Caffeine makes you more open-minded to viewpoints that contradict your own
You know that caffeine wakes you up. Some people can't make it through the morning without their daily cup (or two, or three) of coffee. It turns out that coffee does more than that though. It may make you more amenable to persuasion.
Researches have found that caffeine primes the brain to agree with statements that it typically does not support because it improves the brain's ability to understand the logic behind these arguments.
So this happens because the brain is revved up not because caffeine generally boosts your mood. Researchers also found that the more distracted the caffeinated subjects were, the less likely they were to alter their views because they weren't focusing on the argument.