More than half of Americans drink coffee daily, according to research at Syracuse University. For many, coffee's jolt is the best part of waking up.

"I couldn't live without it, I drink it every day," said a Hartford construction worker who said he drinks at least six cups of coffee before he arrives at work.

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Dr. Laura M. Juliano, an assistant professor at American University's Department of Psychology, has studied coffee and its affect on people.

"It feels good. It's a stimulant drug, so it makes people feel happy, more talkative, more sociable, more awake and alert," she said. "It has a rewarding effect on the brain chemicals. It's no different really from all drugs taken for recreational purpose, such as tobacco or alcohol."

Coffee or cola?

While typical soft drinks can provide a similar effect, the amount of caffeine they deliver generally is significantly lower. Research has shown that the beneficial effects observed in coffee are not replicated in other drinks.

"The caffeine in coffee tends to have a bigger bang for the buck," Juliano said.

Sue Gebo, a registered dietitian in Hartford, Conn., pointed out that coffee tends to serve as the better drink over soft drinks because the typical soda contains more than 100 calories, compared to a cup of black coffee, which has almost no calories.

"It's the stuff people add to coffee -- the cream, the extra cream, the sugar -- that can add 60 or more calories in a large coffee," Gebo said. "Then, the flavored syrups add significantly more calories."

Gebo also explained that coffee can camouflage normal hunger signals, but that wears off through the day.

"People are more likely to get out-of-control hungry when the caffeine wears off. When people are trying to lose weight, they might get into trouble," Gebo said.

As with anything we consume, however, side effects can accompany the benefits of caffeine in coffee.

What's in a cup?

What comprises a cup of coffee can vary by size, brew and bean.

A Florida study published in the Journal of Analytical Toxicology indicated a 100-mg difference between 16-oz. cups of coffee at Starbucks and Dunkin' Donuts.

"In general, there's such a huge variability. Researchers found that even if you ordered the same (cup of coffee from the same store every day), there's big variability in terms of hundreds of milligrams" of caffeine, Juliano said.

Juliano said as little as 100 mg of caffeine -- about a half cup coffee -- can spark symptoms of withdrawal, and 400 mg can induce a sense of anxiety and sleeplessness.

"The body makes adjustments and those adjustments feel negative. Then, we (start) to need the coffee just to feel awake and concentrate," Juliano said.

The experts said the common withdrawal symptoms include irritability, headaches, lethargy, fatigue, drowsiness and difficulty concentrating.

"When you skip a day and get headaches, that means you're addicted to caffeine," Gebo said.

Gebo said the effects can manifest in all people within 12 to 24 hours after stopping caffeine intake, and the symptoms could continue for as long as nine days.

Health benefits and risks

"Apparently, moderate coffee consumption doesn't cause harm. It actually seems to reduce the risk of gallstones, discourage colon cancer and reduce the risk of liver cancer," Gebo said.

Gebo said researchers are now investigating the possible effect coffee may have on heart disease. Java might even play a role in decreasing a person's risk for developing diabetes, though it doesn't benefit those who already have the disease.

Texas researchers indicate the correlation doesn't come from the caffeine, but it may relate to other complex organic compounds found in coffee.

"Some studies looking at coffee consumption and risk for coronary artery disease and diabetes suggest there may be a beneficial effect to drinking one to two cups of coffee a day," University of Maryland endocrinologist Dr. Nanette Steinle said.

Health experts said those at risk of heart illnesses should drink low amounts of caffeinated coffee, if any at all, because it can cause an increased heart rate.

Effects on young people

Steinle said young people are not immune to the effects of coffee. She said the central nervous systems of younger people can get over-activated, causing them to become shaky.

"Small doses can help improve concentration, but larger does can result in irritability and poor sleep. That can result in problems for young children's and teens' development, particularly in bone development and their neurological development," Steinle said.

Research has deemed small doses as one or two servings versus multiple servings.

Quitting coffee

Meanwhile, health experts recommend those who would like to quit ease off, gradually reducing caffeine intake over a couple weeks.

They suggest drinking a blend of half-decaf and half-caffeinated coffee and drinking less each day, before eventually substituting decaf or non-caffeinated products for regular coffee.

Juliano said that more than half of those who try to break up with ol' Joe fail.

"It does require some vigilance, coping, substitutions (just) as someone quitting cigarettes would need," Juliano said. "People interested in getting off caffeine don't like idea of a physical dependence. Others can enjoy coffee and it doesn't cause problems."

When asked whether he would consider giving up coffee, a business traveler in Hartford said, "How much money you got?"