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Shedding Some Light on Seasonal Affective Disorder

By Joanna Shea O'Brien
Beth Israel Deaconess Medical Center Correspondent

person looking sadThough winter has yet to officially arrive, some may already be feeling the effects of Seasonal Affective Disorder, also known as SAD, a type of depression that is caused by reduced exposure to natural light. SAD's onset is usually in late fall to winter and can last through spring, although some people experience a form of SAD in the summer months. Populations farther from the equator at higher latitudes are more likely to be affected and there is a higher incidence of SAD in northern states, including here in New England.

Symptoms of SAD include a depressed mood, irritability, lethargy, fatigue, sleep disturbances, overeating, feeling discouraged, changes in weight and some difficulty in performing everyday tasks. Some people will experience all of these symptoms or only a few, and while SAD is a more serious condition than a fleeting feeling of "winter blues," anyone who has concerns should consult a doctor for diagnosis and treatment.

Although SAD is commonly understood as a winter condition, mid-fall is actually when the days become shorter and exposure to sunlight decreases. December 21 marks the darkest day of the year, with January and February days becoming increasingly lighter.

Dr. Michael C. Miller, a psychiatrist at Beth Israel Deaconess Medical Center and Editor in Chief of the Harvard Mental Health Letter, cautions that anyone who feels a low mood for more than a few weeks should consult with a doctor or seek a referral to see a mental health professional. He stresses that early detection and diagnosis is as important as anything because "the deeper you fall into a depressive state, the harder it is to get out without help."

Ideally, someone who has experienced SAD or thinks they may be vulnerable should consider treatment before winter arrives. However, January and February can be equally challenging, especially with New England snowstorms and frigid temperatures, and people being more inclined to stay inside and miss out on natural sunlight.

The good news is SAD is treatable. Light therapy and increased exposure to sunlight is one of the first lines of defense and can alleviate symptoms within a few days or a week. This includes taking a walk outside for 30 minutes during daylight hours or using a light box, which is different than a standard lamp.

Light can be measured in units called "lux," and while one could measure 50,000 to 100,000 lux on a sunny day, an indoor lit room only has a measure of about 200 lux. Using a light box can expose someone to 10,000 lux and doctors recommend using it first thing in the morning for up to 30 minutes.

"Some people suffering from SAD may experience a reduction in symptoms with the use of a light box, but oftentimes more serious cases require a combination of therapies including talk therapy, light therapy and antidepressants," says Dr. Miller.

"The bottom line is, if you have a low mood, take it seriously and don't dismiss it, particularly if it's persisted for a while," he adds. "These days, primary care physicians are very tuned in to psychiatric and/or mood problems and can be very helpful with treatment recommendations and referrals."

If simple things don't work, Dr. Miller advises patients to be persistent at exploring treatment options. Sometimes it takes several tries with different medications before a patient sees positive results.

To learn more about Seasonal Affective Disorder, click here.

Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.

Posted December 2011

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Department of Psychiatry
Beth Israel Deaconess Medical Center
330 Brookline Avenue
Boston, MA 02215

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Beth Israel Deaconess HealthCare
(Off-site Primary Care Practices)