What is stress?

Put simply, stress is the body’s emotional and physical response to a change. The change can be anything from the birth of a baby or scoring a touchdown to traffic jams, financial pressures, divorce, or illness. One of the ways your body responds to stress is by shifting energy from your immune system and the digestive system to the heart -- increasing heart rate and blood pressure. This is fine for short periods of time, but if these changes are frequent or prolonged -- as in chronic stress -- they can take a toll on your body. Chronic stress without periods of relaxation or relief can deplete your energy, cause relationship problems, and lead to smoking, drinking, overeating, and other negative behaviors. Chronic stress can also lead to depression.
Darren Treasure, PhD
Sports Medicine

Stress is a normal physiological and psychological response to events that cause a person to feel physically or emotionally threatened. When a person senses threat – real or imagined – the body reacts with a rapid, automatic process known as the stress response or “fight-or-flight. ”  The stress response is the body’s way of protecting you that, when working, helps you stay focused, energetic, and alert. In emergency situations, this stress response can save your life while it can also help you rise to meet challenges in your everyday existence. Beyond a certain point, however, stress stops being helpful and starts causing major damage to your health, your mood, your productivity, your relationships, and your overall quality of life. People who experience high levels of chronic stress often engage in excessive worry, poor decision making, procrastination and nervous habits such as nail biting. They often drink too much, eat too much or too little, and experience sleep problems and pain. The key is for everyone to understand their personal threshold when stress stops being helpful and becomes a negative. 

William B. Salt II., MD
Emeran A. Mayer, a gastroenterologist and Director of the University of California, Los Angeles (UCLA) Mind Body Collaborative Research Center, says that "Stress, defined as acute threats to the homeostasis of an organism, be they real (physical) or perceived (psychological), and whether posed by events in the outside world or from within, evokes adaptive responses which serve to defend the stability of the internal environment and to assure the survival of the organism." A stressor can be external, internal or both external and internal.
Irritable Bowel Syndrome & the MindBodySpirit Connection: 7 Steps for Living a Healthy Life with a Functional Bowel Disorder, Crohn's Disease, or Colitis (Mind-Body-Spirit Connection Series.)

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Dr. Michael Roizen, MD
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Stress is more than just the feeling that there's too much to do, too little time to do it, and too many hassles along the way. Stress is a very complex set of physiologic and psychological reactions. Dr. Hans Selye, one of the earliest researchers to study stress, defined it as "the nonspecific response of the body to any demand made on it." Simply put, stress is the body's reaction when it anticipates the need for extra energy. Almost anything can provoke this reaction: an injury, working under a deadline for a crazy boss, not sleeping enough, or not eating regular meals.
The RealAge Makeover: Take Years off Your Looks and Add Them to Your Life

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Why not live at 60 feeling like you did at 35?Thousands of Americans are younger today than they were five years ago. How is that possible? By following the specific recommendations that reverse...
Stress is a psychological and physical response by your body to anything that is perceived as a threat or a challenge. Stress can be caused by either a negative challenge (like a death in the family) or a positive challenge (such as a wedding).
Stress serves a necessary function in life. When you experience stress, your body acts like an alarm system. It makes hormones (such as adrenaline and cortisol) that give you a burst of extra energy. This helps you get through temporary periods of stress until you can relax again. 
However, chronic stress, or feeling “stressed out,” is thought to contribute to health problems like heart disease. It can also make you less likely to maintain healthy lifestyle behaviors, such as eating a nutritious diet and exercising.

When the demands placed on us exceed our perceived ability to cope, we experience stress. Stress is also defined as the thoughts, feelings, behaviors, and physiological changes that happen as a result of our response to those demands and perceptions. A whopping 82 percent of women say they have had at least one physical stress symptom in the last month such as a relentless headache, an upset stomach, or tightness in the chest.

From The Mind-Beauty Connection: 9 Days to Less Stress, Gorgeous Skin, and a Whole New You by Amy Wechsler.

Kelly Traver
Internal Medicine

Stress is the physiologic response to an event. It is not the event itself.

This is an important concept to understand because although you may not be able to prevent external stress-producing events from happening, you can learn to control your response to those events. You can influence the way thought patterns work in your brain, and you can learn to use this fact to your advantage in a big way.

Stress can be defined as a state or condition caused by the body's automatic response to a perceived or real threat. While the thoughts and realities that trigger stress are processed in our minds, stress ultimately affects the whole body in a physical way.

Our Bodies, Ourselves: Menopause

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There are two kinds of stress, distress and eustress. Distress is the kind that results in deterioration of your system. Eustress is the kind that supports your life force energy and helps you feel alive and productive.

You need to quickly reduce your Distress so you can enhance your life by releasing the Eustress or energy that supports your passion and goals.

Stanford Medical School and the World Health Organization agree that stress causes 85-95% of all illness and disease. What is stress? On a primitive level, you have protective fight, flight and freeze responses that effectively help you to deal with immediate or perceived threats to survival. When you engage these responses for long periods without rest, the body deteriorates. Chronic stress shuts down the immune system, resulting in chronic illness.

Being on "red alert" for long periods in this high-pressure culture is the norm for most people. So are fatigue, irritability, autoimmune syndromes like fibromyalgia and chronic fatigue, addictions, obesity and chronic disease.
Alice Domar
We’d like to propose a tidy definition that pinpoints both a cause and solution: Stress is the fear that you don’t have the resources to successfully meet your challenges.

Interesting, isn’t it? According to this definition, stress is not caused by the challenges themselves. It’s caused by a perceived shortage of resources -- not enough time, not enough money, not enough talent, not enough emotional support. For example, my co-author and I take on a lot of work each year: writing books, giving talks, traveling, in addition to our jobs, homes, and families. It’s a good life, but it comes with the fear that we won’t have time to get everything done, or that we will have to make unacceptable personal sacrifices to meet our obligations. That’s a major source of stress for us. Note that the stress is not caused by our workload itself but by our reactions to it. (“How will I get it all done?” or “What if my plane is late and I have to miss my daughter’s school dance?”)
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Patricia A. Bloom, MD
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A “stressor” is a stimulus that causes a reaction, so we usually refer to a stressor or stressors as “stress”. Our body’s instinctual response to a severe acute stress can be life-saving, as when one is able to jump out of the way of an oncoming car. And some amount of stress can be motivating or challenging, resulting in achievement. So we might think of some stress as good; it energizes us, allows us to be creative and solve problems, and historically has been crucial in preserving our species. However, exposure to chronic stress, even low levels over a period of time, has the potential to be damaging. Whether or not it is depends on a multitude of factors, including genetics, life experiences, health-related behaviors, and importantly, how we perceive the stress.

Stress, as defined from an online medical dictionary, is "an organism's total response to environmental demands or pressures." There is disagreement about how to define this in humans, however. The question is, is stress something that can be evaluated by looking at a physical response (e.g., blood pressure, skin reactions, etc.), or is it an internal/emotion driven reaction to a stressor, or some combination of both.      

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.