The study, which was conducted in Norway, found that people with migraine with aura are more likely to have attacks during the summer light season than during the polar winter season.
"We found that this difference is due to the variation in light exposure--not due to changes in biological rhythms," said neurologist Karl Alstadhaug, MD, of Nordlandssykehuset Hospital in Bodo, Norway.
For the study, 169 women with migraine were interviewed and given questionnaires about their headaches. They included 98 people with migraine with aura and 71 with migraine and no aura. About two-thirds of the women had seasonal variations in the amount of headaches they experienced. Nearly half (47 percent) of those with migraine with aura had more frequent attacks during the light season, compared to 17 percent of those without aura.
"This supports the theory that, in people with migraine, the neurons in the occipital lobe of the brain, which is the part that is the primary site for vision, are hyperexcitable or easier to trigger," said Alstadhaug.
In the study, exposure to intense light could lead to attacks for 86 percent of women with migraine with aura, compared to 59 percent of those without aura. Sixty-two percent of the women with aura became extremely sensitive to light during and between attacks, compared to 41 percent of those without aura. Those with migraine with aura were also more likely to wear sunglasses to prevent attacks.
There were no differences between the two groups in sleep cycles, sleep disturbances, or shift work that would affect their sleep schedules.
The study was supported by the Somatic Research Fund at Nordlandssykehuset Hospital in Bodo, Norway.
The American Academy of Neurology, an association of more than 18,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer's disease, epilepsy, multiple sclerosis, Parkinson's disease, and stroke.
For more information about the American Academy of Neurology, visit www.aan.com.