Seasonal affective disorder SAD is a type of depression that occurs at the same time each year. SAD most often begins in the fall or winter and then subsides in the spring. It sometimes is called the "winter blues" because most people with seasonal affective disorder have an episode of depression during the winter months, although it is possible to experience SAD during summer months. A diagnosis of SAD is made when a pattern of depression and remission from depression is present for at least two consecutive years.
What are the symptoms of SAD?
SAD consists of four central features:
Recurring major depressive episodes that begin around the same time each year (usually in September or October) and end around the same time each year (usually in April or May)
Full recovery from the symptoms during "nonseasonal" months (usually May through August)
Depressive episodes that occur during the same time of year for two consecutive years
Over the lifetime course of the illness, more depressive episodes during winter months than summer months
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