Infrared exposure improves human colour vision undermined by LED light.

Life evolved under sunlight (200-4000nm). Incandescent lighting was similar (200-3000nm). But modern light-emitting diodes (LED) produce only a narrow band of visible light (400-700nm), eliminating >90% of the solar spectrum. Light impacts life, partly through mitochondrial modulation with different wavelengths triggering opposing metabolic responses. Longer red/infrared wavelengths (650-1000nm) improve metabolism and ageing patterns, while blue light (420-450nm) undermines these processes. The retina has the highest metabolic rate in the body and the greatest density of mitochondria. Hence, visual ability may be vulnerable to changes in the light environment which negatively affects mitochondrial performance. We ask if standard LED lighting reduces visual performance in terms of colour discrimination ability, and whether adding 850nm infrared improves it. We tested colour discrimination with a standard Farnsworth-Munsell 100-Hue test in 55 subjects then divided them into those exposed to standard LED desk lighting or LED lights supplemented with 850nm infrared for a week. Controls were unexposed. There were no changes in controls but significant reductions of 33% in colour performance scores in the LED group and significant improvements of 23% in colour performance scores in those supplemented with 850nm. The implications for public health warrant further investigation as LED lighting continues to be widely adopted in the built environment.