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Seasonal Affective Disorder

Seasonal Affective Disorder

It’s that time of the year again when sunlight hours get short and Seasonal Affective Disorder starts to rear its ugly head. I hope this article will be timely and helpful.


Seasonal Affective Disorder, or SAD, is a mood disorder related to the shortening of sunlight hours during winter. It is more common in northern latitudes, in Finland for example. It is difficult to have an accurate estimate of actual prevalence in the U.S., but estimates range from 0 to 9.7%.


Symptoms of SAD are the same as those of depression, with the main symptom of depressed mood, plus additional common symptoms as described by the mnemonic SIGECAPS:

S: Sleep (decreased or increased)
I: Interest (decreased, also known as anhedonia)
G: Guilt (feeling worthless, hopeless, helpless)
E: Energy (decreased)
C: Concentration (decreased)
A: Appetite (decreased or increased)
P: Psychomotor retardation or activation (feeling slowed or feeling restless)
S: Suicidal thoughts

The unique aspect of SAD versus non-seasonal depression is that SAD regularly appears in the fall or winter, and SAD tends to disappear during spring and summer months, whereas non-seasonal depression has no correlation to the changing of seasons.


There is not currently a distinct diagnosis of “Seasonal Affective Disorder” in the DSM-IV. Psychiatrists diagnose SAD by adding a “Seasonal Pattern Specifier” to a Major Depressive Episode that appears as part of Major Depressive Disorder or Bipolar Type I or Type II Disorder. As with most mood disorders, SAD is diagnosed clinically, based on history. There is no blood test or imaging test that is diagnostic for SAD.


Treatment can involve psychotherapy, medications, light therapy, or combined treatment, depending on patient preference and severity of symptoms.

  • Psychotherapy: Cognitive Behavioral Therapy (CBT) has been shown to be effective for Seasonal Affective Disorder. Because SAD is a subtype of depression, I recommend the same workbook to my SAD patients that I recommend for my depressed patients – The Feeling Good Handbook by David D. Burns. Many patients find it helpful to go through the workbook and suggested exercises with the guidance of a mental health professional, though the workbook is made to be self-guided.
  • Medications: The most commonly used medications for treating Seasonal Affective Disorder are the same medications for non-seasonal depression: selective serotonin reuptake inhibitors (SSRI’s). These medications can be prescribed by your primary care doctor, or by your psychiatrist.
  • Light Therapy: Because the cause of Seasonal Affective Disorder appears related to the lack of sunlight exposure during fall/winter months, light therapy treatments have been developed. Most studies have focused on 10,000 lux light therapy for 30 minutes per day, given early in the morning. There are commercially available lightboxes and light visors that deliver this light in various forms. The key factors for effectiveness are intensity (lux) and duration. It is important to keep in mind that as you get farther from the light, the lux drops significantly. Most lightboxes require that you are within 12 inches of the light to deliver the recommended 10,000 lux. Important safety considerations are to make sure that you are not being exposed to UV light which can predispose you to skin cancer. Some boxes use special UV-free bulbs, others use a UV light filter to screen out UV rays. There is investigation into whether blue-light can be more effective than full-spectrum light. Another safety issue is that light therapy can cause patients with Bipolar Disorder to become manic or hypomanic. Thus, I recommend that light therapy be initiated and conducted under the supervision of a psychiatrist.
  • Combined Treatment: For some patients, the combination of psychotherapy, medications, and light therapy is the most effective form of treatment.

For Further Information

See the Wikipedia entry on SAD, a Mayo Clinic article on SAD, an article from the American Academy of Family Physicians, or contact a qualified mental health professional.

Article written 11/10/09 by Minyang Mao, M.D.

Disclaimer: This article is intended as an educational resource only, and is not intended to be a replacement for treatment. For evaluation and treatment, please contact a qualified mental health professional.

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