Happiness and sadness may literally be infectious according to data from a long-term study.

The study measured changes in people’s emotional states over time by using a model developed to track patterns of how infectious diseases like SARS spread, TheStar.com reported.

Researchers from Harvard University used data collected from a long-term project called The Framingham Heart Study, which has tracked the social and medical information of thousands in Framingham Mass., every two years since 1948.

Click here to learn more about the Framingham Heart Study.

The participants, who totaled 1,880 when the study began, rated their emotional state as content, discontent or neutral at each visit. Their emotional states were monitored for changes over time and the researchers specifically focused on how changes in one person were affected by the emotions of those that they came into contact with.

The results suggested that happiness and sadness are contagious over long periods of time. But, when it came to participants returning to their original emotional state, they weren’t affected by the emotional state of those with whom they came into contact.

The research showed that participants “recovered” — meaning they returned to a neutral emotional state — from discontent quicker than content. What the researchers called a contentedness “infection” takes 10 years to wear off, while a discontentedness “infection” takes just five years.

The research dealt with such long-term emotional states because they measure general life satisfaction better than immediate or spontaneous emotions, like laughter, the report said.

Although participants recovered from discontent quicker, it was more contagious than content. The research showed that a person’s chances of being unhappy doubled when they had just one discontent contact, while a person’s chances of being happy rose 11 percent when they had a content contact. Happiness is also more likely to arise spontaneously than sadness.

While emotions can be contagious like disease, they also show that they can result from one’s own life events, rather than just being contagious.

This research was published in the July 7 Proceedings of the Royal Society B, a biological research journal.

Click here to read more from TheStar.com.