Too often lighting a bathroom is low on the list of priorities relative to other rooms in the house. But with bathrooms becoming larger and more elaborate, proper lighting is essential to making the most of the space.

Your bath should be bright and clean.
Ample overhead and task lighting are key. But bathrooms are now a room in the house where people are spending a lot more time, so you’ll also want the ability to create an atmosphere that’s relaxing and spa–like. Having flexibility to adjust the lighting is really important, which is why you should add dimmers here just like you do throughout the house.

Start With the Ceiling and Vanity Light, Then Work Your Way Down
First, ceiling–mounted or recessed lighting overhead for general illumination. You’ll also want to light the vanity area with some excellent task lighting, which can be a fixture above the mirror or sconces on either side. And you need to light the shower and tub area. You might also consider strip lighting under wall–mounted cabinets, which makes them appear to float in space, as well as illumination for wall art.

Don’t Overdo It, But Don’t Under-Do It Either
People often have a tendency to pop a dozen can lights into the ceiling to make sure the bathroom is bright enough, but then you end up with a ceiling that looks like Swiss cheese. Everything in moderation. Though, don’t make the mistake of under-lighting your bathroom, because ample lighting is important. Another reason dimmers are key.

Source: ylighting.com