Seasonal depression

As winter approaches and daylight hours grow shorter, some people noticed a significant change in their mood. It's called seasonal depression, or seasonal affective disorder (SAD), and experts say generally it occurs in the fall or winter. Research links the lack of light, which affects sleep patterns and chemical imbalances, can trigger the change in mood.

On Tuesday's "Focus @ 4," we'll explore other causes and effects of SAD, as well as ways to treat it.