When you're painting a room, there are a lot of decisions to make. First, and perhaps the most daunting, is choosing a paint color. Then, you have to select the finish, a color for the trim, and decide if you want to paint the ceiling the same color as the walls. Because we tend to forget about the "fifth wall," that last question tends to trip up homeowners. To help you decide, we reached out to home decor experts for the pros and cons of painting the ceiling the same color as the walls. Here's their best ceiling-painting advice, depending upon the look you're hoping to achieve.

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If you're hoping to brighten up the room, New York-based interior designer Mikel Welch says that brushing the same color and finish on the walls and ceiling might not be the best choice. "For increased lighting in a dimly-lit room, opt for a shade lighter on the ceiling. As a general rule of thumb, I would go 20 percent lighter on the ceilings," he says. However, if the room is naturally sun-drenched, you can probably get away with the same color on the walls and ceiling.

"I always like to wrap a room in [the same] color," says Sarah Stacey, an interior designer based in Austin, Texas. That includes the ceiling: "Using a white ceiling with a bold wall color only detracts from a moody vibe," she explains.  If you're afraid of the room looking too dark, she seconds Welch's advice above, but recommends asking the paint store to add 50 percent white to the original paint color used on the walls. "Flat paint is so popular right now, so I would recommend going with just flat paint on both walls and ceilings."

Melinda O'Connor, an interior designer and architect based in Philadelphia, agrees. "In a more traditionally appointed room, it can be dramatic and moody to use the same color on both the walls and the ceiling," she says. "This looks best when the walls and ceiling are separated by a decorative crown molding, to be painted the same color as well. You can switch finishes up with a gloss for the crown and walls, or just the decorative crown. Just know that the higher gloss will show any blemishes on the surface."

If you want drama in the space, a high-contrast finish on the ceiling can help. Stacey recommends a lacquer finish to make the ceiling really shine. Again, since shinier paint finishes show off texture and imperfections, it is best left to smooth plaster ceilings.

"Always, always pay attention to your undertone when using more than one paint color in a room," warns Stacey. For example, if the walls are painted a warm terracotta color, you'll want to choose a white with warm undertones for the ceiling—otherwise the space will feel "off." If you're not confident about your ability to match undertones, opting for the same color on the walls and ceiling lets you skip the guesswork.

If you have an upstairs room or attic with angled or dormered ceilings, O'Connor says painting the walls and ceiling the same color is the way to go. "It can hide an uneven transition line at the slope and elongate the space while also making it feel very cozy," she says.

If the walls of the room are painted a shade of white, Southern California-based interior designer Anita Yokota swears by painting the walls and ceiling the same color. "Otherwise, the whites will contrast and it will look dingy," she warns. It's true, the right paint can actually make your home look cleaner.