Migraine sufferers know that a debilitating attack can strike unpredictably.
Now a new model developed by scientists could help predict when a painful headache might next occur.
The test involves monitoring stress levels experienced the day before, and could allow doctors to treat patients with preventative therapies.
Patients reported experiencing the greatest amount of stress around 24 hours previously.
Lead author Dr Tim Houle, associate professor of anaesthesia and pain medicine at Massachusetts General Hospital and Harvard Medical School, said: ‘We know that certain people are at greater risk of having an attack over other people, but within a person, we have not been able to predict increased risk for an attack with any level of accuracy.
‘This study demonstrates that it is quite possible to forecast the occurrence of a headache attack within an individual headache sufferer.’
The researchers, writing in the journal Headache, note that because migraines are unpredictable, patients are often unprepared to take medications in a timely manner or they choose to wait to take medications until their pain escalates.
Migraine affects one billion people worldwide, according to Migraine Research Foundation.
A migraine is more than just a headache – as well as pain other symptoms can include disturbed vision, sensitivity to light, sound and smells, feeling sick and vomiting.
The incapacitating nature of migraines is underestimated and migraine is the sixth most disabling illness in the world, it says.
While most sufferers experience attacks once or twice a month, more than four million people have chronic daily migraine, with at least 15 migraine days per month.
More than 90 percent of sufferers are unable to work or function normally during their migraine.
The study looked at 95 individuals over 4,195 days of diary data and discovered that patients experienced a headache attack on nearly 39 percent days.
The team said that a simple forecasting model using either the frequency of stressful events or the perceived intensity of these events had ‘promising predictive value.’
While the participants reported low to moderate levels of stress overall, stress was the greatest on days preceding a headache.
Dr Houle said that further studies work need to be carried out to make the prediction model more accurate before they will be of widespread use clinically.