Seasonal affective disorder

Alternative Names

Depression – winter; SAD

Definition of Seasonal affective disorder

Seasonal affective disorder (SAD) refers to episodes of depression that occur every year during fall or winter. Symptoms improve in spring and summer.

Causes, incidence, and risk factors

The disorder may begin in adolescence or early adulthood. Like other forms of depression, it occurs more often in women than in men.


Symptoms usually build up gradually in the late autumn and winter months.

Signs and tests

A visit to your health care provider will look for other causes of the symptoms and confirm the diagnosis. A psychological evaluation may be needed for more severe depression.


As with other types of depression, antidepressant medications and talk therapy can be effective.

Expectations (prognosis)

The outcome is good with continuous treatment, although some people have the disorder throughout their lives.


Fred K. Berger, MD, Addiction and Forensic Psychiatrist, Scripps Memorial Hospital, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. – 2/14/2010

Forms of depression

ADAM Medical Encyclopedia

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