Seasonal affective disorder (SAD) is a type of depression with a recurring seasonal pattern, with symptoms most often starting in the late fall and early winter and going away in spring and summer. The risk of SAD is higher in people who live far from the equator and those with a personal or family history of depression. A variety of approaches have been used to try to manage SAD symptoms: 

• A type of cognitive behavioral therapy specifically adapted for SAD helps to relieve symptoms, and its effects may continue into subsequent years, even without additional sessions with a therapist. 
• Light therapy, which involves daily exposure to bright artificial light, had beneficial effects on SAD symptoms in several studies. The idea behind light therapy is to replace the diminished sunlight of the fall and winter months. 
• Even though people with SAD may have low levels of vitamin D, it’s unclear whether vitamin D supplementation can help to relieve SAD symptoms.