This page is adapted from the module entitled "Dealing with Stress in Disasters" at the Local Public Health Institute of Massachusetts. (Link to the LPHI module)

What is Stress?

This page is copied from the Local Public Health Institute of Massachusetts module at the following link: Link to Building Psychological Resilience for Dealing with Disasters.

Merriam-Webster Dictionary defines stress as: "a physical, chemical, or emotional factor that causes bodily or mental tension, and may be a factor in disease causation." If you were to ask people to explain what stress is and how it affects them, you would likely get a wide variety of definitions. Many factors and situations have the potential to impact us in stressful ways, but it is important to note our individual perceptions and responses to these stimuli.

Athletes and performers often describe mental tension that arises prior to a contest or a performance, as anxiety or outright fear. Nevertheless, they acknowledge that this tension can both overwhelm the individual and result in a disastrous performance, or it can be the source of a positive response that brings out the very best in people. The graphic below attempts to illustrate both the potentially motivating effects of stress and the adverse effects of excessive or prolonged stress combined with poor coping skills (on the right).

Graphic showing how increassint stress improves performance up to a point, after which perfromance declines with increasing stress

Although we frequently have little control over stressful factors and situations, it is possible to train yourself to modulate your thoughts, emotions, and your environment in ways that help you to deal with the problems you encounter, rather than allowing events take control of you. Conceptually, your efforts to develop psychological resilience can expand your range of good stress and shrink the range of debilitating stress. This is what is meant by building psychological resilience, and it is particularly important for public health workers and emergency responders.

The Stress Reaction

French physiologist Claude Bernard was the first to introduce the concept of dynamic equilibrium, or steady state. Organisms, even individual cells within organisms, are subject to never-ending changes in conditions. But in order to survive and maintain optimal function, built-in mechanisms respond to altered conditions (stresses) by making adjustments that are designed to re-establish equilibrium. As a simple example, if the external temperature rises, our bodies automatically perspire - a compensatory response that reduces our internal temperature.

Neurologist Walter Cannon applied the term homeostasis to this concept of dynamic equilibrium. Cannon was the first to propose that stressors could be emotional as well as physical, and he described the "fight or flight" response that occurs when animals are threatened with immediate danger (a severe stress). Hans Selye, another scientist, extended Cannon's observation and discovered that the "fight or flight" response is mediated by the secretion of powerful neurotransmitters. Stimuli from the brain also cause the hypothalamus to release corticotrophin releasing factor (CRF). CRF then causes the secretion of adrenocorticophic hormone (ACTH) from the pituitary gland at the base of the skull. ACTH travels to the adrenal glands via the blood stream and stimulate the release of cortisol, epinephrine, and norepinephrine. These neural and hormonal mechanisms mediate our responses to both ordinary stresses and intense stress.



"Richard Davidson, a neuroscientist at the University of Wisconsin, Madison, thinks he's found a connection in the brain that is especially important for resilience: the path from the prefrontal cortex-the seat of cognition and planning-to the amygdala, an emotional part of the brain that responds to threats. A stronger connection means the prefrontal cortex can more quickly tell the emotional amygdala to quiet down...."

Excerpt from "Bounce Back" by Mandy Oaklander. TIme Magazine, Frontiers of Medicine, June 1, 2015


Types of Stress

One can also categorize stress based on its chronicity (from American Psychological Association: The Different Kinds of Stress). 

Chronicity of Stress