After an extensive study, it seems that scientists have managed to solve the mystery of why migraine suffers are unable to tolerate light.

Light, researchers say, tends to intensify migraine headaches because of the presence of a particular group of retina cells present at the back of the eye. These "photoreceptors" then send signals to the brain through the optic never which further stimulate migraine pain neurons.

Even a very small amount of light is enough to affect the pathway of the nerves, which, consequently, send suffers running for dark places.

The study, however, did discover that while people who are completely blinded by eye problems like retinal cancer and glaucoma are not affected by light during migraine attacks, those who are "legally blind", i.e., have badly impaired vision and cannot make out images but detect the presence of light, are affected.

"While the patients in the first group did not experience any worsening of their headaches from light exposure, the patients in the second group clearly described intensified pain when they were exposed to light, in particular blue or grey wavelengths", said Professor Rami Burstein, from the Beth Israel Deaconess Medical Centre in Boston, who conducted tests on totally and "legally" blind migraine patients.