LONELY? Depressed? Don't blame it on stress, work pressure or even physical ailments. It could be because of excessive use of the Internet, say researchers at the Carnegie Mellon University in Pittsburgh, USA.

Studying the retreat of the human race indoors, researchers have found that too much time spent on e-mail and on online chat rooms increases your sense of loneliness and depression, causes you to break friendships and weakens your bond with family members.

The two-year study, the first of its kind, was published in The American Psychologist, a monthly journal of the American Psychological Association. An analysis of the behaviour of 169 participants selected from four schools and community groups was conducted in the Pittsburgh area. Half the group was assessed through two years of Internet use and the other half over one year.

At the beginning and end of the study, the subjects were asked to answer statements like, "I felt everything I did was an effort"; "I enjoyed life" and "1 can find companionship when I want it". They were also questioned about their social circle and were asked to estimate how much time they spent with their family each day. Many of these are questions asked to determine a person's psychological health.

The participants' use of the Internet was recorded for the duration of the sludy. Depression and loneliness were measured independently and each person was rated on a subjective scale. In measuring depression, the responses were plotted on a scale of zero to three with zero being the least depressed and three being the most. Loneliness was plotted on a scale of one to five. On an average, Internet use of one hour a week led to an increase of 0.3 or one per cent on the depression scale; a loss of 2.7 members of the subject's social circle which averaged 66 people; and an increase of 0.2 or four-tenths of one per cent on the loneliness scale.

Teenagers seemed to be most affected by the cyber malaise, perhaps because they spend most of their time in chat rooms. Though most of the participants said they used the Net for social activities, the effects were statistically significant in demonstrating deterioration of social and psychological life. "Socialising via computer screen turns out to be less fulfilling than other methods of human interaction. It's like spending all your life at a cocktail party," says Robert Kraut, a sociology professor who led the study.

The study did not try to identify the reasons for the apparent antisocial effects of the Internet. However, the researchers offer two possible explanations:

• The amount of time devoted to direct human contact is considerably reduced by the use of computers. Thus making it no different from television. Says Kraut, "It's one more thing that's taking you away from the real life."

• Online relationships are less fulfilling than face-to-face ones. They often involve strangers or are limited to just one subject. Without visual and aural links, communications are less rich than face to face ones or even those over the telephone. "The result is more degraded interaction," says Kraut.

The results of the us $1.5 million project has come as a rude shock to social scientists who designed the Internet as a means of communication and to many of the organisations that financed the study. These include technology companies like Intel Corp, Hewlett-Packard Co, AT&T Research and Apple Computer Inc, as well as the National Science Foundation.

"We were shocked with the findings, because they are counter-intuitive to what we know about how socially the Internet is being used," says Kraut. "We are not talking here about extremes. These were normal adults and their families, and on average, for those who used the Internet most, things got worse."

But how authentic are the findings? Several social scientists familiar with the study vouched for its credibility and said it could spark off a nationwide debate in the us over the country's Internet policy. "They did an extremely careful study and it's not a result that is easily ignored," says Tora Bikson, a senior scientist at Rand, a research organisation. "But," says Christine Riley, a psychologist at Intel Corp, "for us the point is there was really no information on this before. It's important to remember this is not about technology per se. It's about how it is used."