Why does stress make us sick more easily?

Why does stress make us sick more easily?

Most diseases that we are dealing with nowadays are chronic diseases as a result of poor lifestyle choices that will only affect us later in life. However, we can get sick much sooner when exposed to chronic stress. How can this happen?

Stress is defined as a series of events, starting with a stimulus leading to a stress response known as the 'fight-or-flight' reaction that can affect many body systems.
Physical or physiological stress is mostly short-lived, while psychological or emotional stress can last for a very long time.

Stress and the immune system

The immune system is a complex system working together as the body’s defense mechanism to protect us from illness. Short-term acute stress may be beneficial for our immune health, as it stimulates immune activity and prepares us for possible periods of longer stress. But chronic stress is harmful for our health.

White blood cells (WBC) are critical for the body’s immune response to foreign invaders. These cells are produced, and stored, in many areas of the body including the spleen, bone marrow, and thymus (a gland found behind the sternum).
There are two types of WBCs associated with the immune system: phagocytes, which actively attack foreign organisms, and lymphocytes, which remind the body to recognize previous invaders and help destroy them.

The main phagocyte is the neutrophil. Neutrophils primarily fight bacteria and infections.
The main lymphocytes are the B lymphocytes or B-cells and T lymphocytes or T-cells.
B-cells start out and mature in the bone marrow.
T-cells start out in the bone marrow but mature in the thymus. These two cell types are the 'special forces' of the immune system and have specific functions.
B-cells make antibodies to fight bacteria and viruses and T-cells directly attack invading organisms.

Acute stress and the immune response

One of the most familiar reactions to acute stress is the 'fight-or-flight' reaction.
This physiological reaction usually occurs during an emergency or a fearful mental or physical situation.
When a threat is perceived, there is a release of hormones to prepare you to either stay and deal with the threat or to run away to safety. It represents choices our ancient ancestors made when faced with dangerous situations.
Nowadays, it’s more likely those dangerous situations are ones leading to a wound or infection, but our body reacts the same way. During periods of short-term stress, our sympathetic nervous system releases 'stress' hormones: epinephrine (adrenaline) and norepinephrine (noradrenaline), as well as corticotropin-releasing hormone (CRH), adrenocorticotropin (ACTH), and cortisol from the adrenal glands.

These work together to prepare the body for 'fight-or-flight' by increasing alertness, focusing the mind, elevating heart and breathing rates, as well as increasing blood flow to skeletal muscles and brain.

Acute stress activates the immune system. Immune activation is critical to respond to immediate demands of a stressful situation that may lead to a wound or an infection. Acute stress triggers immune cells and stimulates production of cytokines.
The two major types of cytokines are: pro-inflammatory cytokines and anti-inflammatory cytokines.
The pro-inflammatory cytokines process the pain often found with inflammation.
The anti-inflammatory cytokines work by controlling, or limiting, the spread of inflammation. Both are necessary for normal healing.

While acute short-term stress acts as an immune stimulator, readying the body’s immune system for an adverse situation, situations involving chronic long-term stress actually suppress the body’s immune system, leading to illness and poor health.

Chronic stress and the immune response

Sometimes there's a crossover between the mind and body, as in the 'fight-or-flight' reaction. A mentally stressful situation may require a physical response or action, but what about those psychological or emotional stressors that may be difficult but don’t actually pose any pressing physical dangers?
Stressors related to pressures of a work project requiring focused concentration over long days and nights, or the continual emotional drain from a difficult relationship or financial hardship?

Prolonged mental stress can adversely affect regular lifestyle routines, including decisions we make about sleep, nutritional intake, and exercise and can even persuade us to imbibe in alcohol or drugs.

Mental and emotional stress have adverse effects (acute and chronic) on physical health and wellbeing and are directly linked to suppression of the immune system.

How acute mental stress affects physical health was shown in a study of college students during their final exams.
To see how mental stress affect immune health, researchers took blood samples and administered questionnaires about anxiety and depression to 24 college students during finals week.
Baseline values of these had been established by prior blood draws and questionnaires completed midsemester.
When compared to baseline levels, during finals week, there were elevations in pro-inflammatory cytokines along with increased reports of anxiety and stress.
It was also observed how stress can lead to prolonged wound healing time with reduced levels of anti-inflammatory cytokines and increases in pro-inflammatory cytokines.

Multiple studies evaluated the immune response in conditions of long-term and emotional stress. These conditions are similar to those found with caregiving of an ill or elderly relative, experienced after a difficult divorce and have even been reported as related to loneliness.

Studies have shown links between emotional stress and increased risk for viral illness, reemergence of latent viruses (Epstein-Barr, herpes simplex, and cytomegalovirus), and onset of autoimmune disease.
In other studies it was shown how long-term psychological stress is linked to poor cardiovascular health and increased risk for immune diseases such as inflammatory bowel disease, allergies, atopic dermatitis, and celiac disease.

Even children can be affected by psychological stress that results in a reduced immune response.
Children with a history of recurrent colds and flu turned out to have higher levels of psychological stress. These children had lower immunoglobulin ratios (IgA/albumin). Since Ig-A is mostly present in mucus where it protects us against invading viruses and bacteria, it is quite logical how a lower ratio reduces immune function and makes us more susceptible to colds and flu.

How to cope with stress?

While acute stress can be useful on some occasions, chronic stress most certainly can play a role in both acute and chronic illness.
The best strategy to cope with chronic stress is a change of lifestyle such as meditation and excercise as well as improving your diet, by making sure to ingest enough essential nutrients such as omega-3 fatty acids, amino acids (glutamine, lysine), vitamins (B-complex) and minerals (zinc/magnesium).
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