Have you ever been around a person in a particularly bad mood, only to realize that at the end of your interaction, you too have become sour? Or maybe you were around a group of giggling children and you found yourself struggling to hold back your own laughter. Research shows that if you spend enough time with people, their emotions will actually rub off on you, a phenomenon known as “emotional contagion.”

It’s the reason why you can’t help but smile back when someone is grinning at you. Emotional contagion is caused by an interconnected network of cells in the brain that make up the mirror neuron system (MNS). Mirror neurons fire both when a person acts and when a person observes the same action performed by another. The MNS is like a camera that records the details of people’s facial expressions, body language, pupil movement, and vocal tones. When you are around someone who is happy and smiling a lot, your MNS will not only pick up on those details, but it will also signal the same characteristics to be displayed in you. That’s not all that is happening. The MNS also contains emotional areas of the brain, helping you to mirror the emotional state of the happy person as well. So if you want to be happier, it would help to surround yourself with other happy people.

One interesting study published in Clinical Psychological Science found that men’s smiles become more contagious as they consumed beer. Researchers split 720 healthy social drinkers into groups of 3, with each given an alcoholic beverage, a non-alcoholic beverage, or a placebo drink. The groups were introduced and served their drinks at regular intervals. The men who were served alcohol “caught” smiles more readily than those who did not consume any alcohol, but only in all-male groups. Alcohol in mixed groups and in all-female groups, on the other hand, didn’t make smiles any more contagious than non-alcoholic and placebo drinks.

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Happiness is not the only emotion that can be contagious. Research has found that depression in a spouse tends to lead to depression in the partner, as was the same in roommates, as well as children raised by depressed parents. In fact, one family member’s depression is capable of bringing down an entire family’s emotions. Other emotions, such as anxiety and fear, have the same effect. Consequently, absorbing too many negative emotions for a prolonged period of time can have significant, long-lasting effects on the health and well-being of those experiencing them. The constant negativity results in second-hand stress, which has the same effects on a person as direct stress.

Emotional contagion isn’t just linked to face-to-face interaction either, but can affect people on social media as well. When Facebook removed positive posts from the news feeds of more than 680,000 users, they made fewer positive posts and more negative ones. When negative posts were removed, the opposite occurred. "These results indicate that emotions expressed by others on Facebook influence our own emotions," the authors wrote in a study published in the journal Proceedings of the National Academy of Sciences.

Emotional contagion has the power to be both good and bad. It’s a trait that has been with the human species for a long time and has helped our ancestors understand each other before spoken language was developed. It helped them, for instance, recognize fear by having the same feelings induced in them in order to survive potential danger. Moving forward, the best way to utilize the knowledge of emotional contagion is to surround yourself with happy people if you want to feel happier, and help raise the spirits of people who feel sad. 


  1. Bourg Carter S. Emotions are contagious—choose your company wisely. Psychology Today website. October 20, 2012. http://www.psychologytoday.com/blog/high-octane-women/201210/emotions-are-contagious-choose-your-company-wisely .
  2. Feltman R. When men drink, their smiles get more ‘contagious.’ The Washington Post website. September 30, 2014. http://www.washingtonpost.com/news/speaking-of-science/wp/2014/09/30/when-men-drink-their-smiles-get-more-contagious .
  3. Hamilton DR. Emotional contagion: are you feelings ‘infecting’ others? Huffington Post website. Updated July 19, 2011. http://www.huffingtonpost.com/david-r-hamilton-phd/emotional-contagion_b_863197.html .
  4. Lewis T. Emotions can be contagious on online social networks. Scientific American website. July 1, 2014. http://www.scientificamerican.com/article/facebook-emotions-are-contagious .