Mixing alcohol with other substances is never really a good idea, and pairing it with energy drinks may be especially hazardous. That might seem obvious, but the results of a new study published in Alcoholism: Clinical & Experimental Research provide some interesting insights into why. Cecile Marczinski, a psychologist at Northern Kentucky University, found that combining energy drinks such as Red Bull with vodka or other liquors effectively removes any built-in checks your body has for overindulging. When you drink alcohol by itself, it initially induces a feeling of happiness — a comfortable buzz. But when you overindulge, your body knows it, and it starts to shut down; you start feeling tired, sleepy and more sedated than stimulated. "That's your cue to go home to bed," says Marczinski. But in her drinking study, for which she (easily) recruited participants, she found that people downing the combination of alcohol and energy drinks lost this natural control. Marczinski had volunteers show up at her lab and drink either plain alcoholic drinks; mixed beverages containing alcohol and energy drinks; energy drinks alone; or a non-alcoholic beverage. When the drinkers were asked to rate how stimulated and energetic they felt — whether they were alert or awake — those consuming the combination energy-alcohol drinks reported twice as much stimulation as those drinking alcohol alone. They tended to report less sedation and fewer symptoms like tiredness or sleepiness. "The disconnect between what you feel and how you act is what is the problem here," she says, noting that these participants continued to feel stimulated and never came down off their alcohol buzz. "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." Interestingly, Marczinski says, by combining these results with other work she has done on energy drinks, she found that it's not energy drinks' primary ingredient, caffeine, that's problematic. Rather, it's the mix of other awakening ingredients in the beverages that may be contributing to the enhanced alcohol high. When she compared the stimulation ratings between those who drank beverages made only from caffeine powder and those who drank alcoholic energy drinks, she found that the combination resulted in far greater alertness than the caffeine alone. "I always thought that it was a marketing thing when they mention the other things they put in like taurine, glucose and ginseng," she says. "But I think they do facilitate that stimulation; it's not just the caffeine." Marczinski was able to assess changes in behavior only 45 minutes after the participants enjoyed their drinks, so she didn't record any increase in impaired judgment or behavior, but, she says, that may be because the subjects weren't monitored long enough. Even so, the increased stimulation and impulsivity makes the combination of alcohol and energy drinks a dangerous one, especially for underage drinkers who may think they are capable of drinking more than their limit, or even driving after a party. "Even with just alcohol alone, young, underage drinkers are bad at deciding how safe a driver they are, but I think this would make that situation far worse," Marczinski says. And it's just another reminder not to drink and drive — no matter what combination of spirits you're consuming. Source: CNN