Colors change our daily life. They can increase energy, eat well, and get promoted.First,  blue is the easiest for the eye to process. Second, red can enhance our appetite because our body produces a chemical called adrenalines when we see red. For contrast, blue reduces the appetite because so few blue foods exist in nature. Third, stores use yellow to indicate sale items. Because yellow is the first color that our eye processes. But too much of yellow or red can make people irritable. So we use a little red in our wardrobe for work. In the USA, dark blue has historically been associated with power, responsibility, and respectability.