Smithsonian.com

A new study suggests that lightning alone—even without the other elements of a thunderstorm—might trigger migraines. Image via Wikimedia Commons

Migraine sufferers know that a variety of influences—everything from stress to hunger to a shift in the weather—can trigger a dreaded headache. A new study published yesterday in the journal Cephalalgia, though, suggests that another migraine trigger could be an unexpected atmospheric condition—a bolt of lightning.

As part of the study, Geoffrey Martin of the University of Cincinnati and colleagues from elsewhere asked 90 chronic migraine sufferers in Ohio and Missouri to keep detailed daily diaries documenting when they experienced headaches for three to six months. Afterward, they looked back over this period and analyzed how well the occurrence of headaches correlated with lightning strikes within 25 miles of the participants’ houses, along with other weather factors such as temperature and barometric pressure.

Their analysis found that there was a 28 precent increased chance of a migraine and a 31 precent chance of a non-migraine (i.e. less severe) headache on days when lightning struck nearby. Since lightning usually occurs during thunderstorms, which bring a host of other weather events—notable changes in barometric pressure—they used mathematical models to parse the related factors and found that even in the absence of other thunderstorm-related elements, lightning alone caused a 19 percent increased chance of headaches.

Despite these results, it’s probably a bit premature to argue that lightning is a definitive trigger of migraines. For one, a number of previous studies have explored the links between weather and migraine headaches, and the results have been unclear. Some have suggested that high pressure increases the risk of headaches, while others have indicated that low pressure increases the risk as well. Other previous studies, in fact, have failed to find a link between migraines and lightening, in particular.

This study’s results are still intriguing, though, for a few reasons. One key element of the study was that, instead of using instances of lightning as reported by individuals on the ground, the researchers relied upon a series of ground sensors that automatically detect lightning strikes in the areas studied with a 90 percent accuracy. The researchers say this level of precision improves upon previous research and makes their results more indicative of the actual weather outside.

The study also looked at the polarity of lightning strikes—the particular electrical charge, whether positive or negative, that a bolt of lightning carries as it surges from the clouds to the ground—and found that negatively charged lightning strikes had a particularly strong association with migraines.

The researchers don’t have a clear explanation yet for how lightning might play a role, but they mention a wide variety of possibilities. ”There are a number of ways in which lightning might trigger headaches,” Martin said. “Electromagnetic waves emitted from lightning could trigger headaches. In addition, lightning produces increases in air pollutants like ozone and can cause release of fungal spores that might lead to migraine.”