Evaluation of green light exposure on headache frequency and quality of life in migraine patients: A preliminary one-way cross-over clinical trial

Abstract

Background: Pharmacological management of migraine can be ineffective for some patients. We previously demonstrated that exposure to green light resulted in antinociception and reversal of thermal and mechanical hypersensitivity in rodent pain models. Given the safety of green light emitting diodes, we evaluated green light as a potential therapy in patients with episodic or chronic migraine.

Material and methods: We recruited (29 total) patients, of whom seven had episodic migraine and 22 had chronic migraine. We used a one-way cross-over design consisting of exposure for 1-2 hours daily to white light emitting diodes for 10 weeks, followed by a 2-week washout period followed by exposure for 1-2 hours daily to green light emitting diodes for 10 weeks. Patients were allowed to continue current therapies and to initiate new treatments as directed by their physicians. Outcomes consisted of patient-reported surveys. The primary outcome measure was the number of headache days per month. Secondary outcome measures included patient-reported changes in the intensity and frequency of the headaches over a two-week period and other quality of life measures including ability to fall and stay asleep, and ability to perform work. Changes in pain medications were obtained to assess potential reduction.

Results: When seven episodic migraine and 22 chronic migraine patients were analyzed as separate cohorts, white light emitting diodes produced no significant change in headache days in either episodic migraine or chronic migraine patients. Combining data from the episodic migraine and chronic migraine groups showed that white light emitting diodes produced a small, but statistically significant reduction in headache days from (days ± SEM) 18.2 ± 1.8 to 16.5 ± 2.01 days. Green light emitting diodes resulted in a significant decrease in headache days from 7.9 ± 1.6 to 2.4 ± 1.1 and from 22.3 ± 1.2 to 9.4 ± 1.6 in episodic migraine and chronic migraine patients, respectively. While some improvement in secondary outcomes was observed with white light emitting diodes, more secondary outcomes with significantly greater magnitude including assessments of quality of life, Short-Form McGill Pain Questionnaire, Headache Impact Test-6, and Five-level version of the EuroQol five-dimensional survey without reported side effects were observed with green light emitting diodes. Conclusions regarding pain medications reduction with green light emitting diode exposure were not possible. No side effects of light therapy were reported. None of the patients in the study reported initiation of new therapies.

Discussion: Green light emitting diodes significantly reduced the number of headache days in people with episodic migraine or chronic migraine. Additionally, green light emitting diodes significantly improved multiple secondary outcome measures including quality of life and intensity and duration of the headache attacks. As no adverse events were reported, green light emitting diodes may provide a treatment option for those patients who prefer non-pharmacological therapies or may be considered in complementing other treatment strategies. Limitations of this study are the small number of patients evaluated. The positive data obtained support implementation of larger clinical trials to determine possible effects of green light emitting diode therapy.This study is registered with clinicaltrials.gov under NCT03677206.

Keywords: Green light; light therapy; migraine; non-pharmacological therapy.

Figure 1.

Study design. One-way cross-over clinical trial design. Patients were divided into episodic and chronic migraine groups based on the number of headache days per month. Patients with migraine were assigned to the control white light emitting diode (WLED) first then crossed over to the green light emitting diode (GLED) therapy. After 10 weeks of daily WLED, patients underwent a 2 week “washout” period and were then crossed over to the GLED.

Figure 2.

GLED exposure decreased headache days/month. (a) Number of headache days/month before and after patients were exposed to WLED. Results are presented for all patients and divided in two cohorts: Episodic and chronic migraine patients (n[WLED]epi = 8, n[WLED]chro = 17). WLED did not decrease the number of headache days/month in both episodic and chronic migraine patients, but a small significant reduction was observed when both cohorts were pooled. (b) GLED exposure produced a statistically significant reduction in the number of headache days/ month in both episodic and chronic migraine groups (n[GLED]epi = 7, n[GLED]chro = 19). Scatter plots, with every point representing a study subject: The bars represent the average and the error bars represent the standard error of the mean (Wilcoxon matched-pairs signed rank test, *p<0.05, ***p<0.001).

Figure 3.

GLED exposure decreased the numeric pain scale (NPS). (a) WLED did produce a slight reduction in the NPS for the chronic migraine group (n[WLED]epi = 8, n[WLED]chro = 21). (b) GLED exposure produced a greater and statistically significant reduction in the NPS in both episodic and chronic migraine groups (n[GLED]epi = 7, n[GLED]chro = 22). Data presented as Average ± SEM, standard error of the mean (Wilcoxon matched-pairs signed rank test, *p<0.05, ***p<0.001).

Figure 4.

GLED exposure improved the Headache Impact Test-6 (HIT-6) results. (a) WLED exposure did not produce a significant reduction in HIT-6 scores (scale 36–78, where 36 = No impact from migraine, 78 = worst possible impact from migraine) (n[WLED]epi = 6, n[WLED]chro = 18). (b) GLED exposure produced a statistically significant reduction in the HIT-6 scores in all migraine groups (n[GLED]epi = 6, n[GLED]chro = 21). Data presented as average ± SEM, standard error of the mean (Wilcoxon matched pairs signed rank test, *p<0.05, ***p<0.001).

Figure 5.

GLED exposure improved all quality of life parameters reported using the modified University of Arizona pain clinic follow up questionnaire. WLED exposure had minimal improvement of several parameters in episodic (a), chronic (b), and all migraine patients (c). The following criteria were evaluated: Perceived percent improvement of migraine pain intensity, migraine headache frequency, pain duration, ability to fall asleep, ability to stay asleep, work, exercise and doing chores, after completion of WLED therapy compared with baseline (n[WLED]epi = 6–8, n[WLED]chro = 19–21). On the contrary, GLED exposure demonstrated significantly greater improvements in all measured parameters in episodic, chronic and combined migraine groups. (n[GLED]epi = 6–7, n[GLED]chro = 15–22). Data presented as average ± SEM, standard error of the mean (Mann-Whitney test, *p<0.05, **p<0.01, ***p<0.001).

Figure 6.

Five-level version of the EuroQol five-dimensional survey (EQ-5D-EL) evaluation after WLED or GLED exposure. EQ-5D-5L index and patients’ own perception of health before and after WLED or GLED, in episodic (a), chronic (b) and combined (c) groups of patients. Index scale 0–1 where 0.worst quality of life, 1.best quality of life. Health perception scale 0–100, where 0 = worst imagined health, 100 = best imagined health. WLED had a statistically significant improvement of the EQ-5D-5L index in both combined and chronic migraine groups. WLED exposure did not produce any improvement of the patients’ own perceived health using the EQ-5D-5L survey (n[WLED]epi = 7, n[WLED]chro = 21). GLED exposure had a statistically more significant improvement of the EQ-5D-5L index in episodic, chronic, and combined migraine groups. GLED exposure also produced a statistically significant improvement of the patients’ own perceived health in both all groups (n[GLED]epi = 7, n[GLED]chro = 18). Data presented as average ± SEM, standard error of the mean (Wilcoxon matched-pairs signed rank test, *p<0.05, ***p<0.001).