This involves exposing the eyes to daily periods of light in the form of a light box. While the standard for light boxes is full-spectrum florescent lighting, studies indicate intensity, rather than the type of light, determines the success rate. The light must be bright, at least five times brighter than a well-lit office, for example. During a session, the individual sits in front of the light box with lights on and eyes open. It's not necessary to look directly at the light.
Most people show improvements by using the light box in fifteen to thirty minute increments.
However, if you're symptoms are serious enough to require a light box, you should first seek advice from a physician. In all three cases, the experiments focused on which time of day was best for light therapy. Morning light, as opposed to evening, is believed to best counteract the symptoms of SAD, by advancing the whole cycle to an earlier time of day. In the studies, three quarters of SAD sufferers responded well to the morning light therapy. If you think you might have full-blown SAD, see your physician.