Spectral Composition of Ambient White Light Modulates Photophobia and Headache Intensity During Migraine Attacks

Photophobia is a common and disabling symptom among those with migraine. Studies show that short-wavelength and long-wavelength light can worsen migraine pain, while narrow-band green light may provide relief. However, monochromatic lighting is not visually pleasant and practical for daily environments. This study examined whether spectral modifications of white light influence visual discomfort and migraine headache intensity during migraine attacks.

In a randomized crossover design, 21 adults with migraine were studied during an untreated migraine attack. Participants were exposed to four spectral white light conditions (blue-, cyan-, green-, and red-enriched) at 400 lx for 10 minutes each, in randomized order, with 5 minutes of dark adaptation between conditions. Headache intensity was assessed pre- and post-exposure, visual discomfort was rated once per minute, and pupil size was measured at the end of each exposure. Data were analyzed using repeated-measures analysis of variance (ANOVA) with Bonferroni-adjusted pairwise comparisons.

There was a significant main effect of lighting condition on visual discomfort, with blue-enriched white light causing significantly greater discomfort (mean 7.58 on a 0-10 numeric rating scale, SE 0.26) compared to all other lighting conditions (p < 0.001), and green-enriched light causing the least discomfort (mean 4.78, SE 0.25), significantly less than blue- and cyan-enriched light (p < 0.001). Headache intensity increased with blue-enriched white light (mean + 1.67 on a 0-10 numeric rating scale p < 0.001) and cyan-enriched light (+ 0.95; p < 0.001). In contrast, green-enriched and red-enriched light did not increase headache intensity (green, - 0.38; p = 0.134; red, + 0.24; p = 0.521). Pupil size varied by spectrum (F(3,60) = 8.09, p < 0.001, η² = 0.288), with greater constriction under blue and cyan light and less under green, consistent with subjective discomfort.

The spectral composition of white light influences light sensitivity and headache intensity during migraine attacks. Findings suggest that green-enriched white light may offer a practical, non-pharmacological strategy for managing migraine symptoms in everyday environments.