258 Blue Blockers’ Ability to Block Circadian-Active Light Emitted from a Tablet

Abstract

\n \n \n Short-wavelength light emitted from electronic devices in the evening can harm circadian health by suppressing endogenous melatonin and phase-delaying the timing of the wake-sleep cycle. Blue-blocking glasses are one possible intervention to reduce this exposure. The present study evaluated the differential ability of commercially available blue-blockers to filter out the blue range of visible-spectrum light emitted by a common electronic device.\n \n \n \n A calibrated spectroradiometer (Ocean Insight), cosine corrector, optic fiber, and software package were used to measure the absolute irradiance (uW/cm^2/nm) emitted from a commercially-available computer tablet (iPad) displaying a blank white screen in a closeted dark room. Thirty-one commercially-available blue-blockers were individually placed between the cosine corrector and the tablet. At a standardized distance and angle, the resulting intensity profile was measured and analyzed. Each lens was evaluated individually relative to the light source and then evaluated across subtypes, including red-tinted lenses (RTL), orange-tinted lenses (OTL), orange-tinted lenses with blue reflectivity (OBL), brown-tinted lenses (BTL), yellow-tinted lenses (YTL), and clear reflective blue lenses (RBL).\n \n \n \n There was significant variation in tablet-generated light-blocking across the full spectrum (one-way ANOVA, p < 0.0001) and for the 440-530nm range in particular (one-way ANOVA, p < 0.0001). RTL blocked 99%, OTL blocked 81%, OBL blocked 75%, BTL blocked 83%, YTL blocked 33%, and RBL blocked 17% of broadspectrum light (380-780nm). In the 440nm-530nm range, RTL, OTL, and OBL blocked 100% of the emission, while BTL blocked 81%, YTL blocked 47%, and RBL blocked 18% of it.\n \n \n \n When using a popular tablet device, RTL, OTL and OBL blocked the most circadian photosensitive parts of the light exposure, indicating they can best preserve the timing of endogenous melatonin secretion in the presence of tablet light at night. By contrast, RBL demonstrated very little efficacy.\n \n \n \n R01MD011600, R01DA051321\n