Dark mornings. Days with gray skies. Evenings when the sun sets before the workday has even ended. Spring is weeks away, but we could all surely still stand a serious jolt of color to help give our spirits a big boost right now. Color theory (i.e., using colors to influence our moods and behavior) is a fairly new discipline, and there’s good research to show that it can help reduce stress, improve sleep, and can change your mood. Color theory su…