Let there be more light.

Let there be more light

In the last several years, researchers around the world have found that people who suffer from seasonal affective disorder (SAD), which throws them into a full-blown depressio during the same two or three months every winter, often feel better after sitting in front of bright lights. The light therapy consists of several hours of exposure each day for about a week.

There is room, however, for improvement in the treatment of winter depression, says psychologist Michael Terman of the New York State Psychiatric Institute in New York City. In a review of 30 recent light-therapy studies encompassing more than 300 SAD patients, he finds that just over half of those treated with bright lights in the morning fully recover from their depression. The recovery rate dropts to about one-third for those given light therapy at midday or in the evening.

While morning sessions are the most successful, it may be more effective to use light far exceeding the standard intensity employed by researchers, says Terman. The most common procedure is to place in individual in front of a screen emitting light five times brigher than ordinary room light.

This past winter Terman treated 18 SAD patients with light 20 times brighter than normal room light. This light exposure lasted for 30 minutes in the morning. A high-intensity screen that emitted the light was placed at an angle above each patient's head in order to simulate outdoor natural light just after sunrise. All the patients improved substantially, he reports, usually within several days of treatment.

"We need to see if longer periods of exposure to standard-intensity bright lights have stronger effects," says Terman, "as well as developing more naturalistic light sources."

Computer-controlled light screens are now under development that are placed in a patient's bedroom to automatically simulate the natural light of a sunrise during the dark mornings of winter, he notes.