Despite caffeine’s shaky reputation in the past, there’s more and more convincing evidence that it’s not only not so bad for us, but in some ways, may actually be quite good for us. It’s the most popular neurostimulant in the world (of the legal ones, anyway), according the authors of a new study that uses brain imaging to look at how caffeine exerts its wondrous effects on the brain. And that description isn’t total hyperbole – previous research has shown caffeine to reduce the risk of neurodegenerative diseases like Alzheimer’s and Parkinson’s. The new study gives us some of the first clues in humans as to why this may be.

Adenosine receptors are found throughout the brain and body. In the brain, adenosine builds up throughout the day, ultimately making us feel tired by the end of it. But caffeine is a brilliant adenosine mimic – so, taking the place of adenosine, it blocks those receptors and keeps us feeling chipper and alert.

In very high doses, of course, caffeine is not so good for you, and, in the form of energy drinks, has recently been the subject of some serious concern. But if you’re in the “moderate” use group, you may be OK to continue your habit, if you’re not experiencing any unwanted side effects. In fact, it may be a very smart move for your brain.