For decades, eye care advice has centered on screen breaks, blue-light filters, and annual checkups. But according to one of the world’s leading vision scientists, the single most powerful thing you can do for your eyes might already be right outside your window.

Glen Jeffery, a neuroscience professor at University College London who has spent decades studying the human eye — publishing in top-tier medical journals, advising governments, and training a generation of vision scientists — says the answer is daylight. Jeffery practices what he preaches: he commutes to work by bike, in part because of what sunlight does for his retinas.

“Without doubt, the best kind of light for your vision is daylight.”— Glen Jeffery, Professor of Neuroscience, UCL

The Light We’re Missing

Most of us are starved of one critical component of natural light: infrared wavelengths.

Two factors are driving this deficit. We spend far less time outdoors than we used to, and most indoor lighting today comes from LED bulbs, which are designed for energy efficiency rather than eye health. LEDs emit plenty of visible light, but they strip out infrared almost entirely.

That matters because infrared light does something no other wavelength does as effectively: it penetrates the skin and boosts mitochondrial function, which in turn increases cellular energy production (ATP). In the eye, that ATP helps regulate eye pressure, maintain the lens, and protect against retinal cell damage — offering meaningful protection against glaucoma, cataracts, and macular degeneration.

The retina is especially vulnerable to age-related decline because it contains an exceptionally dense concentration of mitochondria and runs at a high metabolic rate. Infrared wavelengths appear to help recharge it.

In one of Jeffery’s studies, published in Scientific Reports, infrared light applied for 15 minutes to the chest — deliberately kept out of the eyes — significantly improved color contrast sensitivity, a measure of retinal function nearly as important as visual acuity. It is what allows us to distinguish objects from their background, which matters for driving, reading, and daily life.

A follow-up study gave office workers broad-spectrum incandescent lamps that included infrared light. The result: significant improvements in color contrast sensitivity that lasted two months. Researchers believe this reflects a genuine boost to mitochondrial performance. A separate study, also in Scientific Reports, suggests that a simple, low-cost intervention — like placing a small incandescent lamp nearby — could meaningfully offset age-related declines in ATP production.

“I can make it sound really impressive and high tech, but it’s not.”— Glen Jeffery

His research points to something almost old-fashioned: incandescent light shares the same wavelength profile as sunlight, unlike LED light. Sunlight is simply more intense and more balanced — even on a cloudy day.

Why Children Are the Most Urgent Case

The case for daylight begins in childhood, with the prevention of myopia (nearsightedness).

Myopia is not just a matter of blurry vision. It is a medical condition that raises the lifetime risk of complications like retinal detachment and glaucoma, according to the National Academies of Sciences.

~60%
Myopia risk with two nearsighted parents
~20%
That risk with 14 hrs/week outdoors
~40%
Of Americans now myopic — and climbing

Sunlight is the primary strategy for preventing myopia, says Donald Mutti, an optometry professor at Ohio State and co-author of the National Academies’ report on the condition. It is powerful enough to offset strong genetic risk: children with two nearsighted parents have roughly a 60 percent chance of becoming nearsighted themselves. But spending 14 hours a week outdoors can cut that risk to about 20 percent.

The catch, Mutti notes, is timing — sunlight exposure cannot reverse myopia that has already started progressing in a child. The likely mechanism is dopamine: bright light triggers its release from retinal cells, which appears to stop the eyeball from growing too long.

Roughly 40 percent of Americans now have myopia, and the number is climbing. “I would put the blame on being indoors, which is just more fun than it ever used to be with screens and video games and entertainment options,” Mutti says.

One caution from Jeffery: don’t substitute infrared light devices for real sunlight. Most commercial devices he has reviewed are far too powerful, and because energy output varies widely across products with little regulation, exposure time becomes hard to judge safely. Manufacturers tend to chase stronger, brighter, more intense — even when the research has not caught up to justify it.

Bottom Line: Don’t Fear Sunlight

The practical takeaway is simpler than it sounds.

Outdoors, you do not need direct sun exposure to benefit — you should still protect your eyes from ultraviolet light with sunglasses, a hat, or shade, Mutti says.

Jeffery currently recommends at least 30 minutes of outdoor time daily, though he notes that guidance may evolve as research accelerates.

If you are indoors, Jeffery suggests adding a single incandescent or halogen bulb — both of which include infrared wavelengths — in a spot where you spend time in the morning. Morning light exposure matters most, he says, whether it comes from outdoors or an artificial source, because mitochondria are more responsive right after waking.

Jeffery hopes to shift conventional thinking — and the laws that limit incandescent bulbs — by sharing his research with policymakers and architects.

“I’m not saying that it’s all got to do with light, but I think we should start paying attention to light.”— Glen Jeffery

Credit and Sources

This post is adapted from reporting on the work of Dr. Glen Jeffery, professor of neuroscience at University College London, and Dr. Donald Mutti, professor of optometry at Ohio State University, as originally covered by The Epoch Times. Full credit for the original research and interviews goes to those researchers and that reporting.

Referenced studies:

“There are in fact two things, science and opinion; the former begets knowledge, the latter ignorance.”— Hippocrates