In the past several years, psychologists and other academics have begun to study what is known as "Internet addiction" or "problematic Internet usage."

No matter which term is used, there is little doubt that overuse of the Internet is becoming a major mental heath issue, officials say.

Addiction cannot be determined simply from the number of hours spent online; the context of the usage is what determines if there is actually any problem.

Richard Davis, an expert from York University in Toronto, said there are two major indicators of Internet addiction.

First, usage must be so high that it begins to interfere with daily life, such as relationships, occupations and/or academics.

Second, the user must have difficulty stopping.

Davis said Internet users fall on a bell curve ranging from "computer anxiety" to "overly-engaged."

Research estimates that about 3 percent of those who go online may suffer from problematic usage. These users can fall into one or more of four categories.

The first group has a lack of impulse control, showing difficulty in controlling their inherent desire to stay online for long periods of time.

The next group goes online when they are lonely or depressed.

They go to the Internet to get cured, but most often do not succeed in finding solutions.

The third group seeks social comfort on the Web by meeting other people online and communicating in chat rooms and on message boards for people with common interests.

The last category, the one that university students are most likely to fit in, uses the Internet to avoid coping with stresses such as exams and papers. Davis says that this is not necessarily bad.

Taking five- to 10- minute breaks from work to play an online game or chat with friends is called adaptive behavior, and is beneficial.

This risk comes from maladaptive avoidance, which can cause a cycle of stress, excess time online, a bad score on the test or paper, depression and even more stress.

A recent study has shown that Internet addiction is now the No. 1 reason to be reprimanded at work in the United Kingdom.

Excess Internet usage can also create physical manifestations such as lack of sleep or weight gain caused by inactivity.

College students are at the highest risk of Internet addiction for several reasons dealing with their place and situation. They are still exploring their identities and sexuality, and the anonymous nature of the Internet allows them to do that.

College is the first time most students are away from their parents and may feel alone, which draws them to the Internet for comfort.

Finally, most students don't have much money to spend, and the Internet gives them a form of "cheap entertainment."

Davis said Internet addicts are hooked to various types of online activities such as games, casinos, stock trading, auctions, and pornography, adding that pathological Internet use (PIU) "is similar at the core to pathological gambling."

He says that there are high incidence rates of PIU all over the world, in both rural and urban areas of various countries.

One of the most interesting findings of Davis' research is that Internet addiction may have cognitive underpinnings, not just behavioral ones, meaning that those who suffer from PIU may actually have brain activity completely unlike those who don't.

However, Gerry Santoro, assistant professor in the School of Information Sciences and Technology, said Internet dependency is a behavioral problem lacking the clear physical aspects seen in alcohol and tobacco addictions, though he feels that it can be just as dangerous.

Santoro said some behaviors are reinforced, possibly causing addiction.

"If people get rewards online, they will become their preferred method of social interaction," he said.

A dangerously strong addiction to the Internet can be especially prevalent in those with existing social and emotional challenges, Santoro said.

He said online chatting no longer carries the stigma it once did. Santoro said the nature of human interaction is evolving.

"Computers are natural," he said. "They are a way people interface with the world."

People need to re-examine how they judge Internet addiction, according the experts.

The primary question is whether users are actively engaged and learning while they spend time online, Santoro said.

Still, he said, "too much of anything can become a problem."

He proposes that proper use of the Internet be integrated into school curricula.

Ben Eisenberg (junior-information sciences and technology) said at the beginning of his college education, it became apparent to him how many students were addicted to instant messenger programs.

"We would literally spend hours trying to communicate with friends back home and at other colleges," he said.

He said he thinks students' Internet addictions can be caused by boredom, loneliness, distractions, too much free time or a need to communicate inexpensively.

Eisenberg said the likelihood of remaining an Internet addict decreases with each year students spend at school because the novelty of talking online decreases.

Santoro said there is no discussion in academic circles about "communication addiction," when in reality mostly what the Internet is about.