Ever feel like you'd just die if you didn't have that daily cup of joe? Well, a recent study suggests coffee might, in fact, help you live longer. Researchers found that those who consumed three to five cups of coffee per day had a 15 percent lower risk of premature death due to causes ranging from diabetes to heart disease than those who skipped a daily cup. And while the study only shows that there's an association -- rather than definitive proof -- between drinking coffee and evading premature death, we can confirm that coffee consumption makes us feel invincible on a daily basis.

If you're on the shy side, it turns out you might not jive with java. In his book, "Me, Myself, and Us: The Science of Personality and the Art of Well-Being," author Brian Little says caffeine may negatively affect an introvert's productivity after their morning trip to Starbucks.

"After ingesting about two cups of coffee, extraverts carry out tasks more efficiently, whereas introverts perform less well," he writes. "This deficit is magnified if the task they are engaging in is quantitative [think: math] and if it is done under time pressure." The thinking behind the theory is that introverts, who tend to operate at an optimal level of alertness, are over stimulated by caffeine consumption, making them more distracted and less likely to perform well when tackling tasks. But, hey, introverts have still got good ol' booze when it comes to overcoming their inhibitions, so there's that.

No surprise here. Just one cup of coffee takes us from zombie to superhero all before we've finished checking our morning email. But how exactly does caffeine do that, and why does it work so quickly? For starters, it easily bypasses the blood-brain barrier, the central nervous system's built-in barricade to foreign substances. This filter blocks bacteria, viruses and most drugs from entering the brain. But coffee slips through unimpeded. Within 30 minutes, caffeine has infiltrated the bloodstream and every cell in the body. Consider it the Navy SEAL of substances.

Once it's crossed that barrier, it blocks the activity of adenosine, a neurotransmitter that plays a role in making us tired, explains Marci Clow, MS, registered dietician and senior nutritionist for Rainbow Light supplements. "By blocking adenosine other neurotransmitters, we become more alert," she says. "Studies have found that the caffeine equivalent of about two cups of coffee can enhance cognitive function and mood among sleep-deprived people, and affect the specific areas of the brain responsible for memory and concentration."

All of which is good news for those of us wishing to continue our coffee addiction. Bottoms up!

A good follow-up to that "but first, coffee" mantra that many of us subscribe to could be "and then poop." Yep, if you're among the many who refuse to consume coffee unless there's a toilet nearby, then you know caffeine may make you poop almost as immediately as you consume it. "Coffee promotes peristalsis, which is the contraction and relaxation of the intestinal muscles," says Clow about this curious coffee-poop correlation. "For some people, the bowel-stimulating effect of coffee is a way of keeping regular."

However, since many of us drink our coffee first thing in the morning, a post-coffee poop could also mean your gastrointestinal system is simply revving up at the start of the day -- and coffee is providing a little push of sorts. "Drinking hot water (separate from the coffee beans or added caffeine) also has a stimulating effect," says Nora Zorich, MD, PhD and Chair, Arbonne Scientific Advisory Board. "In this sense, having a bowel movement after the morning coffee is also likely related to other drinking (such as drinking hot water) or eating, which stimulates intestinal contraction waves." But we'll stick with coffee over hot water, thanks, since it gets both our bowels and our minds going in the morning.

You know how you'd rather douse someone with scalding-hot coffee rather than speak to them before having those first few sips of sweet, sweet brew? But once you're caffeinated, you're all ears? That could be because coffee is just as likely to boost mood as it is alertness. "In addition to blocking adenosine receptors, caffeine also affects other major neurotransmitters, including dopamine, acetylcholine and serotonin, delivering a boost even when we are well-rested," says Clow. "Dopamine improves mood, while serotonin makes us more relaxed, alert and energetic." The result is a feel-good rush from out morning coffee -- and useful information to those poor unfortunate souls who have ever dared to interact with us before we've had our first cup.