Mark Frye, M.D.


How is seasonal affective disorder diagnosed and treated?


Seasonal affective disorder (SAD) is a type of depression that occurs during the winter months. Although exactly what causes SAD is unclear, researchers know that lack of light and the ensuing effect on the body's circadian rhythm seem to play a role. The condition is diagnosed by assessing a person's symptoms. A number of treatment options have been shown to be effective.

The body's circadian rhythm, or biological clock, helps regulate when you feel like you should be asleep and when you should be awake. The lower levels of sunlight in the winter and fall, particularly in regions that are far from the equator, can disturb this internal clock, upsetting sleep patterns and, in some people, leading to feelings of depression. The change in seasons can also disrupt the body's natural balance of the hormone melatonin, which plays a role in sleep patterns and mood. Lack of sunlight also may cause a drop in serotonin, a brain chemical that affects mood. When combined, these factors can lead to SAD.

No specific blood test, brain scan or other procedure can definitively diagnose SAD. Instead, the diagnosis is based on symptoms. Essentially, SAD involves symptoms similar to depression. Prominent symptoms include sleeping too much with increased appetite and weight gain. Additional symptoms may include sadness, anger or easy irritability; lack of interest in activities you usually enjoy; difficulty concentrating; significant fatigue; lack of energy; and, in some cases, feeling that life isn't worth living, or having suicidal thoughts.

Timing is the unique factor in a diagnosis of SAD that differentiates the condition from other types of major depression. People with SAD have symptoms mainly during the winter months and, for some, symptoms get worse as winter progresses. In addition, symptoms tend to abate or go away as the season changes to spring. So the condition is more than just feeling blue, sleeping in on the weekends, or having the doldrums during January. A person who has SAD experiences persistent, pervasive symptoms of depression during wintertime. People often seek treatment for SAD when they start noticing that symptoms like fatigue and lack of energy are adversely affecting their work, daily activities, or level of engagement with their families.

There are multiple options for treating SAD. The antidepressant medication bupropion (Wellbutrin) is approved by the U.S. Food and Drug Administration for the prevention of SAD. Bupropion can be very helpful for people who have a seasonal pattern of depression and know they're predisposed to developing the condition. Many people begin taking this medication in October or November and continue through the winter, with the goal of preventing SAD symptoms or, if symptoms occur, reducing their severity and duration.

Light box therapy has also been shown to be effective in SAD treatment. Light boxes emit a broad-spectrum of ultraviolet light. For many people with SAD, sitting in front of a light box is most helpful during the early morning hours because, in essence, it simulates dawn. Typically, people sit about five to six feet away, at an angle (i.e., not direct exposure) from the illuminated box for 20 to 25 minutes while reading the paper or having breakfast.

A variety of self-care steps have also been shown to be useful for people with SAD, such as going outside on sunny days. In the winter, particularly when snow is on the ground, clear days can be brilliantly bright. Exposure to that natural sunlight can help relieve SAD symptoms. Getting regular exercise, maintaining healthy sleep habits and a predictable sleep/wake cycle, eating a healthy diet and avoiding sugary foods are all smart strategies for combating SAD.

If you suspect you may have SAD, talk to your doctor about what you're experiencing. You don't have to just suffer through the winter. Helpful treatments are available.

Mark Frye, M.D., Psychiatry and Psychology, Mayo Clinic, Rochester, Minn.

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Health - Persistent, Pervasive Depression Symptoms During Winter Could Be SAD