It's a phenomenon sweeping college campuses, and there are even Web sites dedicated to rating the various combinations.
Dr. Mary Claire O'Brien, an emergency room physician and associate professor of emergency medicine at Wake Forest University Baptist Medical Center in Winston-Salem, N.C., is lead author of the study.
On The Early Show Wednesday, she explained to co-anchor Julie Chen that drinking alcoholic beverages and energy drinks at the same time can in essence delay the perceived effects of the alcohol, misleading people into thinking they're not as affected by it as they really are, in turn endangering their bodies and making risky behavior more likely.
The study included some 4,000 college students from 10 schools.
O'Brien told Chen, "What we know from speaking with college students and from looking at Web sites is that they add energy drinks to alcohol in order to be able to drink more alcohol without passing out, and to party longer. ... I think what they want to do is drink more. That's what our research suggests.
"There is a buzz associated with the high dose of caffeine and the alcohol. One of the medical problems that occurs immediately after that, as the caffeine wears off, the big dose of alcohol kicks in."
"In our study, one in four college drinkers is mixing alcohol with energy drinks. ... We found that they did it in order to be able to drink more without passing out. Indeed, there is a much greater incidence of drunkenness and a much greater incidence of heavy episodic drinking when students mix alcohol with energy drinks.
"But, the real thing we were interested in was the association with serious, alcohol-related consequences, like riding with a drunken driver or being hurt or injured or needing medical treatment. And indeed, all those things were twice as likely among students who mixed alcohol with energy drinks."
O'Brien recalled taking care of a student "a couple years ago who drank enough alcohol mixed with energy drinks to basically be comatose when he arrived in the emergency department.
"And I think it's important to understand why I'm passionate about this subject. I'm a practicing emergency physician. For 20 years, I've been taking care of critically ill and injured patients -- 2.8 million college students drive drunk every year, and a good number of them end up in my emergency department.
"One of the things I have to do for a living is walk into the room and tell the parents that the student's never coming home again, and I'm a mom, so I'm pretty worked up about alcohol-related injuries."