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Stress, Health, Physiology, Mood, Behavior and the Fight-Flight Response
by Justin Lorenzo
Even everyday stressors can result in a variety of physiological reactions and behavioral responses.  Physical symptoms may present as minor aches and pains, trouble sleeping, chest tightness or muscle tension, shortness of breath, and other signs of increased arousal or anxiety.  In our desire to get through the day, we often ignore these minor symptoms.  We might cope by pretending that the symptoms don’t exist, having a drink to relax, or by taking over-the counter medicine to counteract the pain or help sleep. Increased stress and associated arousal can make us over-reactive and irritable.  Such feeling can result over-reaction and taking it out on those around us. 
As we move on with our busy lives, we may never truly reflect on the relationships between stress, our psychology, physiology, emotions, and actions.  These aspects are all much more closely related than one may initially think.
Acute stress has been linked to our mood, sense of well-being as well as physiological health.  For most healthy individuals, experiencing acute stress does not typically burden their health.  However, when the stressors are persistent, or seemingly never-ending, the risk of health impacts is greater.  This is particularly true for individuals who are older and may already be suffering from other health burdens. Chronically anxious individuals, Type-A personalities, and individuals with certain psychiatric or personality disorders can generate more stress for themselves and their environments, and be more vulnerable to acute and chronic stress effects.
The physical impacts of persisting stress include experiencing illness due to a lowered immune system, cardiac issues, as well as an increased risk of obesity and diabetes.  The link between stress and risk of cardiovascular disease is particularly well documented.  Notably, the World Heart Federation has found that experiencing acute stress causes reduced blood flow to the heart, as well as irregular heartbeat. These symptoms can then increase the risk for blood clotting and the development of cardiovascular disease.  For more information about cardiovascular disease and the impact of psychological risk factors, the following article is available on our website: Cardiovascular Disease, Mood Disturbance, and Cognitive Deficits. 
Psychological stressors surround us.  Everyday tasks, such as rushing to arrive to work on time, braking quickly to avoid a collision, flying, and speaking publicly, are all common stressors which may trigger a physiological response.  Our bodies control these responses through the autonomic nervous system (ANS), which is comprised of the parasympathetic and sympathetic nervous systems (PNS & SNS).  When we undergo stress, our SNS responds.  This response includes the release of adrenaline, the release of cortisol, and the acceleration of heart rate.  
During the sympathetic nervous system response, muscles tense, the trachea and bronchi dilate, and digestion is inhibited.  In an attempt to be ready for action in a high-stress situation, blood flow is directed to the skeletal muscles, the heart, and the brain instead of the skin and internal organs.  This response is commonly referred to as “fight or f light.”   
The fight-or-fight response is essentially an adaptive survival mechanism which allows us to better survive immediate threats, but when it is not relieved or there is continued exposure to random or chronic stressors, the constant tension can induce an overly active SNS and a chronic stress response. 
A number of changes occur in your body when you are feeling stressed.  One of the functions of the hypothalamus, the region of the brain that coordinates the ANS, is the regulation of a steady state, “homeostasis”, in the body by sending signals to the endocrine system, which is composed of a complex network of hormone-producing glands which govern metabolism, growth, development, sexual function, sleep, and more. 
In response to threat or other stressful stimuli or circumstances, the hypothalamus sends a signal to the pituitary gland which in turn sends a signal to the adrenal glands, which are located just above the kidneys.  Importantly, the signals tell the glands to secrete cortisol.  The cortisol hormone then attaches itself to receptors throughout the body which interact with other cells to perform their function. Cortisol is essential in regulating metabolism and immune responses.  In stressful situations, the increase of cortisol and adrenaline in the bloodstream elevates your heart rate and blood pressure, and increases your body’s energy stores.  This reaction is a good part of our survival fight-or-flight response and in most cases allows us to deal with threats or crises with increased strength, acuity, stamina and focus.  However, too much can interfere with cognitive flexibility, reasoning, and motor skills, can create tunnel vision, and can create an experience of pain or being overwhelmed.
The chart below illustrates the impact of increased short-term SNS heart rate changes, behavior and performance.
Beats Per Minute (BPM)
Normal Resting Heart Rate
Fine motor skills deteriorate
Optimal survival and combat performance level for:
·       Complex motor skills
·       Visual reaction time
·       Cognitive reaction time
·       Complex motor skills deteriorate
·       Cognitive processing deteriorates
·       Vasoconstriction (reduced bleeding from wounds)
·       Loss of peripheral vision (tunnel vision)
·       Loss of depth perception
·       Loss of near vision
·       Auditory exclusion
Above 175
(Copyright 1997 Siddle & Grossman)
·       Irrational fight or flee
·       Freezing
·       Submissive behavior
·       Voiding of bladder and bowels
·       Gross motor skills at highest performance level (running, charging, etc. at highest performance level)
Cortisol, a hormone, functions in conjunction with the SNS, and is responsible for converting liver glycogen into glucose for energy. Excessive cortisol production can occur when our SNS is overly active.  In addition to the heightened sense of urgency and call to action caused by the fight-or-flight response, physiological arousal can contribute to angry feelings, reactions, and behaviors. Over-arousal may lead to a number of symptoms including: elevation in blood pressure, increased heart rate, heart palpitations, dizziness, headaches, shortness of breath, and chest pain. Behaviorally, over-arousal may present itself as ceaseless worry, and irritability, and being short-tempered.  Over time, it can contribute to sleep difficulties, anxiety, and if not relieved, can contribute to depression, fatigue, and exhaustion.
The Parasympathetic Nervous System serves to reduce heart-rate, stimulates digestion, and increased blood flow to our internal organs.  The two systems, SNS and PNS, work in opposition to each other.  When a normal balance exists between both systems, symptoms are normally less prevalent. People can experience “PNS Backlash” once the immediate stress response is over.  Symptoms can include drops in energy levels, heart rate, and blood pressure. This can present as dizziness, nausea, vomiting, paleness, clammy skin, and/ or profound exhaustion. (Siddle & Grossman 1997).
Certain activities and therapies such as meditation, guided imagery, yoga, deep breathing, and muscle relaxation can serve to reduce SNS arousal.  Cognitive-behavioral therapies often employ combinations of good sleep hygiene, stress and time management strategies, attendance to good self-care through proper exercise and diet, and techniques to reduce physiological arousal, improve coping, and establish perspective. Developing anger management skills may also be needed for some individuals.
In some cases a combination of psychological and pharmacological approaches may be needed. In cases of significant depression, a combination of both is often more effective than either alone.  Antidepressants are often used as a non-addictive intervention for chronic anxiety but may require a number of weeks before a response occurs.  Some anxiety medications are addictive and may be best used only short-term. Non-addictive medications such as Propranol and similar beta-blockers can be effective for controlling the effects felt by anticipated stressors, such as a fear of flying or speaking and have been used to reduce development of PTSD symptoms immediately after traumatic events. 
With proper psychological care and attention to stressors, adverse physiological effects can be managed, likely without the need for additional medication. Addressing troublesome daily habits and reconsidering cognitive reasoning which may be causing anxiety could aid in the prevention of symptoms.   In most cases, psychological interventions for anxiety symptoms are successful in symptom relief or reduction, and allow for the discontinuation of medication used for insomnia and/ or anxiety.
References and Resources:

Anger Management


About the Author:  Justin Lorenzo, is a graduate of the University of Florida and served as an Office Intern with Clinical Psychology Associates of North Central Florida and planning to attend medical school.

Editors:  Jordan Shealy, Ernest J. Bordini, Ph.D.

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