In the study, which was published in the journal Psychoneuroendocrinology, participants took a stress test involving mathematics and interviews. Although a few subjects managed to keep their cool, 95% displayed an increase in cortisol, a steroid hormone known to increase two to five times during physical and psychological stress. Meanwhile, another group of test subjects, called “observers,” watched the initial participants complete the stress test through a one-way mirror.
Cortisol levels increased significantly in 26% of the observers, meaning just watching someone anxiously tackle a challenge was stressful enough to induce a secondhand, physiological response. Even more fascinating: When subjects observed their significant other through the mirror, 40% saw an increase in cortisol levels. While emotional closeness may cause a stronger response, the study suggests witnessing anyone experience a difficult situation can be stressful. And, though previous research suggests women are more empathetic than men, this particular study found men and women experienced empathic stress reactions equally.
While a spike in cortisol is an important evolutionary response to danger, researchers say continuous increases in the hormone can be dangerous in the long-term. From blood pressure regulation to metabolism, cortisol plays a role in a number of bodily functions. Too much of the hormone has been associated with risk factors for cardiovascular disease, including insulin resistance and decreased levels of HDL cholesterol (that’s the good kind).
So, back to that Discovery Channel special. The researchers contend we can actually “catch” someone else’s stress via the small screen. After the one-way mirror experiment, they showed videos of individuals completing the stress test. This time, 24% of observers had increased cortisol levels — nearly the same as when they watched the action live. While the Everest avalanche coverage probably struck a more impactful chord, there's good reason to think even fictional drama (we're looking at you, Law & Order: SVU ) could induce harmful stress, too.
More research is necessary to figure out why, exactly, we respond to others’ stress — and how we can prevent ourselves from “catching” it. Unfortunately, while it’s easy to turn off the TV, we can’t exactly turn off a stressed friend, partner, or coworker. So, while it's not always our duty to assuage others' worries, reducing someone's stress may in fact help us reach our own zen.