Many offices, mostly in places like Amsterdam, Paris etc. in art-deco building, take pride in the amount of natural light they're pumping in the office. With mirrors and sunroofs (with sails as shade) and a few plants, you can really give a beautiful, open air feeling to your office.

This, feels like crutches.

edit: there is something to be said about starting an hour earlier and finishing an hour earlier if the sunset is early. It may be a good idea to live with the natural rhythm of the earth rather than some clock on the wall.