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Seasonal Affective Disorder

Woman checking her phone on a cold winter night.

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." This refers to the seasonal pattern of major depressive episodes that can occur within major depression and manic depression.

SAD is a clinical diagnosis accepted in the medical community. Norman E. Rosenthal, M.D. is the researcher credited with discovering SAD.

Five Facts About Depression

  • Depression is different from feeling sad or unhappy. It is not a sign of personal weakness or a condition that can be willed or wished away.

  • During any one-year period, nearly 21 million American adults can suffer from depressive illness.

  • Women experience depression about twice as often as men.

  • Without treatment, depression can last weeks, months or years, but most people respond well to medication, therapy or a combination of the two.

  • Most people with clinical depression who seek treatment see improvement, usually within weeks.

Who is affected by SAD?

Onset usually occurs during adulthood (with the average onset occurring at approximately age 23), and is more likely to affect women than men. According to the National Mental Health Disorders Association, approximately 10 to 20 percent of the population suffers from mild winter SAD, and nearly 5 percent suffer from a more severe form of the disorder.

What are the symptoms of SAD?

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 see your health care provider for a diagnosis.

What causes SAD?

Pedestrians walking along a busy street during the winter.

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

How is SAD treated?

Specific treatment for SAD will be determined by your health care provider 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, such as cognitive behavioral therapy or interpersonal therapy

Depression and Sleep: Understanding the Connection

Forlorn woman

Depression and insomnia often go hand in hand. Know the connection between the two, and learn how to recognize symptoms and get treatment for both.

Read more.




Depression: What You Need to Know as You Age

Older man

Get the help you or a loved one needs, and learn the latest expert insights on coping and preventing this mood disorder.

Read more.




Seasonal Affective Disorder: What You Should Know

Woman with seasonal depression using a light box

The bright lights of the holiday season aren’t just for decoration: They can also help regulate your mood. Learn about SAD, which affects an estimated 10 to 20 percent of the population.

Read more.

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