Spend Time in the Sun! Sun boosts our mood, improves sleep, and promotes vitamin D production in the body. Many people suffer from seasonal affective disorder (a mild form of depression) during the winter months. Sunshine is good medicine. In fact, many mental health professionals prescribe a daily dose of sunlight to people with depression. Sunlight increases blood circulation and the production of white blood cells, which support the immune system and promote a good night’s sleep. Sunlight is also an excellent source Vitamin D, a key nutrient aiding in calcium absorption for strong bones and teeth.