In psychology, stress is a feeling of strain and pressure. Symptoms may include a sense of being overwhelmed, feelings of anxiety, overall irritability, insecurity, nervousness, social withdrawal, loss of appetite, depression, panic attacks, exhaustion, high or low blood pressure, skin eruptions or rashes, insomnia, lack of sexual desire (sexual dysfunction), migraine, gastrointestinal difficulties (constipation or diarrhea), and for women, menstrual symptoms. It may also cause more serious conditions such as heart problems. Also, experimental research which has been performed on animals, also displayed results relating to stress and negative effects on the body. It has been shown that stress contributes to the initiation and development of specific tumors within the body.
Small amounts of stress may be desired, beneficial, and even healthy. Positive stress helps improve athletic performance. It also plays factor in motivation, adaptation, and reaction to the environment. Excessive amounts of stress however, may lead to many problems in the body that could be harmful. Three diseases that are influenced by stress are clinical depression, cardiovascular disease, and human immunodeficiency virus (HIV).
Stress can be external and related to the environment, but may also be created by internal perceptions that cause an individual to have anxiety or other negative emotions surrounding a situation, such as pressure, discomfort, etc., which they then deem stressful, for example in PTSD.
External factors that by themselves are not threatening or stressful are deemed such for someone experiencing PTSD. Triggers can be stressful, such as when a person reports stress when hearing a song on the radio or seeing a type of object that may remind the person of prior threatening events. Humans experience stress, or perceive things as threatening, when they do not believe that their resources for coping with obstacles (stimuli, people, situations, etc.) are enough for what the circumstances demand. When we think the demands being placed on us exceed our ability to cope, we then perceive stress.
Coping mechanisms 
Individuals deal with perceived threats, that may be stressful, in various ways. There are different classifications for coping, or defense mechanisms, however they all are variations on the same general idea: There are good/productive and negative/counterproductive ways to handle stress. Because stress is perceived, the following mechanisms do not necessarily deal with the actual situation that is causing an individual stress. However, they may be considered coping mechanisms if they allow the individual to cope better with the negative feelings/anxiety that they are experiencing due to the perceived stressful situation, as opposed to actually fixing the concrete obstacle causing the stress. The following mechanisms are adapted from the DSM-IV Adaptive Functioning Scale, APA, 1994.
Highly adaptive/active/problem-focused mechanisms 
These skills are what one could call as “facing the problem head on”, or at least dealing with the negative emotions experienced by stress in a constructive manner. (generally adaptive)
• Humor – the individual steps outside of a situation in order to gain greater perspective, and also to highlight any comic aspect to be found in their stressful circumstances.
• Sublimation – allows an “indirect resolution of conflict with neither adverse consequences nor consequences marked by loss of pleasure. Essentially, this mechanism allows channeling of troubling emotions or impulses into an outlet that is socially acceptable.
• Positive reappraisal – redirects thoughts(cognitive energy) to good things that are either occurring or have not occurred. This can lead to personal growth, self-reflection, and awareness of the power/benefits of one's efforts.
Other adaptive coping mechanisms include anticipation, altruism, and self-observation.
Mental inhibition/disavowal mechanisms 
These mechanisms cause the individual to have a diminished (or in some cases non-existent) awareness about their anxiety, threatening ideas, fears, etc., that come from being conscious of the perceived threat.
• Repression – Repression occurs when an individual attempts to remove all their thoughts, feelings, and anything related to the upsetting/stressful (perceived) threat out of their awareness in order to be disconnected from the entire situation. When done long enough in a successful way, this is more than just denial.
• Reaction formation – An individual substitutes their feelings or thoughts or behavior with the exact opposite. An attempt to remove any “unacceptable thoughts” from one's consciousness by replacing them with the exact opposite.
Other inhibition coping mechanisms include undoing, dissociation, denial, projection, and rationalization. Although some people claim that inhibition coping mechanisms may eventually increase the stress level because the problem is not solved, but detaching from the stressor can sometimes help people to temporarily release the stress and become more prepared to deal with problems later on.
Active mechanisms 
These methods deal with stress by an individual literally taking action, or withdrawing.
• Acting out – Often viewed as counter-normative, or problematic behavior. Instead of reflecting or problem-solving, an individual takes maladaptive action.
• Passive aggression – When an individual indirectly deals with his or her anxiety and negative thoughts/feelings stemming from their stress by acting in a hostile or resentful manner towards others. Help-Rejecting Complaining can also be included in this category.
Depending on the situation, all of these coping mechanisms may be adaptive, or maladaptive.
Stress responses 
In terms of measuring the body's response to stress, psychologists tend to use Han Selye's general adaptation syndrome. This model is also often referred to as the classic stress response, and it revolves around the concept of homeostasis. According to the concept of homeostasis, in response to stressors the body seeks to return to its equilibrium state, or the normal level of stress resistance. During the alarm phase, the body begins to build up resistance to the stressor beyond normal resistance levels.
During this phase the body mobilizes the sympathetic nervous system to meet the immediate threat. The individual's body reacts by releasing adrenal hormones that produces a boost in energy, tense muscles, reduced sensitivity to pain, the shutting down of digestion, and a rise in blood pressure. In the resistance phase the individual's body attempts to resist or cope with a persistent stressor that cannot be avoided. The physiological responses of the alarm phase continue and make the body much more vulnerable to other stressors.
The body continues building up resistance throughout the stage of resistance, until either the body's resources are depleted, leading to the exhaustion phase, or the stressful stimulus is removed. This three phase response is designed to help humans in life or death situations, but all types of stressors can trigger this response. A stress response results in elevated physiological arousal, often associated with the release of stress hormones such as cortisol. The physiological arousal in response to stressors is designed to help the body adapt quickly in order to survive and rid itself of the stressful stimuli.
This physiological stress response involves high levels of sympathetic nervous system activation, often referred to as the "fight or flight" response. The response involves pupil dilation, release of endorphins, increased heart and respiration rates, cessation of digestive processes, secretion of adrenaline, arteriole dilation, and constriction of veins. This high level of arousal is often unnecessary to adequately cope with micro-stressors and daily hassles; yet, this is the response pattern seen in humans, which often leads to health issues commonly associated with high levels of stress.
Psychological stress and disease 
Negative affective states, such as feelings of anxiety and depression, could influence the pathogenesis of physical disease, which in turn, have direct effects on biological process that could result in increased risk of disease in the end. For example, when humans are under chronic stress, permanent changes in their physiological, emotional, and behavioral responses are most likely to occur. Such changes could lead to disease. Chronic stress results from stressful events that persist over a relatively long period of time, such as caring for a spouse with dementia, or results from brief focal events that continue to be experienced as overwhelming long after they are over, such as experiencing a sexual assault.
Experiments show that when healthy human individuals are exposed to acute laboratory stressors, they show an adaptive enhancement of some markers of natural immunity but a general suppression of functions of specific immunity. By comparison, when healthy human individuals are exposed to real-life chronic stress, this stress is associated with a biphasic immune response where partial suppression of cellular and humoral function coincides with low-grade, nonspecific inflammation.
Even though psychological stress is often connected with illness or disease, most healthy individuals can still remain disease-free after confronting chronic stressful events. This suggests that there are individual differences in vulnerability to the potential pathogenic effects of stress; individual differences in vulnerability arise due to both genetic and psychological factors.
Stress and health 
There is likely a connection between stress and illness. Theories of the stress–illness link suggest that both acute and chronic stress can cause illness, and there are several studies that have found such a link. According to these theories, both kinds of stress can lead to changes in behavior and in physiology. Behavioral changes can be smoking, alcohol consumption, eating and exercise, and physiological changes can be changes in sympathetic activation or hypothalamic pituitary adrenocorticoid activation. However, there is much variability in the link between stress and illness.
Stress makes the individual more susceptible to physical illnesses like the cold or flu. Stressful events, such as job changes, often result in insomnia, impaired sleeping, and health complaints.
Chronic stress and a lack of coping resources available or used by an individual can often lead to the development of psychological issues such as depression and anxiety (see below for further information). This is particularly true regarding daily stressors. These types of stressors tend to have a more negative impact on health because they occur daily and thus require the body's physiological response to occur daily. This depletes the body's energy more quickly and usually occurs over long periods of time, especially when these microstressors cannot be avoided (i.e.- traffic on the way to work). Studies have also proven that perceived chronic stress and the hostility associated with Type A personalities are often associated with much higher risks of cardiovascular disease. This occurs because of the compromised immune system as well as the high levels of arousal in the sympathetic nervous system that occur as part of the body's physiological response to stressful events.
However, it is possible for individuals to exhibit hardiness—a term referring to the ability to be both chronically stressed and healthy. Many psychologists are currently interested in studying the factors that allow hardy individuals to cope with stress and evade most health and illness problems associated with high levels of stress. Stress can be associated with psychological disorders such as general anxiety disorder, depression, and post-traumatic stress disorder. However, it is important to note that everyone experiences some level of stress, and diagnosis of stress disorders can only be performed by a licenced practitioner.
In animals, stress contributes to the initiation, growth, and metastasis of select tumors, but studies that try to link stress and cancer incidence in humans have had mixed results. This can be due to practical difficulties in designing and implementing adequate studies.
Stress management 
Stress management refers to a wide spectrum of techniques and psychotherapies aimed at controlling a person's levels of stress, especially chronic stress, usually for the purpose of improving everyday functioning.
Stress prevention & resilience building 
Although many techniques have traditionally been developed to deal with the consequences of stress considerable research has also been conducted on the prevention of stress, a subject closely related to psychological resilience-building. A number of self-help approaches to stress-prevention and resilience-building have been developed, drawing mainly on the theory and practice of cognitive-behavioural therapy.
Biofeedback may also play a role in stress management. A randomized study by Sutarto et al. assessed the effect of resonant breathing biofeedback (recognize and control involuntary heart rate variability) among manufacturing operators; depression, anxiety and stress significantly decreased.[non-primary source needed]
Types of stressors 
A stressor is any event, experience, or environmental stimulus that causes stress in an individual. These events or experiences are perceived as threats or challenges to the individual and can be either physical or psychological. Researchers have found that stressors can make individuals more prone to both physical and psychological problems, including heart disease and anxiety.
Stressors are more likely to affect an individual's health when they are "chronic, highly disruptive, or perceived as uncontrollable". In psychology, researchers generally classify the different types of stressors into four categories: 1) crises/catastrophes, 2) major life events, 3) daily hassles/microstressors, and 4) ambient stressors.
This type of stressor is unforeseen and unpredictable and, as such, is completely out of the control of the individual. Examples of crises and catastrophes include: devastating natural disasters, such as major floods or earthquakes, wars, etc. Though rare in occurrence, this type of stressor typically causes a great deal of stress in a person's life. A study conducted by Stanford University found that after natural disasters, those affected experienced a significant increase in stress level.
Major life events 
Common examples of major life events include: marriage, going to college, death of a loved one, birth of a child, etc. These events can be either positive or negative. Research has found major life events are somewhat rare to be major causes of stress, due to its rare occurrences.
The length of time since occurrence and whether or not it is a positive or negative event are factors in whether or not it causes stress and how much stress it causes. Researchers have found that events that have occurred within the past month generally are not linked to stress or illness, while chronic events that occurred more than several months ago are linked to stress and illness. Additionally, positive life events are typically not linked to stress—and if so, generally only trivial stress—while negative life events can be linked to stress and the health problems that accompany it.
Daily hassles/microstressors 
This category is the most commonly occurring type of stressor in an individual's everyday life. This includes daily annoyances and minor hassles. Examples include: making decisions, meeting deadlines at work or school, traffic jams, encounters with irritating personalities, etc. Often, this type of stressor includes conflicts with other people. Daily stressors, however, are different for each individual, as not everyone perceives a certain event as stressful. For example, most people find public speaking to be stressful, nevertheless, a seasoned politician most likely will not. Travel-related stress results from three main categories, according to a global stress survey conducted by Carlson Wagonlit Travel: lost time, surprises (an unforeseen event such as lost or delayed baggage) and routine breakers (inability to maintain daily habits).
There are three major psychological types of conflicts that can cause stress. First, the approach-approach conflict occurs when a person is choosing between two equally attractive options, i.e. whether to go see a movie or to go see a concert. The second type is the avoidance-avoidance conflict, where a person has to choose between two equally unattractive options, for example, to take out a second loan with unappealing terms to pay off the mortgage or to face foreclosure on one's house.
The third type is an approach-avoidance conflict. This occurs when a person is forced to choose whether or not to partake in something that has both attractive and unattractive traits—such as whether or not to attend an expensive college (meaning taking out loans now, but also meaning a quality education and employment after graduation).
Ambient stressors 
As their name implies, these are global (as opposed to individual) low-grade stressors that are a part of the background environment. They are defined as stressors that are "chronic, negatively valued, non-urgent, physically perceptible, and intractable to the efforts of individuals to change them". Typical examples of ambient stressors are pollution, noise, crowding, and traffic. Unlike the other three types of stressor, ambient stressors can (but do not necessarily have to) negatively impact stress without conscious awareness. They are thus low on what Stokols called "perceptual salience".
Stress scales 
Stress scales are lists of life events that can contribute to illness in an individual. The most common scale is the Holmes and Rahe Stress Scale, also known as the Social Readjustment Rating Scale, or SRRS. Developed by psychiatrists Thomas Holmes and Richard Rahe in 1967, the scale lists 43 events that can cause stress.
To calculate one's score, add up the number of "life change units" if an event occurred in the past year. A score of more than 300 means that individual is at risk for illness, a score between 150 and 299 means risk of illness is moderate, and a score under 150 means that individual only has a slight risk of illness.
|Life event||Life change units|
|Death of a spouse||100|
|Death of a close family member||63|
|Personal injury or illness||53|
|Dismissal from work||47|
|Change in health of family member||44|
|Gain a new family member||39|
|Change in financial state||38|
|Death of a close friend||37|
|Change to different line of work||36|
|Change in frequency of arguments||35|
|Foreclosure of mortgage or loan||30|
|Change in responsibilities at work||29|
|Child leaving home||29|
|Trouble with in-laws||29|
|Outstanding personal achievement||28|
|Spouse starts or stops work||26|
|Begin or end school||26|
|Change in living conditions||25|
|Revision of personal habits||24|
|Trouble with boss||23|
|Change in working hours or conditions||20|
|Change in residence||20|
|Change in schools||20|
|Change in recreation||19|
|Change in church activities||19|
|Change in social activities||18|
|Minor mortgage or loan||17|
|Change in sleeping habits||16|
|Change in number of family reunions||15|
|Change in eating habits||14|
|Minor violation of law||10|
A modified version was made for non-adults. The scale is below.
|Life Event||Life Change Units|
|Death of parent||100|
|Divorce of parents||90|
|Acquiring a visible deformity||80|
|Fathering an unwed pregnancy||70|
|Jail sentence of parent for over one year||70|
|Marital separation of parents||69|
|Death of a brother or sister||68|
|Change in acceptance by peers||67|
|Pregnancy of unwed sister||64|
|Discovery of being an adopted child||63|
|Marriage of parent to stepparent||63|
|Death of a close friend||63|
|Having a visible congenital deformity||62|
|Serious illness requiring hospitalization||58|
|Failure of a grade in school||56|
|Not making an extracurricular activity||55|
|Hospitalization of a parent||55|
|Jail sentence of parent for over 30 days||53|
|Breaking up with boyfriend or girlfriend||53|
|Beginning to date||51|
|Suspension from school||50|
|Becoming involved with drugs or alcohol||50|
|Birth of a brother or sister||50|
|Increase in arguments between parents||47|
|Loss of job by parent||46|
|Outstanding personal achievement||46|
|Change in parent's financial status||45|
|Accepted at college of choice||43|
|Being a senior in high school||42|
|Hospitalization of a sibling||41|
|Increased absence of parent from home||38|
|Brother or sister leaving home||37|
|Addition of third adult to family||34|
|Becoming a full fledged member of a church||31|
|Decrease in arguments between parents||27|
|Decrease in arguments with parents||26|
|Mother or father beginning work||26|
Some common misconceptions about stress 
Stress, as a definition, is often used incorrectly. Stressors are events, situations, stimuli, etc. that can cause people to perceive threat, thus they experience anxiety, overwhelmed-ness, or other negative emotions. In fact it is not these events, these traumas, conversations, etc. that "stress" us out, but instead our perception of how we will be able to cope with these stimuli. (See definition of stress at top)
Physiologically, day to day/chronic stressors have a greater negative impact on individuals' health than do more acute, traumatic stressors that generally have a start and an end point (see classic stress response, above). For example, daily stressors like dealing with traffic, finishing homework assignments, etc., cause more harm on one's health in the long run than do stressors such as a death in the family, marriage, etc. (see "types of stressors" above; crisis/catastrophes v. major life events/macro stressors v. daily hassles/micro stressors.
See also 
- Posttraumatic stress disorder
- Complex post-traumatic stress disorder
- Psychological trauma
- Cognitive behavioral therapy
- Acute stress reaction
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