Facebook use increases jealousy in relationships, two University of Guelph student researchers say.

Moreover, the more time one person spends online on the social networking site monitoring his or her partner, the more suspicious that person becomes, the two said in a news release Friday.

PhD students Amy Muise and Emily Christofides found that the kind of interactions a person has on Facebook — social exchanges with friends and especially with previous partners — makes his or her partner jealous.

"In the past, people in romantic or sexual relationships were not, for the most part, subjected to daily scrutiny of their social exchanges by their partner," said psychology professor Serge Desmarais, who oversaw the research. "But this is the new reality for some: aspects of their lives that were once private are now open for all to see."

It's very common for Facebook users to include previous romantic or sexual partners as "friends" on Facebook, the researchers found through their survey of 308 student users of the site.

Most of the students said they were aware that Facebook increased their jealous feelings. But they said it was too hard to resist — especially the temptation to monitor their partner's page.

That information sets up a feedback loop, Christofides said.

"Jealousy leads to increased surveillance of a partner's Facebook page, which results in further exposure to jealousy-provoking information," she said.

All 308 subjects in the survey are university students between the ages of 17 and 24. About half were in a serious relationship.

The study will be published in the journal CyberPsychology and Behaviour.