Green Light Exposure Therapy May Reduce Migraine Frequency

In individuals suffering from chronic (CM) and episodic migraine (EM), results from a preliminary study show exposure to green light therapy significantly reduced the number of headache days and improved both intensity and duration of headache attacks.

Although several acute and preventive therapies and nonpharmacological approaches exist for the condition, many patients experience concurrent adverse effects (AEs) while others do not achieve adequate pain control.

In addition, medication overuse headache can occur in migraineurs who frequently use medications like triptans, ergots, barbiturates, or opiates. High-frequency use of these medications may not only increase the frequency and intensity of headaches but can also lead to AEs such as gastrointestinal issues, renal toxicities, medication dependency, and withdrawal.

Based on these findings, offering a nonpharmacological therapeutic option could be useful to migraineurs as a standalone or as a complement to pharmacotherapies, the authors wrote.

Researchers at The University of Arizona recruited individuals with CM (n = 22) and EM (n = 7) between August of 2016 and October of 2019 to take part in a one-way cross-over study. Patients who experienced up to 14 headache days per month were classified as having EM while CM was defined as 15 or more headache days per month.

All participants were over the age of 18, exhibited an average headache pain intensity of 5 of 10 or greater based on the numeric pain scale (NPS) over the 10 weeks prior to the study, and were not satisfied with the preventive or acute migraine treatment(s) they currently received.

Patients were exposed to white light-emitting diodes (WLED) for 10 weeks for 1 to 2 hours daily, then completed a 2-week washout period. This period was followed by exposure for 1 to 2 hours daily to green light-emitting diodes (GLED) for 10 weeks. Patients did not know which light therapy was the intervention and which acted as a control. Participants were also free to continue or discontinue any migraine treatments recommended by their physicians during the study.

During exposure “patients were encouraged to participate in activities that did not require external light sources such as listening to music, reading books, exercise, or any similar activities,” the researchers said. “We asked the patients to undergo the light therapy at the same time everyday all at once.” Participants completed 7 surveys at baseline and every 2 weeks thereafter while time logs, information on daily medication intake, and migraine diary surveys were recorded daily.

At the time of enrollment, the mean (standard error of mean [SEM]) patient age was 52.2 (3) years, and the majority (n = 27) were female. At baseline, patients exhibited a mean pain during migraine attacks of 8.52 (0.25) of 10, reported via the NPS.

Analyses revealed:

• GLED significantly reduced the number of mean headache days/month in the EM and CM groups from 7.9 (1.6) to 2.4 (1.1) and 22.3 (1.3) to 9.4 (1.6) days, respectively
• Combined EM and CM data showed a significant reduction in mean headache days/month for GLED from 18.4 (1.6) to 7.4 (1.3) days, a reduction of ~60%
• There was an 86% responder rate (6 of 7 patients) for EM patients and 63% responder rate (12 of 19) for CM patients
• Changes in the number of headache days/month of the EM and CM groups before and after WLED were not significant
• In chronic migraineurs, GLED shortened the duration of headaches and improved participants' ability to fall and stay asleep, perform chores, exercise, and work
• There were no reported AEs of either light therapy

Throughout the study period, no participants reported beginning new medications or procedures recommended by physicians. In addition, no participants had ocular diseases or colorblindness or used tinted contact lenses.

Rates of reduction of headache days per month induced by GLED were comparable to those resulting from pharmacological therapies like propranolol (2.4 days/month), topiramate (3.6), and calcitonin gene-related peptide/receptor antibodies (4.6-8).

Participant satisfaction with the study was also high. "When we enrolled people, we told them they would have to return the light at the end of the study,” explained Mohab Ibrahim, MD, PhD, a lead author 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."

A small sample size and the use of light therapy only in calm environments mark limitations to the study. The researchers plan to recruit a greater number of patients in future studies. “The safety and efficacy observed coupled with the simplicity of this method merit further investigations to fully investigate the role of GLED for migraine prevention,” they concluded.

Reference

Martin LF, Patwardhan AM, Jain SV, et al. Evaluation of green light exposure on headache frequency and quality of life in migraine patients: a preliminary one-way cross-over clinical trial. Cephalalgia. Published online September 9, 2020. doi:10.1177/0333102420956711