Scientists have discovered a new 21st century illness which could seriously hit us all. Facebook envy is defined by being a depression we experience when we see our friends having better lives than ourselves.

A study conducted jointly by two German universities found rampant envy on Facebook and apparently this is triggering feelings of misery and loneliness. The researchers found that one in three people felt worse after visiting Facebook and more dissatisfied with their lives. People who browsed without contributing were affected the most.

Researcher Hanna Krasnova from the Institute of Information Systems at Berlin's Humboldt University said that she was surprised by how many people have a negative experience from Facebook with envy leaving them feeling lonely, frustrated or angry. Holiday photos were the biggest cause of resentment with more than half of envy incidents triggered by holiday snaps on Facebook.

Dealing with other Facebook users could also get you down. Users apparently compare how many birthday greetings they received to those of their Facebook friends and how many "likes" or comments were made on photos and postings.

"Passive following triggers invidious emotions, with users mainly envying happiness of others, the way others spend their [holidays] and socialise," the researchers said in the report "Envy on Facebook: A Hidden Threat to Users' Life Satisfaction?" released on Tuesday.

People aged in their mid-30s were most likely to envy family happiness while women were more likely to envy physical attractiveness.