Des chercheurs allemands sont arrivés à la conclusion que le stress est contagieux et que la seule vue de quelqu'un de stressé, via une vidéo par exemple, peut provoquer une secrétion de cortisol (l'hormone du stress):
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Stress is contagious. Observing another person in a stressful situation can be enough to make our own bodies release the stress hormone cortisol. This is the conclusion reached by scientists involved in a large-scale cooperation project between the departments of Tania Singer at the Max Planck Institute for Cognitive and Brain Sciences in Leipzig and Clemens Kirschbaum at the Technische Universität Dresden. Empathic stress arose primarily when the observer and stressed individual were partners in a couple relationship and the stressful situation could be directly observed through a one-way mirror. However, even the observation of stressed strangers via video transmission was enough to put some people on red alert. In our stress-ridden society, empathic stress is a phenomenon that should not be ignored by the health care system.
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via http://rt.com/news/156228-stress-contagious-say-scientists/