Fight Seasonal Affective Disorder with Vitamin D Does sunshine cure seasonal depression? Seasonal Affective Disorder (SAD) is a condition, commonly referred to as seasonal depression, that strikes during the winter. Cold, short days cause a lot of people to stay indoors, preventing them from getting enough Vitamin D from sunlight. Get outside in Mooresville this winter at local spots like Lake Norman where you can go hiking, boating, or fishing with groups like Fish On ...