Are You EnLIGHTENED? Pt. 2 With Dr. Glen Jeffery

Adiel Gorel continues his enLIGHTening conversation with leading researcher and expert on the effects of light, Neuroscientist Glen Jeffery, PhD. In this second part of their discussion, they talk about the powerful and free wellness solution you can directly get from natural light, emphasizing the need to go outdoors. He explains how mitochondria act as a community and the ability of plants to reflect infrared light. Dr. Jeffery also breaks down the beneficial effects of red light to the eyesight and the negative effects of blue light, especially during end-of-the-day exposure. Learn how light can make your body healthier and your eyesight better in this in-depth and informative conversation.

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Are You EnLIGHTENED? Pt. 2 With Dr. Glen Jeffery

The Powerful FREE Wellness Solution At Your Fingertips

Step Outside And Take A Little Break

If I still continue with a circadian viewpoint, which doesn’t contradict anything. As Roger Seheult says, he tries to put the patients outside in the yard. They get released a few days earlier. You talked about people in hospitals, the ones that were near the windows, released sooner. By the way, 100 years ago, they knew it. The hospitals have huge terraces where you can wheel people outside.

Still, can we say that if you have an opportunity to step outside, take a little break? They used to call it the cigarette break. That’s not a good break. You get a sunlight break any time of the day until sunset. Rather than staying in the house, especially if you are in front of some screen. That would be a beneficial thing to do?

Definitely. Most days, irrespective of how well my fridge is stocked. Around lunchtime, I take a walk for ten minutes and I go to the supermarket. Why am I doing that? I’m doing that particularly on a day that’s been cold, but it’s sunny. You go out there. You feel the warmth coming through your clothes. That’s the infrared doing it. You feel better. What is a better notion? I know that if you expose people to long wavelength light, you get changes in serum. Some things are changing.

What I want to do, an experiment I haven’t done, is to get you sitting in a grim office, cannulate you, and take blood samples. Take you to the park for an hour where you feel good and start taking those blood samples. What has changed? Everybody feels better. I’m sure my cat used to feel better. I’m sure primordial humans all felt better. That’s a big one. What’s going on? It’s affecting all the organs in your body. I’m going to die not knowing most of the answers to these questions.

I had a professor from Nippon University, who is also working at Stanford, talk about the subject of forest bathing. His lab was trying to break it into the component parts. He said, “You are getting affected. The feeling of well-being can be measured.” They can measure all of your vitals. They can show why you’re feeling better. He said, “There is the vision, the smell you hear, all of those count.” They broke it into pieces.

How The Mitochondria Acts As A Community

Literally, they had people in a hotel room, completely without nature. They put posters of trees on the wall. It made an improvement. They had people in a hotel room. They put the essence of one of the trees in the forest in droplets in the room. It had an effect. Altogether, he says, “It’s all the senses.” We are talking primarily about the visual. It’s not just vision because the light hits our skin. We have a lot of light receptivity in our skin, which by the way, leads me to something else. I jump back to your experiment with the glucose peak. You’ve shown it, if I’m not mistaken on the shoulder.

The light we put was on the shoulder. It was over a relatively small area of the body surface.

It was exposed. Although, the long wavelengths go through the shirt.

The big thing that always people should remember about mitochondria is they act as a community throughout your body. They talk to one another. One of the great experiments done by John Mitrofanis had primate models of Parkinson’s disease. Which happens when you’ve got a small nucleus in your brainstem where mitochondria basically signal cell death. If you put a red-light probe into the brain, he could block the symptoms of Parkinson’s disease. He could do the same when he shone light on the legs and on the abdomen of primates.

Messages get around. We got a big change in blood sugars, only stimulating a small area of the back. The mitochondria in that region sent a message out. They act as a community. They started consuming glucose. I’d love to know how these mitochondria are talking. What’s their language? There clearly is a language. It’s for good and bad. I’m not going to resolve that one. Long after I’ve retired, I hope I’m still alive to read the paper that resolves that particular issue.

It’s terribly important, not only in terms of evolution. It’s terribly important for health. Can we have a person who’s very ill? We expose their feet sticking out at the end of their hospital bed to low level infrared light. Is that enough? There’s a great biological and evolutionary question. At the same time, there’s health implications that are very significant as well.

To take it to practicality, when people hear about your experiment. They assume, “He took off their shirts. He shone the light on their shoulder.” Again, remember everyone. That light, the infrared light, long wavelength will go through your shirt. It doesn’t even fill your shirt. You can go outside. Basically, a good practice if the weather lets you do that is to have your meal outside.

I walked out and I wore a coat. If you can feel warmth, that is long wavelength light coming through your clothes. If you choose to wear something ridiculous like rubber, maybe it won’t. We did this with Bob Fosbury. He emptied his wardrobe. He started lining up clothing. Putting different lights behind it, photographing it as published. You take something like 670 nanometer, 850 nanometer comes through. If you’ve got an infrared camera, you can photograph it.

That’s something to remember. Being outside is a good thing. Some people say, “I don’t want to eat outside. It’s too hot.” I heard Alexis Cowen say, “Use nature’s sunscreen. It’s called shade.” You see a lot of people. You talk about feeling good. You go to the park. You eat your meal in the shade but outside. Don’t you feel good?

How Plants Reflect Infrared Light

You do. There is something also quite important here which is something we’re just moving through. Which is, we know that plants reflect infrared. Bob’s a big proponent of this. Bob said, “We’ve known that for ages.” He keeps saying we’ve known that for ages. What we did is we started putting radiometers measuring the energy in long wavelengths on those plant leaves. The energy that they are producing just beyond the surface of the leaf is within reach of a therapeutic dose that we know we can use to improve vision.

I find this intriguing. As we were working down and down with our powers, someone in the lab said, “We’re close to what we were getting off a single leaf.” What happens when you’re standing surrounded by a tree? This notion of bathing in nature. If you asked me that in 2021, I’d have walked out of the room. As with so many things in science, you get it wrong many times before you get it right.

There may be a significant story in going for a walk in the park. This summer, we’re going to be working very hard on different plants’ reflectivity. How much are they reflecting? Are any of them lensing this? Can you lens it with the different shapes of leaves? It’s about bringing science almost into the realm of myths that have been around for many years about what certain things are beneficial and what certain things are not beneficial. I’m looking forward to that.

I finished a grant application. It was great. That’s over. I finished filling in 53 boxes, putting numbers and figures, and everything. I hated every minute of it. Do you know my reaction? I walked down the corridor earlier. I said, “I finished. I’ve had it. I’m not doing it anymore. We’ve got plants sitting outside in the office. That’s where I’m going to be in the morning.” Sorry, that was a little rant. That’s interesting.

You can see that even people without researching deep, without doing experiments like you do. When people are building places. They intuitively create a pleasant little courtyard for people to sit and eat. There are trees around it and greenery. If you go to the fancy neighborhood, one of the features of a fancy house is a lot of green, a lot of trees. That usually is a good thing. Everybody looks for green. Again, to simplify it for the readers, just be outside near a tree. Sit down. Read a book by the tree. Be outside.

I completely agree with you. Experiencing the outside. There are so many reasons for this to be good for health. There’s no money in it. No drug companies are ever going to make any money out of this one. A few lighting engineers make some money out of it. They’re not going to make much but public health. Outside is where you’ve been for four or five million years. All life has evolved under sunlight.

We’ve done something radical in terms of our light experience. It’s driven by evolution. One of the things I’m quite obsessed about is water absorbing red light. It’s why the oceans are blue. We have this long period of evolution in the sea before animals developed and came onto the land. Two things happened when they came onto the land.

First of all, suddenly, they got bombarded with a vast amount of infrared because they’re no longer in water. Secondly, they were surrounded by plant matter. I’ve got no proof or evidence of anything here. The thing that I would love to believe is those animals that were under the water. The water probably wasn’t very clear.

Those animals were getting a restricted spectrum of light. They were getting far less infrared. When you come out, you’re suddenly getting a vast amount of infrared. You’re surrounded by plant matter. At that point, there is quite a kick in evolution. Did it have something to do with infrared light and that animal’s transition? There are some big pictures in it.

Beneficial Effect Of Red Light On Eyesight

That’s a fascinating and logical thought that somebody should explore. It makes a lot of sense. I’m going to jump to your eye work. You do a lot of work with the eye, with vision, the aging eye and how to make it better. I heard you say something interesting. You’re talking about the beneficial effect of red light. By extension to our conversation, probably the longer lights as well, on the eye. I heard you say that it does not work gradually. It works like a switch. If I recall correctly, you said the minimum amount of time that you need is about 75 seconds.

About a minute. Let’s say a minute to a minute and a half. It’s one of the reasons why lots of the medical profession find this hard to believe because they always think in terms of a dose response. There is no dose response curve. It’s not in flies, mice, or humans. It’s not in this experiment. It’s not in that experiment. This is why we’re working down and down in energy. We’re still getting this response. If you’re below that point, nothing happens.

It’s a clear-cut threshold.

There is a threshold there. The threshold is surprisingly low. Two things happen. One is we make all our energy with a pump that goes round and round in circles. The faster it goes in these mitochondria, the more energy you produce. We give a certain amount of energy and kick. The rotor starts spinning faster.

As the rotor starts spinning faster, something else kicks in. That is where we start making more pathways to make energy. It’s called the electron transport chain. We’re making more of them as this thing gets faster. It is a switch. It’s also not only a switch on the on-side. It’s a bit of a switch on the off-side. Because if we use just, say, 670 nanometer light, we get the switch. Five days later, it goes.

One thing that I liked, you have the same approach in your mind that I happen to have on this show. Make it so simple for everyone to do. I heard you say, “Go on with your lives. Go on.” You don’t want people having all kinds of lists. When did they do that? What you said, “Let’s play it safe. Let’s do three minutes daily.” You don’t have to think about, “Did I do it three days ago? I know it lasts for five days.” You said three minutes daily. What you’re talking about, I believe, is red light into your eyes. How are you looking into it? Is it on a tangent and bouncers? How did you do that?

To go around the corner a little bit. I can put that light on your shoulder. I can wrap your head in silver foil so you cannot see it with aluminum foil. Your vision still improves. There are different pathways here. With humans and with animals, what we have done, and this has involved a lot of biomedical engineering.

When mitochondria work hard, they change color. Quite interesting, they change color. If you look at the mitochondria with an expensive spectrometer, you can see them working. We’ve watched them working. We’ve shone light into the eye. We’ve watched the mitochondria themselves changing color. You can see it.

Secondly, if it’s an animal, we can take that eye out. We can just simply measure what the mitochondria are doing after they’re exposed to different lights. The great tool that I have is because of my background. There’s very little between the mitochondria in your eye and the outside world. The light comes straight. The great thing about the visual system is I can just say to you, “Can you see that now?” It’s because you couldn’t see it earlier.

I’ve got a simple way of testing it. We use color vision because it’s simple. It’s quick. We’ve got the equipment to do it. We know after three minutes of long wavelength light exposure, your color vision improves. If we do that with an animal, we take their eyes out. We look at the mitochondria. We can see how the mitochondria have changed. There’s more energy. They are different and likewise, we can watch them in real time.

It’s not particularly difficult to see how they change color. You can take a worm. You can pin a worm out. You can make a worm move. You can watch its mitochondria change color by putting a spectrometer on it. If I had been working on the foot and been working on red light, I would have been challenged to find easy metrics. I can go into a room. I can change a light bulb. I can take you back and say, “I show you these colored letters on noisy backgrounds. Can you see it now? You couldn’t see it in the morning.”

What about visual acuity? You put somebody in front of a chart that the optometrist would have. They can only see up to line 4. Whatever line 4 is. You give them the red light for three minutes. Will they see line 5? Are they more likely to see line 5?

They’ve claimed it. We are doing visual acuity. It’s looking pretty good. If you want to do this, you don’t use lines on a chart. You use black and white bars. You make them smaller and smaller until people can’t see gratings. Until you can’t see it or you change their contrast. The other one that’s out there, people have not picked this up.

In one of our failed clinical trials, we took ladies with macular degeneration. The control group were their partners because they’d eat the same food. They had the same lifestyle. We measured them doing a whole range of things. Both groups had red lights. The dark adaptation times improved significantly in the control group at the red light. That means, for you to adapt properly, it’s age dependent. It is 40 minutes. Get older, 45. You’re young, 25. It’s very clear that dark adaptation times improve.

That’s significant for a whole series of reasons out in the real world. We have some pilots from a major airline say to me, “We’re older guys. We’re in our late 50s. We’re costing the airline a lot of money. When it’s at night and it’s snowing or it’s raining heavily, I’m not sure I’m seeing things in quite the way I should do.”

They’re tending to hand over landing in the aircraft to their much younger co-pilots at that time. We had a long discussion with the pilots there because they were switching the cabin lights out for something twenty minutes before they landed. Even the young co-pilot wasn’t fully dark adapted. We’ve had another thing where we ran an investigation into a shipping accident that resulted in some people being killed because a massive ferry ran into a yacht.

The reason it did was that the people on the bridge that should have been watching what was going on were in and off the bridge. Off the bridge, there was light. It was at night but there were lots of lights on the deck. We know we can improve dark adaptation. Dark adaptation is one of the most energy consuming events in your body because as you turn the lights down, your retina goes, “I can’t see this. I’m going to burn more energy to find it.”

It’s like turning the amplifier up on your stereo system. That’s a clear winner that people seem to have missed out on, dark adaptation functions. We can improve color vision. We can improve dark adaptation. If you come and talk to me in a month’s time, I’ll give you the exact figure for what we’ve done with acuity.

Even the dark adaptation, if you look at the primitive world maybe a few hundred years ago. Dark adaptation could mean the difference between life and death.

When are you truly dark adapted? You’re truly dark adapted in our world when you get up in the middle of the night, go to the toilet, and keep your eyes closed. Dark adaptation is a relatively rare event in the modern world. You go past down the street, car lights, street lights, telly at home. You switch the light off just before you go to bed. You’re never dark adapted.

It’s interesting. I have, for years, been sleeping in a completely dark environment. I have those shades that are very thick that fall down. Everything. I’m sleeping in a cave, turning off everything. When I go to go to the bathroom in the middle of the night, I still realize there’s one thing I didn’t do. The people who installed the light switches in my bathroom thought that they should shine a little bit of a light.

When you do that, your retina reacts. “I’ve got a signal.” It stops burning energy. Mitochondria stops working so hard. I’ve got a signal.

I don’t know if it was a valid experiment. It was an experiment where they shone a little flashlight on the back of the knee in the middle of the night. I don’t know if that was a valid experiment.

I don’t either. It’s a circadian thing. I’ve heard the circadian people can be quite caustic about it. I don’t know if that’s correct or not.

I’m still going to ping you on this thing with the 3 minutes or 1 minute or the 5 days, all of that. When you were applying the red light, how were you doing it? Physically, where? Into the eye, you look into it? What were you doing?

In those experiments, which were some time ago, even though it was only published maybe in 2023. We were putting people in front of a series of LEDs that we had produced.

Did they have to look into the LEDs, scans?

It was in their visual environment. There’s a company. I don’t have financial interests in them. They make red light glasses. Testing those red-light glasses, which are LEDs, it’s very interesting. It didn’t make too much difference whether your eyes were open or closed. Those long wavelengths just go through. When we use them in trials patients say, “Should I keep my eyes open or eyes closed? We just say, “Whatever is most comfortable for you.”

Why Going Outside Is A Non-Negotiable

Going back to the beginning of our conversation and tying these two points together. Let’s say that I want to be a good soldier. I want to use three minutes a day, every day, even though it’s for five days or whatever. Should I just go outside?

You should. You and I know that.

I’m done then. I don’t have any obligation to do the red light because the red light is out there. Much better than a red light.

We only said every day because a lot of the projects we were doing were with elderly people. They were never going to remember when they did it, on your Tuesday last or Thursday.

I don’t remember.

I’m in 100% agreement with you. In evolutionary terms, we’ve got ourselves in a very difficult position in the built environment. We spend more than 90% of our time here. We have very bad lighting. You need to go outside. Even in winter when it’s cloudy. The infrared isn’t focused anymore because it goes through clouds. It all gets scattered. There’s still loads of infrared out there.

For me, it’s a walk to the supermarket at lunchtime. Whatever the weather, I cycle to work. Maybe I’m doing that for cardiovascular reasons as well, but it’s my outside experience. That’s half an hour in the morning and a little bit longer in the evening because it’s up the hill. It’s part of a pattern that I subconsciously have adopted to make sure I get plenty of sunlight.

I heard Bob Fosbury once say something that was unusual. You guys were talking about UVB. They say in some parts of the world, depending on your latitude, a good portion of the year, you can’t make UVB. You can go outside. He said, “Not so. Even in the winter, there’s plenty of UVB scattered in the clouds and from the clouds.” The reason though, UVB is so short. Your clothing stops it. In the winter, you’re cold. You’re covered up. You don’t get it. In theory, I found it fascinating. If you walk around bare or naked or half naked, whatever it is in the winter, you can still make vitamin D. That was fascinating to me.

One of the things my clinical colleagues tell me, we’ve got a developing problem with rickets, which is a bone abnormality. Abnormal formation of the bone in some kids in communities in London. When these started turning up, a lot of the clinicians didn’t even recognize it. Again, it’s thought that it’s wintertime. Lots of clothing, covering your body up, not going outside. There’s a debate going on about why we have this Victorian disease, which is how it’s perceived, suddenly turning up again. Bob’s right. Basically, again, it’s about getting outside.

Again, we’re talking about the short wavelength. The shirt is even going to block it.

This is a North European problem. This is a North European issue. Fundamentally, humans shouldn’t be this far north. We’re out of phase with so many things.

Don’t you think it would be exacerbated if somebody from the equator region who has a heritage and grew all their life getting copious amounts of sun? In fact, their skin has the melatonin to show for it. They move to London, won’t they even have it worse?

One of the things I want to do, and I’ve said quite openly, is we’ve had all these great successes with long wavelength light. Great successes. The only reason we’ve had them is because my subjects, whether they be animals or humans, are all inside suffering from a shortage of sunlight. In the summer, I want to start testing people in the UK who are getting a lot of sunlight.

Is it the case that I can’t improve their vision very much? Is it the case that we know that people who spend more time in sunlight have much better control over their blood glucose levels? It’s all pinned down to our bricks and our concrete particularly in wintertime. I’m going to do that experiment this summer. If I was to go to Egypt, I wouldn’t be getting any great results I’m sure of it.

By the way, talking about spending those 3 minutes or 2 minutes a day out in the light. Both you and I are wearing glasses. Those lenses probably were treated to block certain frequencies. I would assume it would be best to take them off.

It would do but there’s this whole systemic response to light. Since there’s a systemic response, I’m not too worried about it. We spent a lot of time a few years ago looking at filters on glasses and what they would do and, in the end, I said stop. We’re not getting anywhere here.

Why Blue Light At The End Of The Day Is Very Bad

I want to jump to a circadian point. It dovetails into all that we’ve been talking about. The sun has set. It’s dark. Again, hundreds of years ago, we just went to bed. There was a candle, something, whatever. Now, “This is exactly the time. I’m done with work. I’m free. Let’s check the news on my cell phone. Let’s go on my laptop. Let’s go into the blue in isolation light sources.” We know very well that just even on the circadian point of the pure blue light telling here that it’s midday. It’s noon. No, but it’s 10 PM, destroying a lot of the good stuff for sleep. Number one, would it make sense to wear good, well-made, blue blocking glasses?

That’s what we tried but it didn’t work. That makes so much sense. It makes a lot of sense. There’s about four or five labs that have tried this. We have not got a big effect. It’s very variable between individuals. Big problem with humans. They’re so variable. Mice are great because they’re all the same. It needs a very big study to do it.

You’re right, particularly later in the day. Exposure to blue light is very bad news. There’s a major American computer company that came to us with this problem and said, “Do we need to change the color on our background screens?” I said, “That would be a superb idea.” The screen engineers were up for it. The conversation went on for a little while. It was passed down the chain in the company. We say in England, it went down like a lead balloon.

It just does firstly because I was told it consumes a little bit more energy. Secondly, I was told that and it all came from sales. The good thing about the blue screen, generally as a generic feature, is the fact it stresses you a little bit. All your employers want you stressed a little bit to pay attention. With a blue screen, there are over large groups of people. There’s a slightly higher level of cortisol. We could measure that slight stress. It doesn’t matter what arguments we made. Sales blocked it.

We’ve had similar discussions with mobile phone companies. Similar arguments have come out, which is the cost of generating the red light as compared with having a blue light device. I’m not an engineer. I don’t know. That’s a consistent story we get back. Completely, I would avoid blue light late in the day. I know both my kids avoid blue light late in the day. The filter thing, there is something in there, but I’ve not been able to dig it out.

Going with your reminding me that whether we wear glasses or not, it doesn’t matter because we absorb light in many other parts of our body. Even if you wear the blue blocking glasses and if they do that, they are colored orange. Good, but this is only here. What about here?

What about around the sides? It could be a small amount of blue light coming around the sides that undermines the whole project. We don’t know that.

You’re talking about the much bigger problem. For a human being, to deny themselves of television, deny themselves of the computer, the phone. The minute the sun goes down, that has to be a very strong human being.

I completely agree with you. This is a problem we’re not going to solve. Maybe we can manage the edges of it. It’s a very big issue. I completely agree. We’ve taken a few bites at it. We haven’t got very far.

What about intensity? Normally, the human body is probably used to lights being dimmer. Dimmer than fire and reddish candles. Here we are at home, even if we have incandescent lamps. You keep talking, and rightfully, about low intensity, 40 watts, small. If you have 100 watts. It’s incandescent light. It’s the good stuff. Still, it’s bright light. Probably not great for a system at night, is it?

No, but also think about how it’s very bright. If we’re out in sunlight, it’s distributed. When you’ve got your 100 watt or 60 watt light bulb in your sitting room that light is not only going out. It’s bouncing back and coming around. When we started putting even 40 watts light bulbs in without the demos, they were a little bit sharp. Having your lights inside and incandescent, which is great. I push that point. Turn them down. In your domestic environment, there is so much light bouncing around. You don’t get rid of it. Whereas in sunlight, it’s distributed all over the place.

You can use a dimmer. By the way, I heard you speak about Ott. It’s still the company that sells light. They call them full spectrum light, which mimics the sunlight. If you use it at night, it’s very bright.

I’ve never got a hold of an OttLight. The video is outstanding. It’s outstanding for its time and for its anarchistic nature. Here was a chap who was thinking about things before his time. A lot of it was very weird. There are some absolute gems that I think are terribly important. I very often give that video to people and say, “Watch this video.”

It starts out in the most weird way. It bounces around all over the place. He was a cinematographer for Kodak. He was a little bit out of his depth. He didn’t understand too much about wavelengths. His main stuff were slow frame photography, cinematography. All my graduate students have to watch that film. They all enjoy it.

I don’t think I’ve seen that film. How can I find it?

Probably, type in “Ott Light Video.” If you can’t find it, shout at me.

There is one thing that I hear a lot of people talk about, including my own kids. We know that the blue light that comes from our devices is not very good at night. My kids and many other people will tell me, “No problem. I have nightlight on my phone. It gets to be yellowish and I’m safe.” Dr. Moore-Ede told me the horrifying thing that they only paint it superficially. The driving light is still blue. It doesn’t make you any safer.

There’s a lot more blue around than you know about. Nearly all LEDs are fundamentally blue devices. They generate a blue light that falls onto a phosphor that produces other lights. I didn’t know that about phones. If he says that, I believe it. He knows a lot about light. I’m not desperately surprised. Whatever they do, it will be the cheapest route around something.

You see, that’s very dangerous because billions of people, literally billions, are under the false impression that they’re safe. They said, “Nightlight on. It looks a little yellowish. I’m all good.” Apparently, they’re not good at all. The glasses will protect your eyes. As you pointed out, what about all the other stuff?

The glasses remain an enigma.

Discussion Wrap-up And Closing Words

Glen, I want to thank you. If I haven’t been stifling myself a little bit, because I know it’s a little bit late for you. We could have been here for five hours. I love the way you think about all of that stuff. Again, “Do this simple thing and go on with your life.” I love that. Thank you so much for the great information. I enjoyed it very much.

Thank you because we need to get the story out to people. It’s an issue of public health. I’m very happy to chat. Thanks very much.

Important Links

• Dr. Glen Jeffery on LinkedIn
• Bob Fosbury on LinkedIn
• University College London
• OttLight

About Dr. Glen Jeffery

Dr. Glen Jeffery, PhD, is a professor of neuroscience at University College London of Ophthalmology and a leading expert on how different colors (wavelengths) of light impact cellular, organ and overall health. His research focuses on how light exposure affect the retina and mitochondrial function. He has pioneered studies showing how specific wavelengths of light, including red and infrared, can improve visual performance and support healthy aging of the eye. His work bridges neuroscience, ophthalmology, and environmental health, emphasizing practical, light-based approaches to protect and restore vision.