Blue Light Treatment vs Natural Sunshine

I have not seen any research comparing natural sunlight to blue light. The sun is incredibly bright, and sunscreens, even ones with UVA protection, don't block much visible blue-violet at 415nm (or else they would have a colored tint to them).

So the obvious question is whether Blue Light therapy is worth it for people who get more than a few minutes of natural daylight each day or whether its benefits are limited to people who do not get much natural sunlight.

While sun exposure has risks, assuming I am right about the relative intensity of the 420nm component of sunlight versus the treatment lights, we are talking about just a few minutes exposure a day, protected by sunscreen. (***- See correction/update below***)

***NOTE added 10/7/07*** After some research I am revising the relative intensities of sunlight versus the treatment lights - While sunlight is indeed extremely bright, its energy is spread across the entire color spectrum. The treatment lights, however, have all their energy concentrated in the violet wavelengths (~390-430) that kill the bacteria. So, while their total power is less, the power in the relevant wavelengths for the hi-power professional treatment light is actually more. My VERY rough estimate puts the high-power (40mw/cm2) lights at about 10-20x greater intensity in the critical violet wavelengths than natural sunshine. The home units, though, may be MUCH weaker than the professional units, so you still may do better in the sun than in front of a weaker blue/violet light source.

Since it's believed that the effects of light exposure are cumulative, 15 minutes in the sun should still help some (although getting a good dose depends on the light hitting the skin straight-on, not at a glancing angle).

Also, natural sun is strong in the red 660nm waves, which is claimed to help reduce inflamation.

Anyone know of any real scientific research on the topic? I would prefer studies not supported by equipment manufacturers.