SEASONAL AFFECTIVE DISORDER
Seasonal affective disorder is a relatively newly recognized mental disorder. It shares many of the symptoms of major depression but it occurs during the winter months when sunlight levels decline. During the spring and summer, symptoms disappear. Typical symptoms are low energy levels, desire to sleep excessively, craving for sugar or carbohydrate foods, lack of sex drive, low self esteem, low mood, poor concentration, tension and irritability, and low tolerance of stress. Women are more likely than men to be affected. As many as 20 million Americans may be affected. The incidence of people with this problem increases in higher latitudes.
It is clear that the major cause of this brain disorder is lack of sunlight. Treatment with antidepressant drugs may be helpful but it obviously does not address the underlying cause. Therapy with full spectrum lighting has been shown to be effective in reducing symptoms. The current evidence is that morning exposure to a light box that puts out 10,000 lux (a unit of light intensity) for an hour daily is an effective dose. A fluorescent bulb that emits light as close to natural sunlight’s wavelengths is most effective. The best bulbs will have a Color Retention Index of close to 100 and a Correlated Color Temperature of 5500 K. Such bulbs come closest to replicating sunlight’s frequency distribution. The eyes must be open and receive the light directly to benefit. Looking straight at the bulb is not necessary. Some people may need two or more hours of exposure daily for best results.
Being outside and exposed to natural sunlight during the midday period will also provide benefit. Wintertime results in less formation of Vitamin D in the skin from ultraviolet ray exposure. Low levels of Vitamin D are associated with depression, as well as a variety of other health problems.
Sources of full spectrum bulbs and light boxes include www.mercola.com, www.fullspectrumsolutions.com, and www.naturallighting.com. If you think you have seasonal affective disorder, consult your health practitioner and discuss whether a trial of full spectrum lighting is appropriate for you.
Daniel Blodgett MD