Devoting too much time browsing the internet may cause depression, reveals the first major study into the effects of web use on mental health. The study, carried out by researchers at Leeds University, looked at the internet habits and mental health of 1,319 adults and young people based on online questionnaire in which people were asked how much internet they used and for what purpose .

The study showed that 1.2% people surveyed were identified as "internet addicts" and suffered from depression. They exposed themselves to sexually gratifying websites, gaming websites and sites that serve as a replacement for real-life socializing, such as Facebook and Twitter.

Author Catriona Morrison, in the journal Psychopathology, writes, "This study reinforces the public speculation that over-engaging in websites that serves to replace normal social function might be linked to psychological disorders like emotional depression and has a serious impact on mental health".

Excessive internet use is associated with depression, but what is unknown is the fact that what comes first - are depressed people drawn to the internet or does the internet cause depression.

But evidence suggests that active pursuits such as exercise and socializing with people face-to-face, help to stay healthy mentally.