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Seasonal Affective Disorder (SAD) - Topic Overview

What is seasonal affective disorder (SAD)?

Seasonal affective disorder, or SAD, is a type of depression that affects a person during the same season each year. If you get depressed in the winter but feel much better in spring and summer, you may have SAD.

Anyone can get SAD, but it is more common in:

  • People who live in areas where winter days are very short or there are big changes in the amount of daylight in different seasons.
  • Women.
  • People between the ages of 15 and 55. The risk of getting SAD for the first time goes down as you age.
  • People who have a close relative with SAD.

What causes SAD?

Experts are not sure what causes SAD, but they think it may be caused by a lack of sunlight. Lack of light may upset your sleep-wake cycle and other circadian rhythms. And it may cause problems with a brain chemical called serotonin that affects mood.

What are the symptoms?

If you have SAD, you may:

  • Feel sad, grumpy, moody, or anxious.
  • Lose interest in your usual activities.
  • Eat more and crave carbohydrates, such as bread and pasta.
  • Gain weight.
  • Sleep more and feel drowsy during the daytime.

Symptoms come and go at about the same time each year. For most people with SAD, symptoms start in September or October and end in April or May.

How is SAD diagnosed?

It can sometimes be hard to tell the difference between nonseasonal depression and SAD, because many of the symptoms are the same. To diagnose SAD, your doctor will want to know if:

  • You have been depressed during the same season and have gotten better when the seasons changed for at least 2 years in a row.
  • You have symptoms that often occur with SAD, such as being very hungry (especially craving carbohydrates), gaining weight, and sleeping more than usual.
  • A close relative-a parent, brother, or sister-has had SAD.

How is it treated?

Doctors often prescribe light therapy to treat SAD. There are two types of light therapy:

  • Bright light treatment. For this treatment, you sit in front of a "light box" for half an hour or longer, usually in the morning.
  • Dawn simulation. For this treatment, a dim light goes on in the morning while you sleep, and it gets brighter over time, like a sunrise.

Light therapy works well for most people with SAD, and it is easy to use. You may start to feel better within a week or so after you start light therapy. But you need to stick with it and use it every day until the season changes. If you don't, your depression could come back.

Other treatments that may help include:

  • Antidepressants. These medicines can improve the balance of brain chemicals that affect mood.
  • Counseling. Some types of counseling, such as cognitive-behavioral therapy, can help you learn more about SAD and how to manage your symptoms.
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WebMD Medical Reference from Healthwise

Last Updated: July 07, 2010
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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