Evaluation of wearable light dosimeters for circadian lighting: spectral, spatial, photometric, melanopic, and...

Light is the primary stimuli for the entrainment of human circadian rhythms and holds enormous potential in aiding precision medicine. Laboratory studies highlight the roles of photic history, intensity, spectrum, and timing, but field translation gets complicated by real-world confounds. Measuring daily light exposure in realistic conditions requires an accurate, durable, and affordable wearable light dosimeter. Here, the spectral, spatial, and thermal performance of three wearable dosimeters (LYS Buttons, Blue Iris Specks, and Actiwatch Spectrum Plus) are investigated and benchmarked against a calibrated spectroradiometer under multipole lighting conditions. Light measurements taken by dosimeters under various lighting conditions are then used to calculate melanopic and photometric measures. The LYS Button was the easiest to use, albeit with reduced accuracy. The Blue Iris Speck had the highest photometric and data-logging accuracy. The Actiwatch had the poorest photometric performance, which raises caution for scientific use. The results inform device development and protocol design for chronobiology and sleep research. Future studies should evaluate and compare the performance of the dosimeters based on body-worn position.