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.
It is indicated that you should use lighting fixtures directed down with special ornaments or decorative pieces which help in reshaping the bathroom and obtaining a special effect. Sources of lighting must be fixed and directed so to have an efficient light and to focus on dark areas or objects that you want to put in a special light.
Remember that different kinds of bathroom designs require different kinds of lighting. The lighting you choose for your bathroom will be largely dependent on the room design, personal choice, as well as the bathroom setup. Make sure that the lighting in the bathroom is just right, not very bright and neither too him.
But the second aspect to consider when choosing your bathroom lights is safety. Clearly a bathroom is a wet area, and electricity and water are not the best of companions. Today however there's a very easy system in use which helps you to quickly and easily identify the type of light that's suitable for each area of your bathroom.