(CNN) -- The body's immune system is a true fighter -- protecting
people from disease by keeping viruses and bacteria from taking over and
ruining our health.
But one thing the immune system can't always fight is stress. Studies
have shown that a stress-ridden immune system operates on a weakened
level, making the body more vulnerable to cold viruses and other
The effect can be even greater on patients whose immune systems are
already compromised. Researchers have found that people infected with
HIV, the human immunodeficiency virus, are at greater risk for the
lethal disease AIDS. Another study showed severe stress increases a
breast cancer survivor's risk of relapse -- by a factor of six times.
So why does how we think and feel and the kind of environment we're
exposed to matter so much to our health? Psychologist
has to do with the "balance" our immune system holds in fighting
"Especially for people in their sixties and seventies (years of age),
stress appears to matter a great deal more," said Kiecolt-Glaser, of
Ohio State University. "But even for younger people, there's good
evidence that even things like colds and flu can be enhanced by
relatively minor stressful life events.
"When people are stressed, small alterations in immune function may
actually help tip the scales and increase the odds" of someone getting
sick, she said.
Stress can send the immune system into a tizzy, triggering the
pituitary gland to release a hormone called ACTH. ACTH then stimulates
the adrenal gland to release another hormone called cortisol, which
attaches itself to the immune system's disease-fighting cells.
With a load of cortisol on its back, an immune cell has a harder time
doing its job.
But not all stresses are created equal, experts said. Getting stuck
in traffic, for instance, sounds and feels frustrating. But
psychologists say travelers know the traffic crunch will be over -- and
that helps to keep the immune system somewhat protected from stress.
Longer-term stresses like a divorce or a remembered traumatic event,
however, can do a number on the body's ability to fight off infection.
Keeping it alive in your mind, Kiecolt-Glaser said, allows stress to do
battle with a person's immune system.