Infrared light (850 nm) penetrates regular clothing 100 times more effectively than red light with a wavelength of 660 nm. Unlike ultraviolet and blue light, infrared light offers health benefits even when wearing everyday clothing.
The depth of light penetration depends on its wavelength, as well as its intensity and the amount of melanin in the skin. Red light in the range of 650–670 nm has proven effective in alleviating skin dermatitis after radiation exposure and in restoring retinal function in aging eyes. However, to expose deeper tissues, near-infrared light is more suitable, as it can penetrate up to 8 cm deep.
Furthermore, the greatest mitochondrial response to red and near-infrared light occurs in the morning, since the circadian rhythm of natural ATP production is at its peak, and in the morning, sunlight contains the highest relative proportion of near-infrared light.
Exposing human skin to “deep red” light with a wavelength of 670 nm for 15 minutes affected glucose tolerance.
Among other findings, the study showed that in people treated with red light shining on their backs, the rise in blood glucose levels after drinking a sugary beverage was reduced by 28%. Similarly, illuminating the backs of mice with infrared light helped improve their retinal function.
LED lights with added near-infrared (800–1000 nm) have been shown to have a calming and relaxing effect compared to standard LED lights.
In the study, heart rate variability was used as an indicator of relaxation, reflecting the activity of the sympathetic and parasympathetic branches of the autonomic nervous system. This system regulates automatic bodily functions — the sympathetic branch activates us in situations of threat or stress, while the parasympathetic branch promotes calm and recovery when we are safe. Volunteers exposed to light containing infrared wavelengths showed a significant increase in relaxation markers and an enhanced subjective sense of well-being.
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