Seasonal Affective Disorder (SAD) are patterns of mood disorder that are directly associated with a specific time of year. This phenomenon is also commonly known as the "winter blues." People with SAD experience the same symptoms around the same time each year, with the fall and winter months being most common.
Winter/Fall SAD usually includes symptoms such as oversleeping, overeating, weight gain, irritability, and depression. Spring/Summer SAD, on the other hand, can often manifest quite differently with symptoms such as restlessness, poor appetite, weight loss, and mania.