How Psychological Factors Influence Our Chances of Getting Sick


By Catherine A. SandersonAmherst College

To study how psychological factors influence people’s susceptibility to illness, researchers at Carnegie Mellon University conducted a series of studies starting in 1986 in which volunteers agreed to be exposed to the common cold virus, which was inserted into their nostrils. Researchers then examined these people every day for four weeks.

Man wrapped around a blanket and wiping his nose with a tissue
It turns out that people who are stressed are more likely to fall ill compared to people with relatively stress-free lives. (Image: Srdjan Randjelovic/Shutterstock)

As If Stress Wasn’t Bad Enough on Its Own

The researchers asked people whether they experienced any symptoms of the cold—runny nose, sore throat, coughing. They also took saliva samples to measure antibodies to the cold in their bodies. And, they even gathered and weighed the tissues used by the people during the cold. Thank you, scientists!

Across all of these measures, the researchers found consistent results: people who were under more stress at the start of the study were more likely to develop a cold. They didn’t have the ability to fight off the initial infection, whereas people who were not under stress could fight off that same infection.

Indirect Effects of Stress

But, stress also has indirect effects on health. Think about a time you’ve experienced a lot of stress and how it changed your regular behavior. During times of stress, most people stop engaging in behaviors that actually promote health, such as exercising. 

They may also start engaging in behaviors that hurt health—eating more high-fat and sugar foods, drinking alcohol, getting less sleep, and so on. These behaviors, in turn, weaken our body’s immune system and increase our likelihood of getting sick.

Psychological Factors

More recent findings have led to important updates to our model of stress. For example, the original fight-or-flight model was updated to include the possibility of a freeze response in the face of a threat—becoming immobile. 

Close up of half of the face of a man and a woman
According to a ground-breaking paper published in 2000, there are gender differences when it comes to responding to stress. (Image: ASDF_MEDIA/Shutterstock)

In addition, Shelley Taylor, a health psychologist at UCLA, published a ground-breaking paper in 2000 that shed light on another approach to managing stress: connecting with others. This model, tend-and-befriend, was based on a review of rodent, primate, and human studies showing that evolution led to gender differences in stress response.

Response to Stress Depends on Gender?

Taylor’s review noted that fleeing from stress would be less viable for a woman who is nursing or taking care of an infant. She also noted empirical research showing that during times of stress, women prefer to connect with other women, whereas men prefer to be alone. 

Biologically, stress triggers a release of oxytocin—the hormone associated with nurturing or love—and women’s higher estrogens levels are thought to enhance this release of oxytocin. Male hormones, such as testosterone, do not seem to enhance the social bonding effects of oxytocin.

This article comes directly from content in the video series Introduction to PsychologyWatch it now, on Wondrium.

Psychological Effects of Stress

In short, Selye’s model of stress, together with later updates, introduced the reality that stress causes a wide-ranging response across various body systems—the cardiovascular system, immune system, and so on. This view was in direct contrast to prior stimulus-response models that had all narrowly focused only on very specific responses of the body. His concept of stress made a huge contribution to the field of psychology.

However, Selye’s wide-ranging model of stress focused only on the physiological causes and effects of stress. It ignored the role of psychology and, as other researchers soon pointed out, psychological stressors and psychological stress responses are also important. And the scientific evidence is clear: stress can lead to serious and lasting psychological effects, including fear, anger, anxiety, sadness, and intense loneliness.

Following a trauma—such as an actual or threatened death, serious injury, or sexual assault—the psychological effects can be even more serious. Effects can include intrusive thoughts, difficulty sleeping, and feelings of numbness and dissociation. 

When these reactions occur immediately after the event, or at least within the first month, it is known as acute stress disorder. When the reactions linger longer than a month or first emerge more than a month after the event, the disorder is known as post-traumatic stress disorder, or PTSD.

The Nature of PTSD

Soldier sitting on a coach in front of a therapist
Those who have experienced extreme events may develop symptoms that continue for months, ending up in PTSD. (Image: Motortion Films/Shutterstock)

Although many people who experience an extreme event develop disruptive symptoms, these typically fade within days or weeks. But for people with PTSD, these symptoms continue for more than a single month and can become chronic, causing significant distress and difficulty in functioning in daily life. 

They can include severe anxiety, feeling on edge, bursts of anger, and constantly reliving the event through memories, flashbacks, and nightmares. Over time, these symptoms can also lead to serious health problems.

Those who live in close proximity to a traumatic event, or lose friends or loved ones, are especially vulnerable to PTSD. One study of people living in a town evacuated following the 2011 earthquake, tsunami, and nuclear power plant disaster in Japan found that more than half of the over 5,000 inhabitants showed some symptoms of PTSD.

Another study surveyed Virginia Tech students following a school shooting in which 49 faculty members and students were shot and 32 killed and found that about 15% of students continued to experience high levels of post-traumatic stress three to four months later, with PTSD especially likely for students who had someone close to them who was injured or killed.

Common Questions about How Psychological Factors Influence Our Chances of Getting Sick

Q: How does stress affect the immune system?

Research has shown that psychological factors can affect the immune system, factors such as stress. Stress not only undermines the immune system, it can lead to people letting go of healthy habits and attaching to unhealthy ones which indirectly also undermine one’s health.

Q: What are gender differences in response to stress?

Research has shown that evolution has led to gender differences in regard to one’s reaction to stress. Women usually connect with other women which helps elevate stress whereas men tend to be alone at such times.

Q: What is the difference between acute stress disorder and PTSD?

When we experience trauma or any sort of intense event that is tied to psychological factors and induces stress, the reactions that occur immediately or within the next month are known as acute stress disorder. However, if symptoms prolong for over a month, it’s known as post-traumatic stress disorder or PTSD.

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