zlacker

>>ivank+(OP)
A recent Cochrane review found very little high quality evidence in either direction:

http://www.cochrane.org/CD011269/DEPRESSN_light-therapy-prev...

It's not clear to me why light therapy is considered as a well-researched treatment.

>>sambe+Ad1
From the review, they found 2986 unique papers on the subject, they then assessed 91 papers from the 2986. From these 91, only 1 had a rigorous double blind testing but on only 46 people. The exposures for the light source was 2500 lux, IR light and no special treatment. The results were not significant.

So, lot-researched but maybe not well-enough researched.