JULY/AUGUST 2019. DISCOVER 55
Why So Stressed?
Ancient organisms likely evolved
the stress response to better escape
from predators. But today’s triggers
include traffic, deadlines and first
dates. According to a 2018 American
Psychological Association survey of more
than 3,000 respondents, the top stressors
are work, money, the economy and health.
Although everyone faces stress,
people react to it differently. “There’sthe situation, how we evaluate the
situation, and then our skills at handling
the situation,” says psychologist William
Lovallo of the University of Oklahoma.
Previous experiences help us gauge
appropriate responses, so most people
improve with age. “A high school student
or a college student might not have those
coping skills and might let a situation get
out of hand,” he adds.
Most adults have normal stress
responses, calibrated to give the right
burst of hormones and bodily changes
for a particular stressor. But others
consistently over- or underreact, which
may be a warning sign for physical or
mental disorders. To study this, scientists
often monitor cortisol or heart rate
fluctuations throughout the day and
during trying tasks.
In some cases, the intensity of theseresponses seems to be set from a young
age. Studies have shown that people
who experienced childhood hardships
— including physical punishment, an
unstable home and sexual abuse — are
more likely to have muted stress reactions
as adults. For example, as part of a study
published in 2012, Lovallo exposed 354
participants to moderate stress. People
who self-reported early-life adversity
actually had lower heart rates and cortisol
levels than other participants. While the
study tasks were inconsequential, the
individuals’ underreactions suggest their
stress response may also have trouble
revving up when it really matters, which
can be just as unhealthy as an excessive
response. Other research has found links
between childhood strife, abnormally low
adult stress and substance abuse. Though
the biology is not fully understood, it’s
suggested that early-life neglect ortrauma desensitizes the body’s stress
pathways.
Even before birth, a child can inherit
parental stress, either through hormones
the developing fetus takes in or chemical
modifications to the egg or sperm. The
phenomenon is well-demonstrated in
rats and mice, and some papers have
shown the same association in humans.
For instance, adult children of Holocaust
survivors and babies born to mothers
experiencing PTSD from the 9/11 attacks
all had low cortisol levels.
Younger People Feel More Everyday Stress...
... and Stress More Over Stories in the News
Work
Money
Health-Related
ConcernsEconomy
Mass
ShootingsRise in
Suicide RatesClimate
Change77% (feel stress)
64% (feel stress)
81%
64%75%
63%46%
48%75%
62%62%
44%
58%
51%Ages 15-21 Ages 22+
How Our Bodies React to Stress
The
hypothalamus
starts the SAM
pathway by
sending signals
via nerves to the
adrenal glands,
which release
the hormone
adrenaline (aka
epinephrine).To start the
HPA axis, the
hypothalamus
sends
corticotropin-
releasing
hormone (CRH)
to the pituitary
gland.Adrenaline
causes a fight-or-
flight state, with
increased heart
rate, sweating,
blood sugar and
oxygen intake.The pituitary
gland sends
andrenocorti-
cotropic hormone
(ACTH) to the
adrenal glands,
which release the
hormone cortisol.Cortisol keeps
the body on
high alert,
perpetuating
the initial stress
response.Adrenal
glandsO
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SHORT TERM LONG TERM
Source: American Psychological Association, 2018When a stressor occurs, the amygdala region perceives the threat and
sends a distress signal to the hypothalamus, which acts like a command
center. It kicks off a stream of hormones along two pathways: the
sympathomedullary (SAM) and the
hypothalamic pituitary adrenal (HPA) axis.ACTH
CRH
Hypothalamus
Pituitary
CORTISOL