NEW YORK (Reuters Health) - Weather has long been considered one of many potential migraine triggers, but a new study links lightning, specifically, to the onset of the severe headaches that plague more than 28 million Americans.
Based on headache logs and weather data for Ohio and Missouri, researchers found that people were 28 percent more likely to experience a migraine on days when lightning struck within 25 miles of their home.
"We're very surprised and very happy with the results in that this is the first study to link lightning to migraines," said Dr. Vincent Martin, the study's senior author from the University of Cincinnati College of Medicine in Ohio.
Migraines are severe headaches - sometimes accompanied by light sensitivity, visual hallucinations or nausea - that can disable a person for hours or even days at a time. The majority of migraine sufferers are women.
Martin told Reuters Health that a migraine may result from a person experiencing certain "triggers," such as stress, lack of sleep and dehydration.
Previous research has also found links between the onset of migraines and high barometric pressure, high temperatures and high humidity.
Most of the past studies looking at weather and migraines, however, relied on an individual's observations and did not always account for other, possibly unseen, local weather conditions, the researchers write in the journal Cephalalgia.
For the new study, they used information collected from three sensors that track lightning near Cincinnati, Ohio, and five sensors near St. Louis, Missouri. Those sensors allowed the researchers to know where and when lightning struck and the intensity of each strike.
They also used the headache diaries from two previous studies of 90 migraine sufferers in those areas who were between 18 and 65 years old. In those diaries, the participants recorded their headaches for three to six months.
After comparing the weather data with the headache journals, the researchers found that a lightning strike within 25 miles of a person's house was linked to a 31 percent increased risk of any kind of headache, and a 28 percent increased risk of the more severe migraine headache.
Martin said that could mean an extra one to three migraines per month for an individual, but he added that it depends on the person and the weather.
As for how lightning might affect migraine occurrences, Martin said it could be that the electromagnetic waves and ozone created by the lightning have something to do with it.
"The other theory is that when these thunderstorms roll in they can create more allergy spores in the environment," he said, which could create a problem for some people.
But the researchers cannot say for certain that lightning causes migraines, even though they used a computer model to account for other meteorological changes that occur during a thunderstorm.
In an accompanying editorial, Dr. Hayrunnisa Bolay of Gazi University in Ankara, Turkey, cautioned that the study had limitations, including its failure to account for the participants' own individual risk factors.
"In brief, one can only conclude that weather conditions associated with lightning have the potential to induce headache in migraine patients," she wrote.