Weather has long been considered one of many potential migraine triggers, but a US study now links lightning, specifically, to the onset of the severe headaches that plague millions.
Researchers whose work appeared in the journal Cephalalgia found that, based on headache logs and weather data for the two US states of Ohio and Missouri, people were 28 percent more likely to experience a migraine on days when lightning struck within 40 kilometers (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 senior author Vincent Martin, 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 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.
But most of the past studies on weather and migraines relied on an individual's observations and did not always account for other, possibly unseen, local weather conditions, the researchers wrote.