basis, cortisol helps maintain the body’s circadian
rhythms, which regulate sleep and appetite, and it
does other basic things with [cellular] growth and
repair, with helping the glucose response and with
amino acid production,” Kertes says.
During periods of stress—either acute or
prolonged—cortisol levels increase. Although cor-
tisol is commonly associated with a rise in inflam-
mation, its short-term function is actually to quell
the surge in inflammation that stress has instigated,
Kertes says. If a person is experiencing a bout of
stress, this is exactly what tends to happen; cortisol
floods the blood and calms down all those excited,
inflammation-stoking immune cells.
But if stress persists and cortisol levels remain
elevated for long periods, the body’s immune cells
and related systems become “desensitized” to cor-
tisol’s calming effects, Kertes explains. This de-
sensitization can cause inflam-
mation to rage out of control.
It also blocks cortisol’s typi-
cal “repair and maintenance”
work, she says. Further, corti-
sol can bind to DNA and alter
gene expression. That is one
way excessive stress can affect
how our organs and tissues are
functioning, Kertes says.
While chronic stress leads
the immune system to become
desensitized to cortisol’s help-
ful actions, the brain is becoming increasingly sen-
sitized to stress. “If you’re continually exposed to
stress, you’re teaching the brain that it exists in a
toxic, threatening environment and that it needs to
be on alert all the time,” Kertes says. “So it becomes
hyperresponsive.” In other words, feeling anxious
or stressed tends to breed more anxiety and stress.
Even brief bouts of stress can exacerbate exist-
ing health conditions. But chronic stress is a risk
factor for a wide range of diseases and disorders.
These include several types of cancer—including
those of the breast and prostate—as well as Type 2
diabetes. They also include many conditions peo-
ple don’t tend to associate with stress, such as
Alzheimer’s disease, infectious diseases and pain
disorders, Kertes says.
Heart disease is another health issue that re-
search has tied to stress. “People who are chroni-
cally anxious or stressed are going to have more
inflammatory markers, more dysfunction of the en-
dothelial lining of the blood vessels and overactivity
of the sympathetic nervous system, which changes
how the heart beats,” says Christopher Celano, as-
sociate director of the Cardiac Psychiatry Research
Program at Massachusetts General Hospital.
Some of the latest and most compelling re-
search on stress has to do with its effects on the gut.
“Stress can affect several aspects of normal gastro-
intestinal physiology—everything from influencing
the secretion of gastric acid and other digestive en-
zymes to changing motility patterns both in the
small and large intestines,” says Michael Bailey, an
associate professor of biosciences, microbial in-
fection and immunity at Ohio State University’s
Wexner Medical Center. Bailey has studied the ef-
fects of stress on the gut and immune system. He
says all these stress-induced shifts can worsen
symptoms for people with GI
disorders, but they can also
cause short-term stomach pain,
constipation or other gut issues
in healthy folks.
Stress can also change the
composition of the gut’s eco-
system of bacteria, which are
collectively known as the mi-
crobiome. “During normal,
healthy periods, the composi-
tion of the microbiome is pretty
steady and consistent,” Bailey
says. But during periods of stress, “the composi-
tion does change quite a bit,” he adds. “In individu-
als with some bowel disorders—irritable bowel dis-
ease, in particular—we know stress can exacerbate
these diseases, and it looks like that’s associated
with changes in the composition of the microbiota.”
Bailey says prolonged periods of stress are the
greatest concern when it comes to gut health.
“Stress is a normal part of everyday life, so avoid-
ing it is really not possible,” he says. “What’s impor-
tant is making sure that stress response is acute and
short-lasting, rather than something that festers for
long periods of time.”“GOOD” AND “BAD” STRESS
brief, Minor bouts of stress are soMetiMes
referred to as “good” stress because they can be
motivating. This sort of stress can focus a person’s
attention and energies and thereby help him or herTHE SCIENCE OF STRESS DEFINING STRESS
When anxiety
and stress run
rampant, many
of the body’s core
protective processes
are disrupted.