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Seasonal Affective Disorder (SAD) Print E-mail
by Ron Kennedy, M.D., Santa Rosa, CA

Dr. Kennedy The term seasonal affective disorder (or SAD) is used to describe a disorder marked by depression during October through March in the northern hemisphere and April through September in the southern hemisphere corresponding to increasing duration of dark hours. People with classical SAD have a normal mood during the spring and summer.

The common symptoms of SAD are extreme fatigue and lack of energy, increased need for sleep and sleeping much more than usual, craving for carbohydrates and  increased appetite with weight gain.

From a geographic standpoint, the incidence of SAD increases as you approach the poles of the earth. This is apparently due to the decreasing exposure to sunlight in these regions during the winter. In Florida the incidence of SAD is about 1%, whereas in Alaska it is closer to 10%.

The mechanism by which light deprivation is thought to precipitate depression is by shutting down hormone production in the hypothalamic-pituitary axis although much more study is required before this can be stated with precision.Also, changes in brain chemical (neurotransmitter) function, particularly serotonin and dopamine, may be disturbed, and these neurotransmitter imbalances are corrected by light therapy. Patients with SAD may have reduced retinal light sensitivity in the winter that is corrected by light therapy. What we do know is that most people with SAD respond to light therapy.

Light Therapy

In the early 1980s Dr. Norman Rosenthal and colleagues at NIMH (National Institute of Mental Health) first described SAD and by the early 1990s had come to the conclusion that it was primarily due to light deprivation. This can, of course, be compensated for with the use of full spectrum lighting during the fall and winter months.

Two standard intensities are used in treatment. 2,500 lux for an average of two hours and 10,000 for an average of 30 minutes. Intensity can be varied by moving towards or away from the light. Improvement is usually observed within four or five days, if not sooner, and symptoms usually return in about the same amount of time when the lights are withdrawn. Most users maintain a consistent daily schedule beginning, as needed, in fall or winter and continuing until spring, when outdoor light becomes sufficient to return normal mood and energy. Some people can skip treatment for between one to three days without effect, but most notice the effects almost immediately if treatment is interrupted.

Light therapy is also called phototherapy. As little as 30 minutes per day of sitting under a light box results in significant improvement in 60-80% of SAD patients. Side effects are mild, although people with certain medical conditions or taking certain medications should avoid light therapy. Other adjunctive treatments for depression, including tryptophan or 5-hydroxy-tryptophan, may also be helpful for patients with SAD.

What  To  Do  If  You  Are  Depressed

Of all illnesses, depression is most especially one for which you should seek help. It is almost impossible to be objective about evaluating and treating your own depression, due to the nature of the illness. If you feel depressed more often than "rarely," I urge you to go for an evaluation as soon as possible. When you are ill with depression it is easy to miss the diagnosis altogether and think of yourself as an unworthy, or unlucky person. If you notice sleep, appetite, or mood disturbance, or if you are thinking self-destructive or suicidal thoughts, do not delay; seek help immediately.

The information in this article is not meant to be medical advice.�Treatment for a medical condition should come at the recommendation of your personal physician.

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