Managing Seasonal Affective Disorder this Winter with Vitamin D Are you happier when it’s sunnier? If the answer is yes, there’s a reasonable explanation for why sunny days tend to make people happier. Sunlight is a natural source of Vitamin D, which our bodies need to maintain health. When the days are shorter and the weather is colder, many people suffer from Seasonal Affective Disorder (SAD), commonly referred to as seasonal depression. If ...