How does stress weaken the immune system?

Answer 1

Stress affects the adrenal glands among other things. In fact that is the purpose of adrenal glands; to help you deal with stress from every possible source (psychological, environmental, infectious, physical, emotional, etc) and survive. The adrenal glands produce a number of different hormones that influence virtually all of the major processes in the body.
“Cortisol [made by adrenal glands] is a powerful anti-inflammatory hormone that, in small quantities, speeds tissue repair, but in larger quantities depresses your body’s immune defense system... Cortisol also reduces the rate at which lymphocytes [immune cells] multiply and accelerates their programmed cell death to further protect the body from this overreaction. In fact, when cortisol is elevated during the alarm reaction there is almost a complete disappearance of lymphocytes from the blood. That is why your immune system is suppressed when your are under stress or taking corticosteroids. On the other hand when circulating cortisol is low, its moderating effect on immune reactions is lost and lymhocytes circulate in excess.” Dr. James Wilson This creates more inflammation.
Continued stress raises cortisol levels. Cortisol slows the production of “good” prostaglandins. Prostaglandins (localized hormone like cellular messengers) are derived from essential fatty acids like fish oil. “Good” prostaglandins support immune function, dilate blood vessels, inhibit “thick” blood and are anti-inflammatory. Slowed production allows for the opposite - inflammation, immune suppression, etc.
The website below explains it in more detail, because it is actually a long list of things that happen when we are stressed. Many things are affected. Hope this helps!

Answer 2

It cause a surge in certain stress hormone that I think suppress the immune system. I know that is does very bad things to the body. Raise the blood pressure, etc. I am not a medical person, just read a lot.

Answer 3

It's a very complex biological/psychological response system, but I've linked to a good resource below. Basically, as I understand it, stress induces our flight or fight reflex which revs up our metabolism, blood pressure, etc. It's a complex system, even the world's best scientists are still unravelling it. When cells in the lab are exposed to stress (chemicals, heat, physical force) a cascade of resposes occur: stress proteins are created (called heat shock proteins) and the cellular machinery/metabolism changes. Mammals respond to stress in two basic ways: fight or flee. We humans live in environments, like the workplace, where we can run away or physically fight what is threatening us (the Boss or a client) so we live in 'chronic stress', which is a constant low-level stress. It can be devastating.

I guess to put it simply: stress makes the immune system work harder, and thus deplete its resources faster.

Answer 4

it wears you down. you may have trouble sleeping or a decreased appetite. therefore, you wouldn't be getting the energy that you need and it makes you more apt to come down with an illness.

Answer 5

http://www.hhmi.org/cgi-bin/askascientist/highlight.pl?kw=&file=answers%2Fimmunology%2Fans_011.html