A reader asks:

How does red and near-infrared therapy compare to bright light therapy for SAD?



Red light and near-infrared exposure to the skin may have some limited benefits in reducing pain and inflammation, relaxing muscles, and increasing blood supply due to vasodilation. However, these effects result from the heating of the skin and subdermal structures. This is in stark contrast to light receptors in the eye, which mediate antidepressant effects and coordination of circadian rhythms. The primary effect of infrared is the creation of heat. While there are trials underway, it currently cannot replace bright light therapy for SAD. Intense infrared exposure to the eyes poses a danger of heat burns. Although some “SAD lamps” may release energy in the red-to-infrared range, it is carefully minimized. Manufacturers of heat lamps advise wearing protective goggles.