Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Seasonal affective disorder, also known as seasonal depression, is a type of depression that affects an individual every year during the same season. Women are affected by seasonal affective disorder more often than men. According to medics, individuals living in areas with long winter nights are more likely to suffer from the disorder, however, there is a form of seasonal affective disorder which involves depression during the months of summer. Learn more about the mood disorder, its causes, symptoms and treatment in this book.