PNNL

Abstract

Sunlight contains approximately equal amounts of visible light and near-infrared (NIR) radiation. Once believed to be biologically inconsequential, NIR has been removed from most modern electric light sources, including light-emitting diodes (LEDs), as an energy-saving measure. However, NIR is now recognized as biologically active, and is used in therapeutic photobiomodulation treatments for a wide range of physical, cognitive, and emotional disorders. It remains unknown whether NIR in daily indoor illumination influences human mental and physical health, and whether the absence of NIR in LEDs could consequently be cause for concern. The proposed within-subjects counterbalanced human factors experiment will investigate the acute effects of NIR in indoor lighting on aspects of cognition, emotion, and cardiovascular physiology in a controlled laboratory setting. It is expected that cognitive performance, mood, environmental satisfaction, and autonomic function will be improved under lighting containing the normal fractional amount of NIR in typical daylight, compared to under lighting containing nearly zero NIR, as in conventional LED lighting. To the best of our knowledge, this is the first study to examine whether individuals are influenced at a cognitive, emotional, or physiological level during exposure to NIR in the ambient illumination.