White is the most common paint color for traditional ceilings, and it works just as well on a vaulted ceiling. The reason that white is such a popular ceiling color is because it gives the illusion of a higher ceiling. Since many vaulted ceilings begin at a lower point in the room than a conventional ceiling would, white paint will give the room a feeling of height. If your bedroom is particularly small, white is a good paint color choice because it will make the room feel more expansive. Start the white paint at the lowest point of the ceiling and paint everything below it a different color of your choice.
While white will make the ceiling appear higher, many people want a warmer color for their bedrooms. Get the effect of a white ceiling without the starkness by choosing a warm, neutral color for both the walls and the ceiling. Beige, off-white, cream, sage green and other light neutrals all work well with vaulted ceilings. Make the transition from wall to ceiling look seamless by painting them the same color and the monochromatic look will give a further illusion of height. Avoid using crown molding, as it will break up the line between the wall and the ceiling and make the ceiling look lower.
Not all bedrooms with vaulted ceilings are tucked into cramped attics. If your bedroom has high, cathedral-style vaulted ceilings, there is no need to create the illusion of height and you have more freedom in your paint choices. Choose whatever color matches the rest of your bedroom decor or makes you feel comfortable and cozy. Keep in mind, however, that the darker the color, the lower the ceiling will appear and you may lose some of the architectural drama of the high vaulted ceiling. If you don't want to commit to a dark color throughout the entire room, paint the walls the dark color of your choice, add crown molding painted one shade lighter and finish the ceiling in a color another shade lighter than the molding.
If you are painting your bedroom yourself, use painting tools that are appropriate for use on vaulted ceilings. The slopes of the ceiling can make ladders cumbersome and some corners difficult to reach. Invest in a good paint roller with an arm that extends and a pivoting head. If you're painting the ceiling a different color than the walls, tape carefully before painting, as the whole room will look sloppy if there is not a sharp definition between the ceiling and the walls.