Lighting up the lives of the depressed.

For most of us, winter is a time of slowed activity; the shorter daylight and extended indoor periods can be, well, "depressing." But for some people, psychiatrists have documented, the winter brings true, clinical depression. Such persons experience depressed feelings; they oversleep, overeat and generally slow down significantly.

Preliminary studies have indicated that "Winter depression" may be helped by artificially extending light periods each day. Now, in a study in the February AMERICAN JOURNAL OF PSYCHIATRY, researchers from the National Institute of Mental Health (NIMH) in Bethesda, Md., report that bright has "a marked antidepressant effect." The scientists further suggest that the therapeutic mechanism may involve the altering of two brain neurotransmitter chemicals: melatonin and serotonin.

Norman E. Rosenthal and his NIMH colleagues treated 13 patients (6 of whom were hospital impatients) with both bright and dim lights in the morning and evening and with various combinations of the two. The control treatment involved sleep deprivation, which has been effective in other depression studies.

The researchers found that in 10 of the patients bright light--several times brighter than ordinary room light -- "caused a marked improvement in mood which was seen within a few days and lasted throughout the week of treatment. Removal of the light regularly caused relapse within a few days." The bright light was superior to the dim light in reducing depression. In a follow-up study, evening light alone was also effective.

On the basis of previous animal studies, the scientists suggest that bright

light somehow suppresses melatonin, which along with serotonin has been implicated in the onset of depression. "Light," they conclude, "may be an important element in the treatment of such patients [with winter depression] and a valuable key to understanding their condition."