Known migraine triggers may not be the cause of the splitting headaches says a study.
Researchers in Denmark found that excessive light and exercise did not seem to cause attacks in migraine sufferers.
Many people add to the discomfort of migraines by worrying about their triggers.
The study looked at 27 people who suffered from migraines with aura - preceding symptoms that mark the onset of the headache, said ABC News.
Using experiments involving excessive light and exercise - two phenomena believed to cause the attack - the researchers tested whether they did in fact trigger a migraine.
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It turns out they did not.
Only three participants had an attack after the study was completed.
“There are a lot of things about headache and migraine that are accepted as true but that remain untested,” said neurologist Peter Goadsby, reported WebMD.
“The results of this study may surprise some patients.”
The study was published in the journal Neurology.