Breakthrough Study: Sunlight Passing Through the Body Improves Vision by Boosting Mitochondria

A groundbreaking 2025 study reveals that near-infrared sunlight can pass through your chest and improve your eyesight — even without a single photon reaching your eyes.

For decades, we’ve been told to shield our eyes from the sun. But what if sunlight — specifically its longer, invisible wavelengths — could actually improve your vision? A landmark study published in Scientific Reports on July 8, 2025, suggests exactly that.

Researchers led by Professor Glen Jeffery at University College London made a stunning discovery: near-infrared light (830–860 nm) can penetrate the human body and trigger a systemic effect that significantly improves visual function 24 hours later. Even more remarkably, this improvement occurred in subjects whose eyes were completely shielded from light.

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The Science: How Light Feeds Your Mitochondria

At the heart of this discovery lies the mitochondrion — the power plant of every cell in your body. Mitochondria produce ATP, the energy currency that fuels all biological processes. As we age or face disease, mitochondrial function declines, ATP production drops, and inflammation rises.

But mitochondria are light-sensitive. Longer wavelengths in the 660–1000 nm range (red and near-infrared) have been shown to increase mitochondrial membrane potential and boost ATP production. This effect is partly attributed to the absorption of light by cytochrome c oxidase — a key enzyme in the mitochondrial energy pathway.

Shorter wavelengths (400–450 nm — the blue light common in LEDs and screens) have the opposite effect, reducing mitochondrial function. This helps explain why modern LED lighting, which is spectrally narrow, may be undermining our visual and metabolic health.

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What the Study Found

The researchers measured infrared wavelengths from sunlight after they passed through the human thorax (chest). They then delivered 830–860 nm light to the chests of subjects in 15-minute controlled exposures.

Key Results:

• Clothing was not a barrier — it reduced intensity but did not block the beneficial wavelengths.
• Significant visual improvement was measured 24 hours later.
• Improvement occurred even when light was blocked from the eyes.

This demonstrates a systemic (“abscopal”) effect — light exposure to one part of the body (the chest) improved function in a distant organ (the eyes).

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Why This Matters

This study is the first to show that longer wavelengths of sunlight can improve human visual function without direct ocular exposure.

The implications are profound:

• Sunlight as Systemic Medicine: Sunlight’s longer wavelengths can reach key organs even through clothing, promoting mitochondrial function and counteracting the decline associated with age and disease.
• A New Paradigm for Vision Health: Rather than focusing light on the eyes, whole-body light exposure may offer therapeutic benefits.
• Rethinking Modern Lighting: The narrow-spectrum LED lighting that dominates our indoor environments may be suppressing mitochondrial function. Broad-spectrum light, including near-infrared, may be essential for optimal health.

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The Mitochondrial Theory of Aging

This research aligns with the mitochondrial theory of aging, which posits that the gradual decline of mitochondrial function drives the aging process. By stimulating mitochondrial activity with light, we may be able to slow or reverse some aspects of age-related decline — not just in vision, but throughout the body.

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Practical Takeaways

• Spend time outdoors in natural sunlight, especially in the morning and late afternoon when infrared wavelengths are plentiful.
• Don’t fear the sun — but do protect against UV overexposure with sensible measures like hats and sunscreen.
• Consider your indoor lighting: Full-spectrum or incandescent lighting may be more beneficial than narrow-spectrum LEDs.
• Red light therapy devices that emit in the 660–1000 nm range may offer targeted mitochondrial support.

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The Bottom Line

The 2025 Scientific Reports study by Jeffery, Fosbury, Barrett, and colleagues opens an exciting new chapter in our understanding of light and health. It suggests that sunlight is not just for vitamin D — it’s a systemic mitochondrial fuel that can sharpen your vision from the inside out.

“Our data show that longer wavelengths of sunlight penetrate through the human body and, consistent with animal studies, have the ability to improve function.”

In a world increasingly lit by screens and LEDs, perhaps the best thing we can do for our eyes is simply step outside.

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Reference: Jeffery, G., Fosbury, R., Barrett, E., et al. (2025). Longer wavelengths in sunlight pass through the human body and have a systemic impact which improves vision. Scientific Reports, 15, 24435. DOI: 10.1038/s41598-025-09785-3