Seasonal Affective Disorder
What Is Seasonal Affective Disorder, or SAD?
What are the links between light and seasonal depression? Seasonal affective disorder (SAD) is a specific type of recurring depressive illness that manifests in an annual pattern. Usually, it begins in early to late fall. It lasts throughout the winter. It only subsides with the longer, sunnier days of spring.
Some people have a milder form of seasonal affective disorder known as subsyndromal-SAD (S-SAD). This mild form is also called the winter blues. This mild “winter blues” form causes minor problems in people’s lives but not the total disruption that full-blown SAD causes.
Subsyndromal-SAD, as well as the disorder most people simply call seasonal affective disorder, or SAD, are actually both classified as a disorder called Winter-SAD. This is because this disorder occurs in winter and in the months surrounding winter.
But Winter-SAD is not the only subtype of seasonal affective disorder. Another subtype is Summer-SAD. As its name suggests, this subtype of SAD occurs in the spring and summer months. Summer-SAD is much rarer than Winter-SAD. It is less well researched, and its cause is undetermined.Throughout this website, unless otherwise noted, the term “SAD” refers specifically to Winter-SAD. The two subtypes of seasonal affective disorder share a distinct link, however, between changes in natural light and seasonal depression that can be severe or mild.