Seasonal affective disorder


Seasonal affective disorder, often abbreviated as SAD, is a type of mood disorder that follows an annual pattern consistent with the seasons. The most common course for SAD includes an onset of depressive symptoms late in the fall, continuation of symptoms throughout winter, and remission of symptoms in the spring.


According to the handbook used by mental health professionals to diagnose mental disorders, the Diagnostic and Statistical Manual of Mental Disorders fourth edition text revised, or DSM-IV-TR , SAD is not considered a disorder or syndrome on its own. Instead, SAD is considered a pattern specifier, or subtype, of another mood disorder diagnosis . For example, an individual may be diagnosed as having a major depressive episode with a seasonal pattern.

The most common type of seasonal pattern is one in which an individual first experiences symptoms in the late fall, has continued and heightened symptoms in winter, and then experiences a remission of symptoms in the spring. However, other patterns are possible. For example, a person may become depressed in the summer and then become less depressed when the weather becomes colder.

Causes and symptoms


Lack of sunlight, normally associated with winter, is considered to be the primary cause of SAD. Although winter temperature may also have an impact, especially in colder areas, the lack of light is most important. This is supported by the effectiveness of therapy in which individuals are exposed to high-intensity light ( light therapy ). The causes of rarer types of seasonal symptoms, such as those experienced by individuals who become depressed in summer, are more difficult to determine.


The symptoms experienced by people with SAD are similar to some of those experienced by depressed people in general: change in appetite, weight gain or loss, fatigue , reduced energy, irritability, and avoidance of social situations. To meet the diagnostic criteria for the disorder as indicated in the DSM-IV-TR, these symptoms must be present during the season the individual is depressed and must lessen or abate when that season is over.


Some studies have shown that up to 6% of people experience some depressive symptoms in winter. SAD is a more common phenomenon in women than men. According to the DSM-IV-TR , women make up 60–90% of people with the seasonal pattern of depression. SAD primarily affects adults, although it is possible for children and adolescents to suffer from it. Research indicates that SAD is much more common in countries and regions where there are distinct seasonal changes. In countries near the equator, where changes in climate and light are mild, SAD generally does not occur.


SAD is diagnosed through a clinical interview with the patient and careful history-taking by the physician. For the seasonal pattern specifier to be applied to a DSM-IV-TR mood disorder diagnosis, the following criteria must be met: there is a relationship between the onset of the depressive episode and a particular time of year; the depressive symptoms are in remission at a particular time of year; the onset and remissions have occurred at these times for the past two years; and seasonal depressive episodes outnumber non-seasonal depressive episodes over the person's lifetime. Also, the seasonal pattern specifier must not be given when depressive symptoms are due to seasonally linked stressors, such as the beginning of school or an employment schedule.

An individual with seasonal depression must be distinguished from one with who has depressive symptoms all year long.


Light therapy, in which the person experiencing SAD is exposed to high-intensity light, is often used—usually for one to two hours per day. Sometimes, briefer periods of exposure to higher-intensity light can be used. The exposure to light may be facilitated through the use of a box which emits the prescribed light or through the use of a light visor the patient wears on his or her head. Tanning beds should not be used for light therapy. Light therapy has been found to be the most effective treatment for people correctly diagnosed with seasonal symptoms in the winter. It does not appear to have serious side effects.


Light therapy is considered to be a safe and effective treatment. However, it is time consuming and people do not always stay on the prescribed course of treatment. Also, SAD can be a persistent problem; even if light therapy is effective one year, symptoms may return the following year.

See also Bipolar disorders ;



American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revision. Washington, DC: American Psychiatric Association, 2000.

Salkovskis, Paul. Comprehensive Clinical Psychology Volume 6: Adults: Clinical Formulation and Treatment. Amsterdam: Elsevier, 1998.


Depression and Related Affective Disorders Association. 600 N. Wolfe St., Baltimore, MD, 21287. <> .

Seasonal Affective Disorder Association. PO Box 989, Steyning BN44 3HG, England. <> .

Ali Fahmy, Ph.D.

Also read article about Seasonal affective disorder from Wikipedia

User Contributions:

Sr. Dorothy
Depends on the geographical location as to when it occurs, too--in the Pacific Northwest, in addition to other symptoms, I am physically irritable (e.g. my glasses irritate my nose and ears) from about mid-August to's a long haul with all our cloudy weather!

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