Vibrant yellow, bright and easily visible, is a great color to wear on dull, dark, or rainy days to add a little sunshine to your life. (It's also a good color to wear after dark if you're walking along busy streets.) The color projects love, light, warmth, and wealth, enhances communication, learning, mood, and energy level.
Generally, yellow combats gloom and fatigue. It opens up or brightens rooms, and pale tones are good choices for classrooms; warm tones good for play areas and living rooms. It's the most visible choice of background color for signs (with black lettering). People who wear yellow are perceived as sunny, intelligent, warm, and compatible. So wear gold (also in jewelry) or yellow when you're asking for a raise.
Read more: http://www.beliefnet.com/Health/Healthy-Living/How-Color-Can-Change-Your-Life.aspx?p=4#ixzz1CFY2xY8a