The blue rays in the light sources used to treat SAD produce a non-zero risk to the retina (macular degeneration). By advancing the circadian cycle by wearing blue-blocking glasses in the early evening, the melatonin cycle may be made to finish before the individual awakens. With melatonin gone, the patient feels awake and not depressed.
University Heights, OH (PRweb) September 14, 2006. Exposing the eyes to light in the morning has become the standard treatment for SAD. Five years ago it was found that it is the blue rays that are most effective in suppressing melatonin and devices that only produce blue light are now available. It is still the blue rays from the white light sources that are producing the effect. This is not without some risk. The blue light is known to cause damage to the retina which ultimately may result in macular degeneration and partial blindness. The risk is small but not zero. Because this process is believed to be photochemical in nature rather than thermal, there is no completely safe level. In photochemical reactions each photon is capable of breaking a chemical bond and doing its damage. In thermal damage it requires many photons arriving at a certain rate to raise the temperature of the cells enough to cause permanent damage. The blue light damage is thus dependent on how many of the blue photons have arrived at the retina over a long period of time.
It is believed by some that the basic cause of SAD is the presence of melatonin in the blood which makes the individual feel sleepy and depressed. The successful treatment with blue light that causes suppression of melatonin supports this view.
This new treatment for SAD is completely free from the retinal hazard of blue light. It depends on advancing the melatonin cycle so that it finishes before the individual awakens. This is made possible by donning blue-blocking glasses in the early evening. After doing this regularly for several consecutive days, the melatonin cycle will be advanced in time.� Many studies have shown that the melatonin cycle will not last more than 9 or 10 hours even when no light is present to suppress it, e.g. blind people.� If the glasses are put on regularly at 9 P.M., the cycle will start by no later than 10 P.M. and finish no later than 8 A.M. If this is not early enough, the glasses may be put on at 8 P.M. to finish the cycle by 7 A.M. Since the glasses only block the blue light, the other colors of light are available for reading, watching television or working on a computer. Glasses that block the light causing melatonin suppression are available at www.lowbluelights.com.
In addition to being the sleep hormone, melatonin is also a powerful cancer fighter. Restoring the flow of melatonin to 9 or 10 hours from the 6 or 7 experienced by most Americans may provide more time for melatonin to destroy the beginnings of a tumor. Blind people with their 9-10 hour flow of melatonin have only half the risk for cancer.
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