It seems that every house or apartment has at least one small room in it. This small space can be a spare bedroom or other. You can paint the room in a variety of light-colored shades. Pastel colors are most effective in creating a peaceful setting, while they increase the lightness of the room.
Dark colors make the room look smaller than it really is.
In fact, some colors can actually make the room feel like the walls are coming in on you, so avoid dark colors, or save them for large, spacious rooms. For the fullest effect of space, you should not paint the walls the same color as the ceiling. You could paint the walls a pastel color, but cover the ceiling in a clean white finish. The lighter the room, the bigger it appears to be. Or, for another broken-up effect, you could paint three of the walls using one pastel color, and then paint the fourth in a lighter or slightly darker shade of the same color.