How to ward off SAD with light therapy

You don't need full-spectrum lighting, which is light containing all the wavelengths, from ultraviolet (UV) to infrared. In fact, the UV is harmful to your skin and eyes. Choose broad-spectrum lights instead, which omit the UV and feature the healing green wavelength. (This eliminates the need to apply sunscreen.) The light looks white, however, because it also contains yellow, red, and blue. Most natural products stores and hardware stores carry broad-spectrum lights. You can also find them on the Internet.

The intensity of the light is what counts. Go for 10,000 lux (a standard measurement of light intensity) from a light box, or install four 2,500-lux bulbs in existing fixtures in the room where you spend early-morning time. Choose fluorescent bulbs, which diffuse the light safely, rather than incandescent bulbs, whose light comes from a small source, such as a filament, and which do not shine brightly enough beyond a distance of 12 inches.

You can use compact fluorescent bulbs that screw into normal light sockets. These retail for about $50 per bulb. However, they use 80 percent less electricity than a typical bulb and last 10,000 hours, which is about 10 years of average use.

Bulbs or your portable light box need to be 2 to 5 feet away from your skin, which means ceiling lights are not particularly effective. A nice way to use your light box is to plug it into an electric timer and orient it toward your bed so it turns on automatically in the morning.

—E.A.K.