There is no rule such that the bathroom lighting should be provided only in the ceiling or is better if it is provided at the sides or on top of the mirror. One has to fix the bathroom lightings according to one's taste and the mood that he or she wants to bring into the room. Even for a small bathroom, people, these days, go for two or more lighting fixtures. Thus, lighting is the most important factor to be considered in any modern bathrooms.
Layering and combining ; If you have no idea how to start the installation process, you might want to consider layering lights. This is the process of combining lights based on their purpose. The first thing you should do is choose a good task light. Task lighting fixtures can be ceiling downlights or wall sconces. These are great for interior design work that serves a specific purpose. You can place them close to the vanity counter or the mirror. Task lighting will make it easier for you to do a variety of tasks in the bathroom.
Bath lighting must meet three conditions: to be functional, aesthetic and to have a special ambiance. For the daily tasks (shaving, make up, etc.) you needed a strong light and for moments of relaxation, such as a bath in the tub, you need a discreet light. Also the bulbs that you use must provide the amount of light needed to properly light this room.
Natural light: In the event the style of your bathroom lets in a great deal of natural light, you should have only take into consideration illumination arrangements for after-dark hours. In other instances, you could have to use a mixture of natural and man-made light sources, or, even wholly man made sources to light up your bathroom. You can get a number of in halogen and standard incandescent lights available in the market. Choose the ones that are superb and bright and as close as possible to natural sunlight.