Generally the Recording Studios are closed and artificially lit so that the effect of the sound and music is effectively and completely captured, check http://www.parlourstudios.co.uk/. But it is very important to make space for some sunlight too. This will add glamour to the area and make the recording very natural. At such surroundings a song making can happen healthily and happily. Now-a-days with fast growing technology, artificial lights have started replacing sunlight effects.