flows to large muscles, pupil dilation, and many other physical changes.

In short, stress is experienced both physically and psychologically; it is an arousal of both body and mind.

The study of stress is popular largely because stress is costly to individuals. It can cause damage to the body that is severe enough to contribute to both physical and psychological disease states.

Both Sapolsky (2004) and McEwen and Lasley (2002) wrote highly informative and readable books about the relationship between stress and diseaseOpens in new window. As they (and others) describe, it is clear that stress contributes to heart disease. When under stress, the stress hormones cortisolOpens in new window and epinephrine (adrenaline)Opens in new window mobilize cholesterol and fats for energy.

The cholesterol and fats that are not used during the stress response may continue to circulate through the bloodstream, adhering to the inside of blood vessels. This adhesion, called atherosclerosisOpens in new window, reduces the circumference of the blood vessels, leading to an increase in blood pressure which can damage the entire circulatory system including the heart. This is only one of many ways that stress can contribute to heart disease.

Stress often suppresses the immune system, increasing susceptibility to many types of infection (possibly multiple infections).

As Sapolsky (2004) describes, the evidence is clearest regarding the common cold: immune suppression related to stress increases common cold risk. Additionally, stress is probably related to the worsening of AIDS. More research is needed to determine the precise relationships between stress, immune suppression, and susceptibility to infections of various kinds.

Stress contributes to psychiatric disease. A clear connection has been found between stress and clinical depression, which is more common among people who have experienced significant stress.

Research on the relationship between stress and psychiatric diseases including depression is currently active and promising.

Additionally, stress has been associated with symptoms that are not considered disorders, for example fatigue states (because the stress response is highly energy consuming) and irritability and interpersonal problems, both of which may be related to fatigue.

Even if stress does not cause a disease, it can affect an individual’s well-being. In sum, stress is related to many types of diseases, both physical and psychiatric, and general dysfunction.

A variety of stress management techniques are available to mitigate the damaging effects of stress, or even to prevent negative effects. As Monar, Lazarus, and Reevy (2007) describe, stress management techniques can be divided into three basic categories:

  1. A change in one’s environment or lifestyle, for example, maintaining proper nutrition, quitting smoking, or avoiding stressors.
  2. A change in one’s personality or perception, for example, choosing to see the silver lining in the cloud, using one’s sense of humor, or taking an anger managementOpens in new window course.
  3. A modification of the physiological effects of stress, for example, meditationOpens in new window, deep breathing, or massage.

A number of excellent books provide how-to descriptions of many potentially helpful stress management techniques, including Davis, Eshelman, and McKay’s (2008) The Relaxation and Stress Reduction WorkbookOpens in new window, which has sold over 700,000 copies.

As a number of stress experts, including Lazarus (1999), have noted, stress and emotion are interconnected: when one experiences an emotion, especially one of the negative emotions, a stress response ensues. (In general, strong emotions produce strong stress responses and mild emotions produce less intense stress responses.)

This is true regardless of the specific negative emotion—fear, anger, and sadness are all associated with increased heart rate, increased blood pressure, release of stress hormones, and so on. Lazarus therefore recommended that stress researchers and emotion researchers collaborate to better understand these psychological phenomena.

Stress Hormones

Several hormones play a key role in the complex mind-body reaction that is the stress response. Most stress hormones are secreted from the adrenal glands which are located above each kidney.

The stress response is initiated by a part of the brain called the hypothalamus. The hypothalamusOpens in new window, through both nerve connections and hormone-releasing factors that are released into the bloodstream, stimulates the pituitary gland, the master glandOpens in new window located immediately below the hypothalamus. In turn, the pituitary gland releases hormones into the bloodstream. These hormones stimulate the adrenal glands to release the hormones that more directly cause the stress response.

Two of the first hormones released by the adrenal glands, adrenaline (epinephrine) and noradrenalin (norepinephrine), primarily affect the cardiovascular system. Adrenaline increases the heart rate and the force of the heartbeat. Noradrenaline initiates contraction of blood vessels which increases blood pressure. With these actions, the heart becomes quite effective at delivering large quantities of blood, rapidly, to needed muscles and other parts of the body that are critically involved in the stress response. In addition, adrenaline increases muscle tension.

A few moments later, the adrenal glands release cortisol and aldosterone. Cortisol primarily mobilizes energy for the stress response. Specifically, it mobilizes fat stores, protein stores (using amino acides from muscle tissue), and increases blood glucose (sugar) through a metabolic process called gluconeogenesis. Aldosterone increases sodium retention, which causes water retention. The purpose of the increased water retention is to stimulate the elimination of body waste.

Many other hormones are involved in the stress response, including prolactin, endorphins, enkephalins, and vasopressin (an antidiuretic hormone). The stress response is dramatic and extremely complex.

Stress and stress hormones are associated with moods and emotions (Wallenstein, 2003). Cortisol has been linked with several emotions, including fear and depression. Adrenaline is linked with fear and anger. Much is still unknown about the precise relationships between stress hormones and emotion; a good starting point for investigating this topic is Gene Wallenstein’s (2003) book Mind, Stress, and Emotions: The New Science of Mood.

See Also:
  1. Davis, M., Eshelman, E.R., & McKay, M. (2008). The relaxation and stress reduction workbook (6th ed.). Oakland, CA: New Harbinger.
  2. McEwen, B., & Lasley, E.N. (2002). The end of stress as we know it. Washington, DC: Joseph Henry Press.
  3. Monat, A., Lazarus, R.S., & Reevy, G. (Eds.). (2007). The Praeger handbook on stress and coping. Westport, CT: Praeger.
  4. Sapolsky R.M. (2004). Why zebras don’t get ulcers. New York: Henry Holt.
  5. Lazarus, R.S. (1999). Stress and emotion: A new synthesis. New York: Springer.
  6. McEwen, B., & Lasley, E.N. (2002). The end of stress as we know it. Washington, DC: Joseph Henry Press.