One of the changes I made this month for Dress Your Walls was to paint the bedroom blue. It used to be a drab beige with a weird brown border along the bottom (this was pre-CasaSugar move-in), and it took two coats of low-VOC primer and two more coats of low-VOC paint to get the color right.
Cool colors, such as blue, brown, and grey, are thought to promote concentration and calmness. so they're great for bedrooms and offices. I know that I feel calm and happy whenever I walk into our new blue bedroom.