Some Rays of Sunshine Pass Through the Human Body

Red and Near-Infrared irradiate every cell boosting mitochondrial energy production

We have talked previously about the breakthrough studies on infrared light and human health by the teams led by Professors Glen Jeffrey and Robert Fosbury at University College, London. Now just published is an especially “illuminating” paper reporting that longer wavelengths in sunlight pass through the human body and have a systematic effect which improves glucose metabolism and vision.¹

Most of the red and near-infrared rays from sunlight are absorbed by the cells of the body so that amount of light that passes completely through is a small fraction. But along the way every cell is bathed by at least some near-infrared rays from sunlight. And wearing normal light summer clothing does not block these rays.

From Jeffrey et al. (2025) showing the spectrum of daylight (blue curve) shining on one side of the chest, and the spectrum (red curve) measured on the opposite side that has passed completely through the chest. Only wavelengths between about 600 - 900 nm (red and near-infrared) pass through the body.

Health Impact of Infrared Light

We are only starting to realize the full implications of this finding. One effect that is well documented is that red & near-infrared light increases mitochondrial membrane potential and ATP production, especially when they have declined with age or disease. ATP (adenosine triphosphate) production in the mitochondria is a key source of energy for biological metabolism, and when boosted with near-infrared light results in improved function and health.

Only a few assays which reflect this effect in humans have been studied so far. One is color vision in the retina of the eye where the concentration of mitochondria is the highest in the body. Both blue and red color vision are significantly boosted after near-infrared light treatment.

Another assay is the effect of near-infrared light on glucose metabolism. The classic diabetes test measures blood glucose levels before and after consuming a sugar drink. How high the blood glucose rises and how soon it falls back to normal levels are diagnostic of diabetes. Near-infrared light has an anti-diabetic effect by lowering blood glucose during this glucose tolerance test.

Living Indoors Under LED Light Impacts Our Health

Our modern lifestyles deprive us of near-infrared light. Window glass blocks much of the near-infrared from daylight, and conventional blue-rich LED lights do not emit any near-infrared light - unlike the now banned incandescent and halogen light bulbs.

Worse still the 450 nm blue spike in modern LEDs suppresses mitochondrial energy production, and undermines our energy and health

In seeking so-called “energy efficiency”, government regulators have used a false metric of “lumens per watt” which only measures the electrical efficiency of producing visual brightness. Blue-rich LEDs are heavily favored by this arbitrary metric, but other health promoting aspects of the full natural daylight spectrum are ignored, and as a result we are deprived of healthy lighting.

To learn more about what needs to be done to ensure we have healthy light learn about our Campaign for Healthy Lighting at circadianlight.org. On March 31, 2025, over 200 Americans submitted a formal petition for rulemaking to the US Department of Energy (DOE) to create a protected class of "General Wellness Light Bulbs" (including circadian-friendly, infrared, & full spectrum) that is exempt from the 125 lumens per watt rule.

The full text of the Petition can be found at https://circadianlight.org/doe-petition/

Please sign up to receive updates so that you can respond when this proposal becomes open for public comments.

Getting Outside Every Day is a Key to Good Health

One encouraging finding from the Jeffrey-Fosbury studies is that it does not rake much red and near-infrared light exposure to have a lasting effect. 15 minutes of near infrared light exposure can have a beneficial effect that lasts 24 hours or more.

So, getting outside regularly in full daylight, especially in the mornings, is key to good health. Use whatever excuse it takes to get you out of the door - walking the dog, jogging, biking, playing golf, mowing the lawn, or simply reading a book on the patio - anything works as long as you get a healthy dose of natural daylight.

Further Resources

For more insights into what we have done to ourselves by moving indoors and switching on narrow spectrum blue-rich LED lights, and what you should do about it, see my book THE LIGHT DOCTOR.

Remember the light we see is as important our health as the food we eat, the water we drink, and the air we breathe.

1. Jeffrey G., Fosbury R. et al (2025) Longer wavelengths in sunlight pass through the human body and have a systematic effect which improves vision. Scientific Reports 15: 24435 https://www.nature.com/articles/s41598-025-09785-3