How Stress Affects the Immune System

immune defence a shield protecting the body
Stress levels in our body – particularly if the body or brain is in an overwhelmed state where it cannot effectively dissipate or adapt to this stress – can have a harmful or depressing effect on our ‘immunocompetence’ – the ability of our immune system to do it’s job and fight internal and external threats.

This article is intentionally brief and does not outline in detail the full impact of stress on our immune system.

Elsewhere on this site we have outlined the impact of a chronic fear/protection stress reaction, particularly as it relates to the chronic release of stress hormones – one class of which are called glucocorticoids (cortisol is an example).

These stress hormones have body-wide effects.

One of these effects is a prioritisation of resources (energy, oxygen, blood flow etc.) away from some systems and organs, leading to reduction in their functional activity - usually this is about reducing the consumption of energy by what are considered 'less essential' systems while the brain perceives that an attack is imminent.

Instead these resources are sent mainly to priority areas such as the brain and muscles.

“You don’t need white blood cells to fight an infection, unless you have successfully avoided the lion and have to recover from the lion’s bite”

The immune system is ‘metabolically expensive’ – it takes a lot of energy to run effectively!

However, putting aside the issue of energy expenditure, it is useful to understand that our immune system has two main ‘arms’ – one is called the ‘cellular’ (or Th1) response, the other is called the humoral (or Th2) response.

These two arms of the system tend most of the time to be well-balanced, working in concert with each other.

Anything that causes a shift away from this balance, especially toward Th2 as the dominant type of immune response, leads to major problems with overall immune function and increased susceptibility to atopic, auto-immune, cancerous and many other conditions. 

What do you think one of the main results of stress hormones is on this balance?

That’s right, they lower the production of special intermediary communication chemicals like interferon and interleukins, and the result is less Th1 response, and more Th2!

So stress LOWERS immunity – plain and simple.

This makes common sense – how often do you get sick when you are really stressed out?

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