We all have natural reactions to color—a clear blue sky can make you feel more peaceful; a bunch of daffodils, more optimistic. So its no surprise that the colors in your home can have an impact on your mood, too. Red, for instance, tends to be stimulating, and blue, calming, says color researcher Nancy J. Stone, PhD, a professor of psychology at Creighton University. How pure and bright a shade is can come into play, too, as well as personal associations with the color. Heres how you can tap into the power of color to feel happier, calmer, or more inspired—without a huge paint job.