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Symptoms and Signs of Seasonal Depression (SAD)

Doctor's Notes on Seasonal Depression (SAD)

Seasonal Affective Disorder (SAD, Seasonal Depression) is a type of depression that is linked to the seasons of the year. The majority of people that have SAD have symptoms mainly in the late fall and winter seasons (a few have summer SAD) and is most common in young adult women. Signs and symptoms may include depressed mood, fatigue, loss of interest in activities, feelings of worthlessness or hopelessness, poor concentration, indecisive and thoughts of death or suicide. These occur at about the same time each year for the individual; some experience anxiety anticipating the seasonal changes and their returning symptoms. People with winter SAD may also exhibit excess sleeping, craving for sugar, starchy foods or alcohol, weight gain, heaviness in arms and legs, have social conflicts and behavioral changes. Other signs and symptoms of summer SAD include insomnia, poor appetite, weight loss, agitation and anxiety.

The exact causes of SAD are unknown. However, SAD may run in families and may be related to alcohol abuse, and low levels of vitamin D. Some researchers believe chemical changes occur in the brain when sunlight is reduced or increased as seasons change.

Medical Author:
Medically Reviewed on 3/11/2019


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.