Something I don't think has been mentioned on this thread: it isn't the intensity or spectrum of the light that has the most influence on its effectiveness, it's the timing. Needs to be first thing in the morning - about the time of summer sunrise.

And remember a small light close to you is just as effective as a brighter one further away. Lighting up the whole room is just wasting power - it isn't your walls and carpet that are getting depressed.