Watching a lot of videos, checking e-mail compulsively and switching frequently between applications are all signs of depression amongst Internet users, new research suggests.

The study looked at the web-surfing habits and depression levels of 216 undergraduate students at the Missouri University of Science and Technology.

It gauged the participants' mental health by having students fill out a questionnaire widely used to measure depression levels. They compared that to Internet usage data collected by the university's information technology department.

"This didn't mean snooping on what the students were looking at or whom they were e-mailing; it merely meant monitoring how they were using the Internet -- information about traffic flow that the university customarily collects for troubleshooting network connections and such," researchers Sriram Chellappan and Raghavendra Kotikalpudi wrote in a New York Times article discussing their work.

They found depressed students were more likely to check e-mail frequently.

"This perhaps was to be expected: research by the psychologists Janet Morahan-Martin and Phyllis Schumacher has shown that frequent checking of e-mail may relate to high levels of anxiety, which itself correlates with depressive symptoms," the study's authors wrote.

They also tended to switch more frequently between Internet applications, like chat, e-mail and games.

"This may indicate difficulty concentrating. This finding, too, is consistent with the psychological literature: according to the National Institute of Mental Health, difficulty concentrating is also a sign of depressive symptoms among students."

As well, they tend to watch more videos and share more files.

The researchers want to use their findings to develop something akin to net nanny software for the depressed.

"It would monitor your Internet usage and alert you when your usage patterns might signal symptoms of depression. This would not replace the function of mental health professionals, but it could be a cost-effective way to prompt people to seek medical help early. It might also be a tool for parents to monitor the mood-related Internet usage patterns of their children," they said.