For most, it?s just the thing to get the morning started. For some, it?s an obsession – a hot cup of coffee can mean the difference between a good day or an awful day.

Nicole Rathburn, a sophomore majoring in art and spanish, started drinking coffee with her grandmother when she was 13 years old. Like other coffee drinkers on campus, her obsession with dark, silky brew began early.

The active chemical contained in coffee is caffeine and has been a part of American society for decades. Coffee has been popular both in diners, where it?s called “Joe,” and in dark smoky shops frequented by hipster beatniks, where “java” is the preferred term.

Recently, however, cheaper and faster methods of brewing, along with the introduction of designer flavors from Europe, has made coffee a mainstay for nearly everyone in this country.

Nowhere is this more apparent than at universities, where students line up at coffee shops all day, either for an early morning boost or an afternoon pick-me-up. With a coffee cup in one hand and a purse or bag slung around the shoulder, this beverage has become as much a necessity as it is an accessory.

Once you?re hooked, skipping your morning cup makes your blood pressure drop dramatically, causing a blood rush to the head that leads to a headache.

Reports of irritability, nervousness, sleepiness and an inability to work are all effects of caffeine withdrawal. This is a serious matter when one-half of Americans drink coffee, making it the most popular drink in the Unites States, according to the Java City website.

Jared Cavaness, a junior business major, said he doesn?t need coffee, but it sure does help.

” I feel like I do much better with it. Coffee makes me more alert in class and for students who have to work long hours and don?t get a lot of sleep it becomes almost a necessity,” he said.

Caffeine is found in cola nuts, coffee, tea, malt and other plants. When caffeine in these products is consumed orally, it acts as a stimulant to the central nervous system, cardiac muscle, respiratory system, affects the body as a diuretic and can act as a muscle relaxant or stimulant.

The caffeine content in these cups varies by ingredients and drink concoctions vary in complexity.

The menu at Java City features relatively simple drinks like coffee and lattes and blended drinks such as a caramel macchiato, which has vanilla syrup, a shot of espresso, steamed milk and a decadent drizzle of caramel.

“I usually order a medium white chocolate mocha at least once a day,” Rathburn said.

Rathburn?s daily dose of caffeine contains 200 mgs of caffeine from 2 shots of espresso, but this drink is an example of how caffeine has been shown to combine with other substances for added potency. Cocoa contains eight times more stimulant than caffeine. Thus, the effects of caffeine might be enhanced by the caffeine in chocolate.

Cavaness orders a 16 ounce Tuxedo, which has white and dark chocolate with shots of espresso from Java City four days a week when he has class.

“I was ordering an extra shot with my drink, but I had to quit. When I have too much caffeine I begin to get the jitters,” Cavaness said.

Java City offers cups in three sizes, 12 ounce, 16 ounce and 20 ounce. As a Java City rule, one shot of espresso is added to a 12 ounce drink, 2 shots to a 16 ounce drink and 3 shots to a 20 ounce drink.

One shot of espresso contains 100 milligrams of caffeine and one regular 7 ounce cup of drip coffee contains between 115 to 175 mg of caffeine, depending upon the potency of the roast. Home brewed coffee contains 80 to 135 mg.

If you prefer tea to coffee, iced tea contains 70mg, and regular instant or brewed tea contains anywhere from 30-70 mg of caffeine.

Comparatively, a 12 ounce cola can contains 30-45mg and a chocolate bar contains 30 mg of caffeine.

In the United States, there is a limit of 6mg of caffeine per liquid ounce in beverages. This means a 20 ounce cup of coffee is only supposed to contain 120 mg of caffeine. However, a single serving of espresso contains 100 mg. A 20 ounce cup contains 3 shots of espresso, which equates to 300 mg of caffeine. There is also a limit of 200 mg in pills such as Vivarin. In Australia the legal amount is 145 mg of caffeine per liter.

Although caffeine enhances the metabolism of fatty acids in the body, too much caffeine may be lethal for humans.

Symptoms of caffeine overdose occur when more than 250 mg (less than 3 shots of espresso) are consumed, according to the “DSM-3 from the American Psychiatric Association.”

If an individual has at least five of the following symptoms they may be at risk of caffeine toxicity levels. These symptoms are: restlessness, nervousness, excitement, insomnia, flushed face, gastrointestinal disturbances, muscle twitching, rambling flow of thought and speech and other psychological disorders.

The lethal dose is believed by health professionals to be 52 shots of espresso or 50 Vivarin pills of 200 mg each, amounting to about 3.2 grams of caffeine.