When we think of the effects of light, we usually think of the influence it has on our visual senses, our mood, or our skin. Too much—and too little—can spark an array of reactions, affecting everything from sleep quality to task performance. But, it turns out, light also has the ability to change our perceptions when it comes to taste.

For a 2009 study, researchers separated groups of wine drinkers, arranging them in rooms lit with red, blue, green, or yellow fluorescent lights. The subjects were then asked to sip wine and report on their impressions. Surprisingly, those bathed in red ambient light said the wine was sweeter, richer, and generally more satisfying than wine ingested in other rooms—and that they’d even be willing to pay more for it.

It turns out all of the study participants were drinking the exact same wine—the light hadn’t changed a thing besides the appearance of the liquid in their glasses. Under red light, it’s possible that the wine appeared darker and richer, creating a corresponding expectation in the minds of the subjects.

Light can also have the opposite effect: Psychologists have noted that appetites under blue lights appear to shrink, with blue-tinged foods becoming less appealing due to their appearance. In other studies focused on light and how we perceive taste, some people were shown to be attracted to stronger flavors under brighter lights, and more subdued foods when the light is dim.

One theory is that our senses are trying to maintain a balance. If you don’t feel like having something sweet in a dimly-lit restaurant, that might be one reason why. And if you want to be serious about your wine-tasting, there might be something more important than a bottle opener: a neutrally-lit room.