Seasonal Affective Disorder (SAD) is a form of depression that fluctuates with the seasons. It is most prevalent in areas of the world that receive little or no sunlight during the fall and winter seasons. The sun's rays and Vitamin D production from sunlight helps to keep our brain chemistry optimally balanced. When we don't get enough sunlight, serotonin and dopamine levels begin to fall. These are two critical neurotransmitters in the brain that keep our moods positive and healthy. Low levels of serotonin, dopamine and Vitamin D are some of the main causes of depression. Taking walks in the brief periods of winter sunshine is a great way to help boost your serotonin and Vitimin D levels. A walk of even ten minutes will help your body to produce enough Vitamin D for the day.