Daily light exposure habits of youth with migraine: A prospective pilot study.

Background: Eighty percent of youth with migraine report photophobia. It is unknown if photophobia leads to light avoidant behavior, and if such behaviors worsen light sensitivity and disrupt sleep. Recently developed wearable, continuous light loggers allow us to address these open questions. We conducted a pilot study to determine the feasibility of measuring light exposure using wearable light loggers in youth with migraine. Methods: Youth 10 - 21 years old with a headache-specialist confirmed ICHD-3 diagnosis of migraine were recruited from CHOP headache clinics. Each participant recorded 7 consecutive days of light logging data from the ActLumus device worn as a pendant around the neck paired with a text-based daily migraine symptom diary during a typical school week between November and March 2024. Validated questionnaires were used to capture any headache and bad headache frequency, headache-related disability, visual sensitivity, fear-of-pain, and sleep disturbance and impairment. Percent time spent within recommended light exposure levels was calculated for the day, 3 hours prior to bedtime, and night. Power analysis was calculated to determine sample size needed for group comparison of baseline characteristics across light intensity and light timing metrics to aid in the design of larger studies. Results: Twenty youth with a median age 17 years [IQR 16, 19], 70% of whom were female completed 7 days of continuous light logger recording and daily headache diary. Data completion rates were high with 136/140 (97.1%) useable days of light logger data, and 100% compliance on the daily headache diary. Participant feedback on the study was positive; 85% would recommend the study to others. On average, participants received recommended light exposure during only 14.5% +/- SD 7.0 of daylight hours. By contrast, participants were more consistently below the recommended maximum light levels 3 hours prior to bed (77.5% +/- 21.6 of the time), and at night (99.1% +/- 2.9 of the time). Youth with chronic migraine (i.e., at least 15 headache days and 8 bad headache days per month) had daily light exposure patterns that were phase shifted 60 minutes later as compared to participants with non-chronic migraine. Power analyses suggest that future tests for differences in light exposure between migraine-characteristic groups (e.g., differing by headache frequency, severity, or disability) will require sample sizes on the order of 50 to 150 to reach 80% power with an alpha of 0.05. Conclusion: Measuring daily light exposure is feasible in pediatric populations with photophobia and reveals intriguing trends in youth with migraine that warrant further study.