By Pat Anson, PNN Editor

New research is shining a light on an unusual treatment for migraine headaches: green light therapy.

In a small study involving 29 migraine patients, University of Arizona Health Sciences researchers found that exposure to green light for one to two hours daily reduced headache pain by 60% and significantly reduced the frequency of migraines.

"This is the first clinical study to evaluate green light exposure as a potential preventive therapy for patients with migraine, " said lead author Mohab Ibrahim, MD, an associate professor in the Departments of Anesthesiology and Pharmacology at UArizona College of Medicine-Tucson. "As a physician, this is really exciting. Now I have another tool in my toolbox to treat one of the most difficult neurological conditions: migraine."

Of the 29 patients who participated in the study, seven had episodic migraine and 22 had chronic migraine. All were exposed to white light for one to two hours a day for 10 weeks. After a two-week break, they were exposed to green light for 10 weeks.

Participants also completed regular surveys and questionnaires to track the number and intensity of their headaches, as well as quality of life issues such as the ability to fall and stay asleep or to work.

Using a pain scale of 0 to 10, participants self-reported that green light exposure resulted in a 60% average reduction in their headache pain, from 8 to 3.2.

Green light also shortened the duration of headaches, and improved participants' ability to fall and stay asleep, perform chores, exercise, and work. None of the patients reported any side effects.

"In this trial, we treated green light as a drug," Ibrahim said. "It's not any green light. It has to be the right intensity, the right frequency, the right exposure time and the right exposure methods. Just like with medications, there is a sweet spot with light."

Participants were given green light emitting diodes – LED lights – with instructions to follow while completing the study at home. They were also allowed to continue current migraine therapies and to initiate new treatments if directed by their physicians.

"One of the ways we measured participant satisfaction was, when we enrolled people, we told them they would have to return the light at the end of the study. But when it came to the end of the study, we offered them the option to keep the light, and 28 out of the 29 decided to keep the light," said Ibrahim.

Most of the study participants - 86% of episodic migraine patients and 63% of chronic migraine patients - reported the number of headache days per month was reduced by at least 50 percent. Episodic migraine is characterized by up to 14 headache days per month, while chronic migraine is 15 or more headache days per month.

Ibrahim and co-author Amol Patwardhan, MD, have been studying the effects of green light therapy for several years.

"Despite recent advances, the treatment of migraine headaches is still a challenge," said Patwardhan, an associate professor and the vice chair of research in the Department of Anesthesiology. "The use of a nonpharmacological therapy such as green light can be of tremendous help to a variety of patients that either do not want to be on medications or do not respond to them. The beauty of this approach is the lack of associated side effects."

Dr. Ibrahim has been contacted by doctors in Europe, Africa and Asia, asking for information about green light therapy for their own patients.

"As you can imagine, LED light is cheap," Ibrahim said. "Especially in places where resources are not that available and people have to think twice before they spend their money, when you offer something affordable, it's a good option to try."

The study findings were published online in Cephalalgia, the journal of the International Headache Society.

A 2016 study by researchers at Beth Israel Deaconess Medical Center in Boston also found that green light therapy reduced headache severity in migraine sufferers. Patients in that study were exposed to different intensities of blue, green, amber and red light. Most patients said their migraines got worse when exposed to white, blue or amber light, while green light was found to reduce pain in 20 percent of patients.

About a billion people worldwide suffer from headaches caused by migraines, which affect three times as many women as men. Migraine affects more than 37 million people in the United States, according to the American Migraine Foundation. In addition to headache pain and nausea, migraine can cause vomiting, blurriness or visual disturbances, and sensitivity to light and sound. About half of people living with migraine are undiagnosed.