Understanding Stress

Stress is a physiological or emotional response to certain environmental events. The environmental events are called stressors. Examples of stressors include illness or death of a loved one, marital separation or divorce, losing a job, moving to a new residence, and many others as well. Any environmental event can be a potential stressor. Signs of becoming aware of stressors involve feeling conflicted, frustrated, and/or pressured. Stressors can cause physiological arousal which is an automatic response of the body to a danger, requiring a person to fight or to run away. This is called the fight or flight reaction. A particular stressor may or may not cause an individual to experience a stress response. This depends on the individual’s cognitive appraisal of the environmental event and the meaning that the event has for the individual. Stressors can be any major occurrence or life event that requires an individual to make an adjustment or adaptation to the event.

Cognitive appraisal of stressors is an essential part of the stress response system and consists of a two-part mental process which determines if an environmental event will be stressful. Primary appraisal is concerned with determining if an event is potentially harmful or threatening to an individual’s well being. Secondary appraisal is an evaluation of one’s ability to cope with events that are appraised to be harmful or threatening. Both primary and secondary appraisals are based mostly on an individual’s prior experiences and learning. Stress occurs when a person PERCEIVES that a stressor is threatening and believes that he or she is not able to cope effectively with the stressor.

Physiological arousal is an important manifestation of stress. Sympathetic stimulation of the Autonomic Nervous System promotes increased heart rate, blood pressure and respiration, along with decreased digestion during the experience of stress. The Endocrine System of glands, particularly the pituitary and adrenal glands, are also involved in the manifestation of stress. The catecholamines, norepinephrine and epinephrine (adrenalin), are closely involved in prolonging the sympathetic response and arousing the body for action. Corticosteroids such as cortisol increase metabolism, provide energy and decrease the immune system inflammatory response. These changes represent the emergency activating system of the body and reflect the “fight or flight” reaction of the body to perceived danger. Stress occurs in response to the perception of danger even when in fact there is no danger. Similarly, stress does not occur when there is no perception of danger even when in fact there is real danger. Perception, therefore, is the key to understanding how and why stress occurs in response to various stressors.

Perception itself is based on behavioral traits that develop throughout a person’s lifetime and are mostly learned. Traits such as pessimism or shyness, feelings of guilt or worry, and fears of rejection or failure can clearly influence how a particular person perceives a stressor. These behavioral traits may actually be very important indicators of how intensely environmental stressors are experienced. Therefore, they are sometimes referred to as internal stressors that interact with external, environmental stressors to cause stress. Regardless of how they are classified, behavioral traits influence how stressors are perceived and influence both the occurrence and the intensity of the stress response. Further discussion of the relationship between internal and external stressors will be the subject of a future blog post on the similarities and differences between stress, anxiety and fear.


Stress has been associated with the development of many illnesses, including heart disease, cancer and diabetes. The evidence to support this association is not conclusive, although there is some evidence that events perceived as stress are associated with increases in catecholamines and corticosteroids which correspond to changes in the immune system. Some people experience stress very intensely while others have relatively mild reactions. This is related to the degree of physiological arousal that occurs in different people. Most diseases are caused by many factors and stress should be considered as one of these potential causes.

Stress can affect illness directly through stress induced physiological changes. This is particularly the case with chronic stress, which occurs repeatedly in response to the same stressors. Stress can also affect illness indirectly by influencing individual health behaviors. People who experience high levels of stress are more likely to smoke, use alcohol, get into accidents, overeat, and engage in other behaviors that make illness more likely to occur. This often overlooked effect of stress on health behaviors may well be the basis for public health programs that seek to change destructive health habits. Individual health behaviors are intrinsic to the development of chronic diseases such as heart disease, stroke, diabetes and some cancers, Managing stressors effectively can, therefore, promote health and minimize illness.

From a public health perspective there are additional stressors that should be considered in understanding how large groups of people can experience stress, which can affect their health and well-being. Poverty is at the top of this list, and represents a formidable task for promoting health in this population. Poverty itself is a powerful stressor but it is also associated with additional stressors such as overcrowding, crime, noise, abuse, trauma and neglect. Various stress management techniques are available to reduce stress and improve health but they have to be tailored to particular individuals or groups.

In a separate blog post I will discuss the various mediators of stress that can increase or decrease the intensity of the stress response. In addition I will describe a variety of stress management techniques that have been developed, some of which are supported by good evidence for their efficacy in preventing or reducing stress.

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