Energy drink buzz: What’s in the potent liquids?

If mixing Red Bull and vodka seems like a way to imbibe while avoiding late-night drowsiness — well, it is, according to the headlines this week, but at a cost. College students who drank a cocktail of alcohol and energy drinks reported feeling twice as stimulated as those who drank alcohol alone, according to a new study from Northern Kentucky University.

The caffeine overrides the drowsiness that kicks in after drinking alcohol.

The danger here, says lead author Cecile Marczinksi, is that you don’t realize how drunk you’re getting. She tells Time Healthland:

“Stimulation may not be a good thing when you’re drinking because you may drink longer, decide to stay at a party where you’re drinking longer, and drink far more than you originally intended.”

The conclusion may not be surprising to college students, but the danger is on the radar of the Food and Drug Administration which sent warning letters in November to four makers of drinks combining alcohol and caffeine, including the drink Four Loko. The FDA cited studies — similar to this one — which suggest that caffeine suppresses alcohol’s natural sleep-inducing effects. People get drunk and act drunk, but report not feeling drunk.

But energy drinks have more than just caffeine. In Marczinski’s study, she found students felt more alert after they had consumed alcoholic energy drinks compared with drinks made just from caffeine powder. The combination of ingredients may be more stimulating than just straight-up caffeine, she says. Here’s a look inside a can of energy drink:

—Sugar. Glucose is found in most popular (non-diet) drinks. This is where the calories — i.e., actual energy — are.

—Caffeine, of course. A natural upper, too much caffeine can make you feel anxious.

—Guaranine. Derived from the guarana plant, guaranine is a caffeine-like stimulant.

—Taurine. This amino acid isn’t a stimulant like caffeine. Taurine is found in bile and regulates water and salt in the body. Taurine may be necessary for muscle functioning.

And of course you have gingko biloba and other herbs that may not have much of an effect in their small quantities.

What is clear, from this study and others, is the intoxicating yet stimulating effect of mixing alcohol with all these ingredients. Better watch the quantities.