Stress and the Immune System
Stress and the Immune System
Joy Stepinski, MSN, RN-BC
September 7, 2025
In a previous article, we reviewed the fourth assumption in Less Medicine More Health by Dr. H. Gilbert Welch [1]. This assumption delved into a discussion that getting more information may not always be the best choice for some people. One reason is that an overabundance of information can lead to greater fear and anxiety. Fear can cause a release of cortisol in the body, which can affect health in itself.
The body always seeks balance, or homeostasis. Cortisol is needed in just the right amount. The hormone is synthesized by the adrenal glands, which are small glands that sit on top of both kidneys. An area of the brain called the hypothalamus initiates a series of steps that ultimately causes the release of cortisol by the adrenal glands. The circadian rhythm governs cortisol, which peaks in the morning to provide alertness and decreases in the evening to promote rest [2]. As a result, a person feels energized, has good cognitive function, and can manage stress effectively.
Cortisol regulates metabolism, the sleep-wake cycle, immune function, and blood sugar. The hormone regulates blood pressure and the ability of blood vessels to constrict [3]. When the body is in “fight or flight” mode, cortisol increases cardiac output to improve blood supply to vital organs and respond to threats. However, excessive cortisol can have adverse effects on the body. Chronic stress or other disease states can disrupt the circadian rhythm, causing sustained inflammation. Consequently, a person may experience sleep disturbances, high blood pressure, cognitive changes, suppressed immune function, and more vulnerability to infections.
Showing that stress plays a role in infections [4], the authors of one study investigated physiological stress and susceptibility to the common cold. They enrolled 394 subjects and administered nasal drops with one of five live respiratory viruses. Saline nasal drops were given to another 26 participants. The results showed that respiratory infections increased with the degree of psychological stress the subjects experienced. The study concluded that stress likely caused suppression of immune processes within the body and resistance to infection.
In her book Radical Remission, Kelly Turner discusses not holding onto any emotion for too long. Turner researched events leading to radical remission, when those diagnosed with serious cancers have survived against the odds. She uses the analogy that emotions should flow through the body, much like waves crashing on the beach [5]. For example, if a person chronically internalizes fear, the body can hold onto this emotion, which can consequently lead to physical disease. Such examples include autoimmune disease, heart disease, and cancer. The mind and the body are not separate from one another. Emotions affect every single cell in the body,
Turner discusses that stress management can help the body release these emotions. She suggests action steps, like journaling, practicing daily forgiveness, pursuing a stress management class, seeking a therapist, or trying Eye Movement Desensitization and Reprocessing (EMDR) therapy. She writes, “The goal is not to force ourselves to feel 100 percent happy all the time, but rather to let all types of emotions – whether positive or negative – flow in, through, and out of us, so that nothing from the past is carried over into the present, and each moment can be an opportunity for a new emotional experience” (p. 163).
When faced with a diagnosis and overwhelming information, people tend to feel fear. The body senses this heightened threat, causing the release of cortisol. Although cortisol normally maintains homeostasis and to protect the body, the body enters into overdrive. Excess cortisol leads to persistent inflammation, weakened immune defenses, and impaired ability to heal. This knowledge should always be considered when making a medical decision. Turner has some important stress management techniques. Yet, returning to Welch’s recommendations from last month, consider the following:
1. What are we looking for?
2. What will we do differently if we find what we’re looking for?
3. Is the information valuable?
4. What happens if the results are unexpected?
These considerations allow for informed decision-making where you can be more in control of your own health.
References
Welch, H. G. (2015). Less medicine, more health: 7 assumptions that drive too much medical care. Beacon Press.
Andreadi, A., Andreadi, S., Todaro, F., Ippoliti, L., Bellia, A., Magrini, A., ... & Lauro, D. (2025). Modified Cortisol Circadian Rhythm: The Hidden Toll of Night-Shift Work. International Journal of Molecular Sciences, 26(5), 2090.
Knezevic, E., Nenic, K., Milanovic, V., & Knezevic, N. N. (2023). The role of cortisol in chronic stress, neurodegenerative diseases, and psychological disorders. Cells, 12(23), 2726.
Cohen, S., Tyrrell, D. A., & Smith, A. P. (1991). Psychological stress and susceptibility to the common cold. New England Journal of Medicine, 325(9), 606-612.
Turner, K. A. (2014). Radical remission: Surviving cancer against all odds. Harper Collins.