Is it seasonal depression or just the winter blues?

Even if you're not clinically depressed, a little light can counter sleepiness, low energy, and carbohydrate cravings.

The dark nights are longer these days, but they don't have to be dark nights of the soul. Although only 5% to 10% of the population has outright seasonal affective disorder (SAD)—marked by sadness, loss of interest in regular activities, exhaustion, and weight gain—about 25% of people living in the middle and northern regions of the United States get the winter doldrums—milder changes in mood, alertness, energy, and appetite. SAD requires professional treatment, but the winter doldrums can be more easily banished.