In 2002, about 25% of 18- to 24-year-olds reported drinking coffee sometime within a two-week period. By 2012, the percentage of young adults drinking coffee in that same time frame hit 39%.

"It's an explosive growth in the consumption of coffee," says Harry Balzer of the NPD Group.

Recent studies link coffee consumption to a range of good health effects, including decreased risk of dementia and decreased risk of depression among women.

But experts say there is one downside that's often overlooked: Coffee consumption can get in the way of a good night's sleep.

"Our data has shown that a brewed coffee contains much more caffeine than a cold cola beverage" says Bruce Goldberger, a toxicologist at the University of Florida.

The Center for Science in the Public Interest took a look at several popular items and analyzed their caffeine content. It found that a 12oz. cup of coffee from Starbucks contains about 260mg of caffeine, which is about five times more than a 12oz. can of Diet Coke.

The caffeine content of coffee varies widely. McDonald's coffee, for instance, has about 100mg for a similar-size serving, which is significantly less than Starbucks. Dunkin' Donuts coffee is somewhere in the middle.