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Seasonal Depression (SAD)

What Is Seasonal Affective Disorder (SAD, Seasonal Depression)?

Seasonal affective disorder (SAD) is a type of depression that is tied to seasons of the year. Historical facts about SAD include that as early as 400 BC, Hippocrates described changes in seasons as causing illness. Two hundred years later, light therapy was being recommended as treatment for people described as "lethargics" or suffering from "gloom." Most people with SAD are depressed only during the late fall and winter (sometimes called the "winter blues") and not during the spring or summer. That many cultures celebrate a number of holidays during the winter can be an additional stress for people with SAD. A small number of SAD sufferers, however, are depressed only during the late spring and summer. In contrast to SAD, other forms of recurrent depression, like bipolar or unipolar depression, occur independently of the time of year.

SAD is most common in young adult women, although it can affect men or women of any age. SAD affects people in both hemispheres an rarely within 30 degrees latitude of the equator. Some people may have a milder form of seasonal mood change.

Like all types of clinical depression, SAD can have a devastating effect on a person's life. Fortunately, almost all people with SAD can be helped with available therapies.

What Causes Seasonal Affective Disorder?

The exact causes of seasonal affective disorder (SAD) are unknown.

  • Chemical changes in the brain caused by changes in the amount of sunlight are probably involved. Risk factors for SAD include living in geographical locations that are dark or cloudy during the winter.
  • A tendency to have SAD may run in some families.
  • Given how often alcohol abuse and dependence occur in individuals with SAD, there is thought to be a possible genetic link between having either illness.
  • Low levels of vitamin D seem to be a risk factor for developing a number of mood disorders, including SAD.
Medically Reviewed by a Doctor on 11/18/2016

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Seasonal Depression (SAD) - Symptoms

What symptoms did you experience with your seasonal depression (SAD)?


If you have seasonal affective disorder(SAD), you will usually have symptoms of depressionduring the winter when there is less daylight (October through April). Symptoms of SAD include:

  • Difficulty concentrating.
  • Low energy and fatigue.
  • Reduced interest in daily activities, especially social activities.
  • Moodiness (depressed, sad, or unusually quiet).
  • Increased appetite.
  • Cravings for complex carbohydrates (such as pasta and bread).
  • Weight gain.
  • Increased sleep.
  • Loss of interest in sex.
  • Irritability.

People with SAD may either have symptoms of major depression or minor depression. Those with minor depression are considered to have subsyndromal SAD.


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