"In spring and fall it's common for patients to have seizures while driving on the road because the sunlight flickers through the trees," said Paolicchi. Evenly-spaced reflective pylons can also trigger seizures, she said.
The odds of having photosensitive epilepsy is up to 40 percent higher in people who have siblings with the disorder -- a sign of its strong genetic roots.
"There's a large group of people working together to try to understand the genetic basis of epilepsy," said Lowenstein, who is part of the Epilepsy Phenone/Genome Project -- a study sponsored by the National Institute of Neurological Disorders and Stroke. Roughly 4,000 patients have joined the study, which aims to improve care through better understanding of the disorder. The researchers ultimately hope to get to 5,000 patients.