BEIJING, Jan. 11 (Xinhuanet) -- Scientists in Harvard Medical School have found the reasons why light can worsen migraine sufferers' pains, according to reports in Monday's  journal Nature Neuroscience on line.

    The scientists from Beth Israel Deaconess Center, an affiliate of Harvard Medical School, made an experiment by probing two groups of migraine-suffering blind individuals.

    Twenty blind people were divided into two groups, one totally blind and the other legally blind.

    The first group was unable to see images or to sense light and therefore could not maintain normal sleep-wake cycles. In the second group, although they were unable to perceive images, they could detect the presence of light.

    After studying these two groups of blind people who have migraine headaches, the researchers found out that light triggered a reaction in a group of brain neurons that remained active for some time.

    Nearly 85 percent of migraine sufferers are highly sensitive to light, a condition known as photophobia, but until no one understands why now, the reports said.

    (Agencies)