Importance of the Unseen: Near-Infrared Light Regulates Human Glucose Levels in the Built Environment

Life evolved under sunlight spanning wavelengths from 300 to 2500 nanometers, but modern indoor lighting using standard Light Emitting Diodes (LEDs) is limited to a range of 400 to 650 nanometers. Different wavelengths of light can impact human metabolism by affecting the function of mitochondria. Light in the 670-900 nanometer range supports mitochondrial health, while light in the Soret band, which spans 420 to 450 nanometers, can impair mitochondrial function.

When individuals are exposed to LED lighting, their metabolic capacity is diminished, leading to a reduced need for blood sugar to produce adenosine triphosphate (ATP). Conversely, longer wavelengths that boost mitochondrial function raise the demand for blood sugar, resulting in lower serum glucose levels.

In this study, researchers manipulated lighting conditions in windowless offices. Subjects were exposed to either standard LED desk lamps or lamps that included an additional 850 nanometer wavelength for two hours every morning over the course of three days. Blood sugar levels were measured using two distinct methods: an oral glucose tolerance test and continuous glucose monitoring.

The findings showed that individuals exposed to standard LEDs experienced significantly higher blood glucose levels, while those exposed to lamps with added 850 nanometers had significantly lower blood glucose levels. These real-world results underscore the critical role that light plays in regulating metabolism and raise concerns about public health in interior environments where people now spend the vast majority of their lives.