FRIDAY, April 15, 2005 (HealthDay News) -- Intense summer light in arctic regions may encourage more headaches in people with migraines, according to a Norwegian study.
This effect is only true for people with migraine accompanied by an aura, a warning sensation that occurs before a migraine begins. These people are more likely to have attacks during the light-filled summer season than in the dark polar winter, the study found.
Researchers interviewed 169 women with migraine, who also filled out questionnaires. Of the women, 98 had migraine with aura and 71 had had migraine with no aura. About two-thirds of the women said they experienced seasonal variations in their rate of migraine.
The study found 47 percent of those with migraine with aura had more frequent attacks during summer, compared to 17 percent of those with migraine without aura.
"We found that this difference is due to the variation in light exposure, not due to changes in biological rhythms," neurologist Dr. Karl Alstadhaug said in a prepared statement. He said the findings support the theory that, in people with migraine, cells in the occipital lobe of the brain -- responsible for vision -- may become hyperexcitable in the presence of intense light, helping to trigger migraine.
The study found very bright light could trigger attacks in 86 percent of women with migraine with aura, compared to 59 percent of women with migraine without aura. In addition, 62 percent of the women with aura became extremely sensitive to light during and between migraines, compared to 41 percent of the women without aura.
Women with aura were also more likely to wear sunglasses to prevent migraine, the study found.
The study was presented April 14 at the American Academy of Neurology annual meeting, in Miami Beach, Fla.
The National Headache Foundation has more about migraine.