Observing another person in a stressful situation can be enough to make our own bodies release the stress hormone cortisol, the study from the Max Planck Institute for Cognitive and Brain Sciences in Leipzig and the Technical University in Dresden found.
The contagious affect is particularly bad among couples, but even seeing stressed-out strangers is enough to increase the observer’s stress levels, the study found.
"The fact that we could actually measure this empathic stress in the form of a significant hormone release was astonishing," said Veronika Engert, one of the study’s authors.
During the stress test the subjects were given difficult mental arithmetic tasks and interviews, while being watched by another subject.
The impact of the stress was particularly high when the observer and stressed individual were in a relationship, with 40 percent of observers also getting stressed.
Even when watching a complete stranger, the stress was transmitted to ten percent of observers.
And another 24 percent of observers became stressed when watching the tests over video.
"This means that even television programmes depicting the suffering of other people can transmit that stress to viewers," Engert said. "Stress has enormous contagion potential."