Nice bathroom
As far as I can see, you don't have a ceiling in your bathroom. Every room has a light source in its ceiling, maybe that would help.
In case you don't have it already, here you can find a library file with lights in several strengths and colours.
Also, keep in mind that the renderers can't handle light falling through glass (or at least have difficulty doing so), and that the colour of the sky has a strong impact on the quantity of light in your model.
Hans