In this article, the use of light therapy was shown to fight depression. I would suggest consideration of the possibility that the light therapy also increased the levels of vitamin D in these patients.

Patrick Albright
Cresson, Pa.

A review published last year by the Cochrane Library also found evidence that bright-light treatment is effective against depression. The review indicated that light treatment might be useful even for patients with serious nonseasonal depression.

Daniel F. Kripke
University of California, San Diego