Decades of research have demonstrated a clear link between stress levels, depression and immune system function. This section will quickly go over some of the key findings.
When using the word “stress” it might make sense to first define exactly what it means. Most research and the medical community basically define stress as “circumstances that most people find stressful.” An alternate definition is “when events or environmental demands exceed an individual’s perceived ability to cope” .
The issue is that this meaning is quite broad in nature. Clearly some individuals perceive a large amount of situations as stressful, while others, are extremely good at ignoring the situation and moving past the “stressful” event.
This difference in how individuals perceive stress has long puzzled researchers. In general, it appears to be influenced by genetics , an individual’s life experience , and maybe even nutrition .
Two General Types of Stress
In general, there are two main types of stress:
- Acute stress – brief circumstances which create stress (exams, threatening situations, etc.)
- Chronic stress – ongoing stress (marital problems, work related issues, financial stress, etc.)
The two types of stress are very different in nature and have equally different effects on health and immune function.
How Stress Impacts Immune Function
The central nervous system (brain), the endocrine system (glands responsible for the production of hormones) and the immune system interact with each other on a continuous basis. And the instability of just one system can have a negative impact on the whole body.
In the case of mental stress, the central nervous system can become over-worked. This event signals the endocrine system to kick-start the production of various hormones in an effort to aid the central nervous system.
Some of the most notable of these hormones include:
- Glucocorticoids (including cortisol) – involved in reduction of inflammation 
- Catecholamines (adrenaline and noradrenaline) – regulate immune activity 
- Growth hormone – stimulates T and B Cell production 
- Prolactin – impacts various cellular processes 
These hormones then circulate the body and have a direct influence on immune function. Yet it appears the influence they have actually depends on the type of stress.
In the case of acute stress immune function generally appears to be improved. This helps the body adequately cope with the situation by enhancing vital functions. .’
On the contrary, in the case of chronic stress an overall suppression of immunity has been demonstrated. This can create an optimal environment for illness and drastically impact the enjoyment one can obtain from life .
Put simply, short term stress can be beneficial, while chronic stress is highly debilitating.
Documented Effects of Stress on Immune Function
The overall consensus is as stress levels and duration increase, immune function declines. The amount of research in this area is quite immense.
Going over all the research findings is outside the scope of this book. Instead we will simply cover some of the most relevant and interesting findings.
Stress Alters Cytokine Production and Impacts Wound Healing
One of the more relevant findings (for someone with a chronic skin condition) is that stress can disrupt the production of inflammatory cytokines [12, 13]. And this is a crucial component of normal wound healing and an essential component of healthy skin.
The wound healing process occurs in a multi-step approach. Each step in the process is essential the overall success . But the first step is often considered as the most important.
This step includes significant innate immune activity to protect against infection and a coordinated recruitment of cells for the remodeling of damaged tissue . Issues at this stage of the process lead to significant delays and complications down the line.
Essentially, during times of stress the skin looses some of it’s ability to properly heal. And since chronic skin conditions can often be the source of chronic stress, a downward spiral may result.
Similarity Between Chronic Stress and Autoimmune Disease
Another important clue comes from the similarity between the effects chronic stress and AIDS on immune function. More specifically, during times of chronic stress T helper cell activity is drastically reduced  and a very similar effect on immune function can be observed in AIDS.
Now, if we consider the high rate of seborrheic dermatitis occurrence rates in AIDS patients, a possible connection appears. Perhaps, the negative impact of chronic stress may play a similar role (as AIDS) in seborrheic dermatitis occurrence and severity.
Managing stress in today’s world
Further discussion of stress and several strategies for eliminating chronic stress from our lives are provided later in the Stress section.
Additional Documented Effects of Stress
In addition to this, there is a considerable number of other documented effects that stress may have. This includes:
- Increase the risk of developing infectious disease [17, 18, 19]
- Increase the chance of developing poor health habits (smoking, bad food choices, drinking, drug abuse, etc.) [20, 21]
- Significantly weaken the cellular and humoral immune responses 
- Perpetuate the development of various inflammatory diseases (such as cardiovascular disease, osteoporosis, arthritis, and possibly even cancer) 
- Increase the rate of development of a herpes simplex virus infection and suppresses the immune responses response to the infection
- In HIV-infected men, levels of stress have been related to the rate of disease progression 
And this list is no where near complete. As a result, finding ways to minimize levels of stress in our lives is essential to adequate functioning of our bodies.
Find Suitable Coping Strategies May Prove Valuable
Regardless of what influences an individual’s susceptibility to stress, finding strategies to cope or remove stress may hold significant value in improving immune system function and potentially reversing atopic skin conditions such as seborrheic dermatitis [25, 26].
The significance of childhood stress
A study of 15,357 individuals clearly demonstrated that cumulative stress in childhood was a strong predictor for autoimmune diseases in adults .
This section outlined the complex relationship between stress, immune system function and potential connection to seborrheic dermatitis. Key points include:
- Identical situations can present different levels of stress and this depends on an individual’s tolerability for stress
- Acute stress and chronic stress can have very different impacts on immune function; while the first may be beneficial, the second is detrimental
- Chronic stress puts strain on the central nervous system and can result in unbalanced hormone production and unfavorable alterations in immunity
- Most relevant findings are in areas of cytokine (inflammation hormones) production, weakened immunity to infection and perpetuation of inflammatory disease
- The effects of chronic stress on immune function are similar to that of AIDS and a strong correlation between AIDS and seborrheic dermatitis exists
- Finding effective approaches to stress management may hold significant value for the management of various atopic and inflammatory conditions