What is seasonal affective disorder?

Seasonal affective disorder, or SAD, is a mood disorder characterized by depression related to a certain season of the year - especially winter. However, SAD is often not described as a separate mood disorder but as a "specifier," referring to the seasonal pattern of major depressive episodes that can occur within major depression and manic depression.

Who is affected by SAD?
Onset usually occurs during adulthood (with the average onset occurring at approximately age 23), and is four times more likely to affect women than men. Approximately 11 million people are diagnosed with this disorder.

What are the symptoms of seasonal affective disorder?
Two seasonal patterns of symptoms have been identified with SAD: a fall-onset type, also called "winter depression," in which major depressive episodes begin in the late fall to early winter months and remit during the summer months, and a spring-onset type, also called "summer depression," in which the severe depressive episode begins in late spring to early summer. The following are the most common symptoms of SAD.
However, each individual may experience symptoms differently. Symptoms may include:

increased sleep and daytime drowsiness
irritability
fatigue, or low energy level
decreased sex drive
diminished concentration
difficulty thinking clearly
increased appetite, especially for sweets and carbohydrates causing weight gain
The symptoms of SAD may resemble other psychiatric conditions. Always consult your physician for a diagnosis.

What causes SAD?
Decreased sunlight is thought to be part of the cause of SAD, and is under clinical investigation.

Treatment for seasonal affective disorder:
Specific treatment for SAD will be determined by your physician based on:

your age, overall health, and medical history
extent of the disease
your tolerance for specific medications, procedures, or therapies
expectations for the course of the disease
your opinion or preference
The treatments for "winter depression" and "summer depression" often differ, and may include any, or a combination, of the following:

light therapy
antidepressant medications
psychotherapy 

By Arthur Buchanan