When the seasons shift from summer to fall, many people feel excited, refreshed and eager for a change. But for some people, the changing season can bring on unexpected feelings of despair that go well beyond the occasional "winter blues." At SIU Medicine, we want people to be aware of seasonal affective disorder, or SAD. If left untreated, this condition can make it extremely difficult for a person to function throughout the fall and winter months. Keep reading to learn more and discover how we can help you or a loved one who may be struggling. What is seasonal affective disorder (SAD)