Light Therapy For Seasonal Affective Disorders
One of the most important applications of light therapy is in the treatment of Seasonal Affective Disorders (SAD). There is a large body of scientific evidence that points to the efficacy of light therapy for the treatment of SAD. What is not quite understood, yet, is how light treatment works.
We have shown that our daily rhythms are affected by the availability of the natural sun light. Many of us work in artificially lit buildings and does not get enough light. Most artificial lighting cannot replace the natural light. The reason for this is that the type of indoor lighting we use is not of sufficient intensity to affect the hormonal mechanisms which control our bodily rhythms. Intensity of light is measured in a unit called lux. One lumen means the light received by the receptor at an intensity of one lumen per square meter. Thus the intensity of light at any point is determined not only by the strength of the illumination source but also by how far it is from the source. The electric light used in most homes and workplaces rarely exceeds 500 lux. A sunny afternoon could be as much as 100,000 lux, and even the cloudiest day is rarely below 10,000 lux. Researchers have discovered that light of at least 2,500 lux is necessary to suppress melatonin production in humans. Most of the bright light therapy uses 5000 lux light (10,000 lux preferred.) The artificial light we use indoors is not of sufficient intensity to suppress melatonin and to correct the circadian rhythm. Night-shift workers, and people who live in Arctic climates, are usually exposed to light levels of only 50 lux. Light specialists believe this “mal-illumination” may be at the heart of many common disorders, including fatigue, depression, skin damage, suppressed immune function, and, of course, sleep problems. Continue Reading Article At LINK – Light Therapy For Seasonal Affective Disorder.