Stress can determine whether alcohol gives drinkers a jolt of energy or sends them sleepily off to bed, a new study reveals. The results of the study may provide a physiological explanation for why some people drink more when stressed, the researchers said. "When you give people alcohol in the lab, they tend to respond in one of two ways," said study co-author Emma Childs, who researches behavioral pharmacology at the University of Chicago. Drinking stimulates some people, making them feel "energized, excited, talkative, vigorous," she said. Others become "drowsy, unable to communicate," she said. But the study showed that when stress mixes with tippling, people can have the opposite of their usual reaction. Participants who said they normally derive a pleasant, stimulating buzz from alcohol reported feeling sedated when they were put in a stressful situation before drinking. And those who said they usually feel sedated after drinking instead became less drowsy, and had increased cravings for more alcohol when they were stressed before drinking. The study will be published this October in the journal Alcoholism: Clinical and Experimental Research. Don't try this at home The study's participants were 25 healthy men, most of whom were in their mid-20s and of European descent. The researchers put the participants into either a stressful or a non-stressful situation. The non-stressful situations included playing computer solitaire. The stressful situations included counting backwards aloud in multiples of 13 and speaking before a nonresponsive panel of interviewers. The interviewers are "very stony-faced. It's very disconcerting," Childs said. Each participant then received an intravenous drip of either alcohol (the equivalent of two to three beers) or a neutral saline solution. The researchers tracked heart rate, blood alcohol level, stress hormones and blood pressure levels while the participants answered a survey designed to measure their anxiety, calmness, and desire for more alcohol. This was the first study into the relationship between alcohol and stress that gave alcohol intravenously, Childs said. The method allowed the researchers to conceal from participants whether they were receiving alcohol or a placebo. When people know they're drinking alcohol, they may "expect to feel good or stimulated," Childs said. But because the participants never knew whether they were receiving alcohol, their responses were affected only by the neurological effects of alcohol, not merely the expectation of it. Under the influence… of stress The idea that stress changes the effects of alcohol may help explain why stress and alcoholism so often accompany each other, Childs told MyHealthNewsDaily. If stress diminishes the energy boost that some people normally associate with drinking, they "may actually drink more to feel that effect," she said. And people who are usually sedated by alcohol may also find themselves imbibing more in response to stress, because stress removes the unpleasant sedative effects of alcohol, which "are kind of a brake on drinking," she said. "If you have an acute stress, then at some point, you learn to come home and have a glass of wine or a drink — it becomes a learned response," Childs said. "It's going to increase your risk for stress-related disorders," including alcohol and drug addiction. Childs said she expected to see similar results in future studies, which will include women. "We tend to see the sedative and stimulation effect in women, the same as men. Their stress responses are very similar," she said. "I'm excited about this study,"" said Dr. Suzanne Thomas, an associate professor at the Medical University of South Carolina, who was not involved in the research. The study's small size was not concerning, she said. "Who is likely to experience alcohol as a rewarding drug after stress? The people who don't typically experience alcohol as a stimulant, but do experience it as a stimulant after stress," Thomas said. The new study also reported that alcohol dampens the body's normal hormonal response to stress. "Acute stress is kind of like an external threat to the organism. It's kind of like a challenge," Childs said. Unlike chronic stress, which is a condition that builds up over years, "the acute stress response is actually a beneficial thing," she said. "If you're going to alter that with alcohol, the body is not dealing efficiently with stress anymore." "Everybody thinks, 'Oh, alcohol, it helps me deal with stress,' but in actual fact it makes stress worse," Childs said. None of the participants were allowed to drive home after the study, she added. Pass it on: Drinking may affect you differently after a stressful day.