Facebook posts can affect your mood and spread like wildfire through friends, a new study revealed this week.

Researchers found that seeing positive posts really did boost people’s moods, but that a negative post had the opposite effect.

The results even lead to users sounding happier or more fed up in their status updates, and seeing fewer emotional posts led to people being less expressive.

The study by social scientists at Cornell University, the University of California and Facebook is the first to suggest that emotions expressed via online social networks influence the moods of others.

The researchers reduced the amount of either positive or negative stories that appeared in the news feed of 689 003 randomly selected Facebook users and found that the ‘emotional contagion’ effect worked both ways.

“People who had positive content… reduced on their Facebook news feed, for one week, used more negative words in their status updates,” reports Cornell professor Jeff Hancock. “When news feed negativity was reduced, the opposite pattern occurred.”

He said peoples’ emotional expressions on Facebook predicted their friends’ expressions, even days later.

“We also observed a withdrawal effect: people who were exposed to fewer emotional posts in their news feed were less expressive overall on the following days.” – DailyMail