Seasonal Affective Disorder (SAD) is a type of depression that develops during the fall and winter seasons. You may notice a significant change in your mood and energy level when it gets darker sooner, and the weather turns chilly. You may also experience weight gain, little motivation to exercise, irritability, and relationship tension during the winter months.
Researchers believe that having less natural light may be the primary cause of SAD. Light therapy is one way to combat symptoms of SAD. Doctors recommend sitting in front of a "light box" or bright light treatment for a set amount of time, usually in the morning. You may have to use this treatment regularly until the spring. An antidepressant and exercise will also help improve your disposition.
Some final words of advice. Do things that you used to enjoy even if you do not feel like doing them. Do not make major life decisions when you're feeling depressed, and spend time outside even when it's cloudy.