Lighting

In our hallway, there is no outlet where we could plug in a night light. So for night lighting, we have the choice of leaving an overhead light on all night, or plugging in the xmas lights strung across the hallway.

Which do you suppose is more environmentally friendly; the overhead hall light, or the string of xmas lights?

I found some numbers which said that a 100 ft. string of mini lights (which is what I think I've got, although I'm not sure) uses 40 W. Anyone got a clue, and how clueful is your clue?

foomp. Dana go boom.