Lighting is the single most important element in decorating, dramatically improving the look and feel of any room.
In addition to being functional, lighting can also influence the mood of a room, in three different ways.
First, the general illumination can strongly influence the mood of a room. A brightly lit room projects a positive, upbeat mood. A darker room is more intimate and romantic. One mistake many people make in lighting their homes is to have only one extreme or the other so much light that you need sunglasses or just a dim candle.
Second, the lighting fixtures themselves express a mood. Some fixtures are traditional some contemporary, some are lavish and ornate, some are starkly simple. As with the furniture you select, the style of the lighting fixtures should be suitable in mood to the rest of the décor.
Third, you can provide accents of light in specific parts of a room for no functional reason, but simply because they will add a dramatic touch.