Seasonal affective disorder has a particularly apt acronym: In the fall andwinter months, lack of sunlight leaves those afflicted with SAD feeling gloomy, tired, and irritable. But their mood may not be all that suffers. Cognitive processes like memory may also be impaired--and these mental malfunctions seem resistant to light therapy, the main weapon against SAD.
Gail Eskes, Ph.D., and her colleagues at Canada's Dalhousie University found that SAD sufferers were less able to follow through on their everyday intentions and plans. Also impaired were visual memory and construction (visual memory helps us recall an object's location; visual construction lets us draw an object that we're viewing).