A reader asks:

 I suffer from SAD and was wondering if UV light (from a sunbed) has any benefits?


As best we know, the mechanism of action of light therapy for Seasonal Affective Disorder (SAD) is through visible (not UV) light to the retina of the eye (not the skin). Addition or subtraction of UV light using standard light boxes makes no difference in the antidepressant effect. Beyond this, cumulative UV exposure to the eyes or the skin presents well-known health hazards, and thus it should be avoided when seeking relief from SAD. Indeed, it is important to ascertain that any light box used for SAD treatment maximally filters out UV (and there are several on the market that fail to do so).