If you're not sleeping well, it could be time to repaint your bedroom. A study by the Travelodge motel chain reveals the color of your bedroom walls may help you sleep better. The study says blue walls can make you feel restful and calm because they remind you of the sea and sky. Yellow walls are conducive to happiness, as long as they are not too bright. Green walls can put you at ease because they remind us of nature. The study says bad colors for sleep include purple, which may cause nightmares, and red, which is too exciting. Gray walls can make you feel isolated. Brown is also a depressing color, but the study says brown is the favorite bedroom color of workaholics.