Light sensitivity is a frequent symptom of migraine, but according to a study done earlier this year, a certain kind of light may reduce migraines.

A study done by researchers at Beth Israel Deaconess Medical Center (BIDMC) in Boston has found that exposing migraine sufferers to a narrow band of green light can reduce light sensitivity, known as photophobia, and headache severity. The study was published in the May 2016 edition of Brain.

“Although photophobia is not usually as incapacitating as headache pain itself, the inability to endure light can be disabling,” said lead author Rami Burstein, PhD, Vice Chair of Research in the Department of Anesthesia, Critical Care and Pain Medicine and Academic Director of the Comprehensive headache Center at BIDMC.

Close to 90% of migraineurs suffer from photophobia during an attack and can force them to retreat to a dark room. Burstein said this isolates sufferers from work, family, and everyday activities.

In this study, researchers exposed patients suffering from an acute migraine attack to different intensities of blue, green, amber, and red light. At high intensities (comparable to a well-lit office), nearly 80 percent of patient reported intensification of headache with exposure to all lights but green.

This study followed a discovery by BIDMC five years ago that showed blue light negatively impacts migraine patients who are blind. The study compared two groups: those who are completely blind and unable to sense light; and those who were legally blind but able to sense light.

In a 2010 press release, Burstein said: “This suggested to us that the mechanisms of photophobia must involve the optic nerve, because in totally blind individuals, the optic nerve does not carry light signals to the brain.”

After the green light study, researchers applied a technique to test animal models of migraine to study neurons in the thalamus, an area of the brain that transmits light from the eye to the cortex. Neurons were found to be least responsive to green light, explaining why the migraine brain responds favorably to green light, according to the press release.

“These findings offer real hope to patients with migraines and a promising path forward for researchers and clinicians,” Burstein said.

Burstein is now working to develop more affordable options for migraine patients with light sensitivity. He is developing light bulbs that emit green light at low intensity, as well as sunglasses that block all but the narrow band of green light.