According to researchers, about 15 per cent of the world's population suffer from migraine headaches, which are often amplified by light and associated with extreme light sensitivity. Many sufferers retreat to a darkened room until the acute attack is over. However, the researcher around Rami Burstein from the Harvard Medical School in his current study has shown that exposure to a narrow spectrum of green light reduces light sensitivity and headaches. The researchers have published their findings in the specialist magazine "Brain".
Link Between Sensitivity to Light and Migraines
More than 80 percent of migraine attacks are related to, and are being intensified by, light sensitivity, the researchers explain."Many migraine patients therefore seek the comfort of darkness and isolate themselves from work, family and everyday life," says Burstein. Although light sensitivity is usually less stressful than the headache itself, the inability to bear light can also severely limit those affected.
Even blind migraine patients react to blue light
Five years ago, the researchers had discovered the surprising discovery that blue light caused a reaction even in blind migraine patients. They said that the abnormal sensitivity to light in migraine patients could be alleviated by blockage of the blue light. They undertook further studies on patients who could not recognize all the colors of the light and "developed a way to study the effects of different colors of light on headaches in patients without visual impairment," reports Havard Medical School in a press release of the study results.
Pain in green light reduced by 20%
As part of their current study, Burstein and colleagues found that the condition of migraine patients worsened in all the colors of the light spectrum, except for a narrow spectrum of green light. With high intensity of light, such as in a well-lit office, nearly 80 percent of patients have complained about an intensification of headaches - in all colors except green, according to the Harvard Medical School. In low intensities, the special range of green light has even caused headache relief. The pain had declined by about 20 percent.
Different Signal Strength in the Brain
In order to understand the effect of green light in migraine patients, the researchers inspecific experiments, the strength of the electrical signals generated by the retina( in the eye) in the different colors and the response of the cerebral cortex( in the brain) to each color of the light. They found that blue and red lights produced the greatest amount of signals - both in the retina and in the cerebral cortex. On the other hand, green light has triggered the smallest signals. There were also differences in signal transmission in the thalamus. The neurons in the area of the brain, which carries the information about the light from the eye to the cortex, have responded most quickly to blue light and the slowest on green light, the researchers report. This could explain why migraine patients respond positively to green light.
Hope for therapeutic applications
The new findings "provide real hope for patients with migraine and a promising path for the future," stresses study leader Rami Burstein. The scientists are already working to develop a favorable incandescent bulb that emits "pure"( narrowband wavelength) green light at low intensity. Until now, the costs for a corresponding light bulb according to the researchers, however, are still prohibitively high. Even inexpensive sunglasses, which block the entire spectrum of light apart from the narrow range of pure green light, are already planned. But the technology of blocking anything but pure green light with a pair of sunglasses is only available in light microscopy, which is also very expensive. In the long term, the use of green light could be a very attractive method of treatment for migraine.(fp)