Griffiths recently published a study in The Journal of the American Medical Association along with Dr. Eric Strain, also of the School of Medicine, which confirmed caffeine is addictive.

The study, sponsored by the National Institute on Drug Abuse, found more than 80 percent of adults consume caffeine in some form, with coffee, tea, soda and chocolate as the most common sources.

The average adult ingests about 280 milligrams of caffeine a day, which equals out to about two large cups of coffee, according to the study.

At those amounts, caffeine tends to have a positive effect on the body, Griffiths said. People tend to feel more awake and alert, he said. But in higher doses, caffeine can produce anxiety and nervousness.

Dependency

An actual addiction is much more serious than physical dependency, Griffiths said. A true addict will gradually develop a tolerance to the effects of the substance and experience withdrawal symptoms when the substance is no longer consumed.

Addicts persistently use a substance even if it causes or aggravates medical problems, and they are usually people who have attempted and failed repeatedly to stop using the substance.

Kristy Christian (senior-speech communication), a manager at Irving's Bagels, 110 E. College Ave., agreed that for some people the need for caffeine is like the need for a drug. "Coffee is definitely like a cigarette," she said. "You feel like you need a coffee fix."

Christian said she sees customers who depend on having their coffee every day. Regular customers come into Irving's so often -- at least three to five days a week -- that employees know what they are going to order, Christian said. Some even come in twice a day to get a refill, she added.

"We have a lot of repeat customers," she said. "There's a lot of kids who sit and drink coffee for hours."

Risks and symptoms

Like with drugs such as heroin, cocaine, nicotine and alcohol, people can become psychologically dependent on caffeine.

But caffeine use differs from classical drug use because it poses no life threatening risks, Griffiths said.

In increased doses caffeine acts more like nicotine and produces noxious effects, which makes you feel sick if you ingest too much, Griffiths said.

Griffiths said it is important to be aware of the similarities and differences between caffeine and other stimulants. Both can produce physical and psychological dependency, but the physical dependence caffeine produces is much weaker than dependence other stimulants cause, he said.

Breaking the addiction

Most people who are dependent on caffeine will experience some withdrawal symptoms if they stop their use. Fifty percent of people who use 100 milligrams of caffeine daily, which equates to one strong cup of coffee or three sodas, will experience headache and fatigue if they stop their use, Griffiths said.

Most people think it's easier to stop drinking caffeine than to stop using another stimulant like nicotine, but there aren't a lot of studies that prove that, Griffiths said.

Twenty years ago, people said the same thing about cigarettes they're saying about caffeine now — that it was just a habit they enjoyed, and it wouldn't hurt their health in the long run.

However Lori Waters, adviser for Penn State's Alcohol Intervention Program and community health educator for University Health Services, said addiction to nicotine is the hardest to break. Caffeine and nicotine both raise a person's heart rate and energy level, but caffeine can be cut back gradually, a process that takes much less time than it does to cut back on smoking or other types of nicotine use.

Mary Marks (senior-English) said she used to be addicted to Mountain Dew and would drink five or six cans of the soda a day until last year.

She didn't experience withdrawal symptoms when she quit, however, because she slowly cut back on the number of drinks she had a day.

Overuse of caffeine can cause physical dependency because people tend to develop a tolerance for it the more regularly they use it, said Dr. Steven Adelman, of the Harvard Vanguard Medical Associates.

Adelman said he has seen patients who appear to suffer from a psychological disorder with symptoms of anxiety and insomnia, but they really are just addicted to coffee, an illness he calls "caffeinism."

Adelman said these people have extreme problems with ingesting large amounts of caffeine and drink about a gallon of caffeine a day, equal to two two-liter bottles of coke.

Students with further questions about addictions and behavioral health problems can get professional advice by e-mailing an expert through a Web site Adelman helped establish, www.HeadDocs.com. The site also posts regular discussions about addictive behaviors.

Social function

The social aspect of going out for coffee also plays a part in the boom in the coffee industry, Christian said. Some people who don't normally drink coffee will when they're out with a group of friends.

People generally start using caffeine for the same reasons they begin using cigarettes and alcohol — because they are in a social setting and that's what their friends or most other people are doing, Griffiths said. Over time, however, they will develop a dependence, he said.

Some reasons to give up caffeine use are that it can aggravate problems for people who are chronically anxious or suffer from panic attacks or insomnia, Griffiths said.

Some kinds of stomach disorders and cardiac problems are worsened with the use of caffeine as well, Griffiths said.

Phil Miller (senior-life sciences) said until about a year ago he used to be addicted to coffee and would drink as much as three cups a day for five to six years.

He's since cut back to one cup of decaffeinated coffee a day, but still drinks a cup of regular coffee before he exercises. "Supposedly it loosens fat cells so they burn off faster," Miller said, "and it increases your metabolism."

Miller said he started drinking coffee at the young age of 8 and, although he's cut back drastically on the amount he drinks, his tolerance is so high he can still drink a double espresso and fall asleep.

Mary Dzielski (freshman-English) said she drinks coffee every day but doesn't physically crave it like an addict needs a hit or needle.

"I like to drink it while I'm reading to relax and unwind," she said.

Miller and Dzielski both said they occasionally drink coffee to stay awake in class or up late studying.

Some people don't need coffee for their caffeine kick. Although he doesn't drink coffee, Michael Crowley (senior-English) said he still gets his caffeine fix three times a day with Mountain Dew or Dr. Pepper.

"It keeps me up and going and keeps me energized," Crowley said.

Crowley said he likes caffeine most because of its energizing effects. "If I could snort Mountain Dew, I would," he said, adding quickly he has never snorted other stimulant drugs like cocaine.