AMA #6: Eye Health, Why We Yawn & Increasing Motivation

Andrew Huberman (0:00)

welcome to the Huberman Lab podcast, where we discuss science and science-based tools for everyday life.

I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today is an Ask Me Anything episode, or AMA. This is part of our premium subscriber channel. Our premium subscriber channel was started in order to provide support for this standard Huberman Lab podcast, which comes out every Monday and is available at zero cost to everybody on all standard feeds, YouTube, Apple, Spotify and elsewhere. We also started the premium channel as a way to generate support for exciting research being done at Stanford and elsewhere. Research on human beings that leads to important discoveries that assist mental health, physical health and performance. I'm also pleased to inform you that for every dollar the Huberman Lab premium channel generates for research studies, the Tiny Foundation has agreed to match that amount. So now we are able to double the total amount of funding given to studies of mental health, physical health and human performance. If you'd like to subscribe to the Huberman Lab podcast premium channel, please go to hubermanlab.com/premium.

It is $10 a month to subscribe or you can pay $100 all at once to get an entire 12 month subscription for a year. We also have a lifetime subscription model that is a one-time payment. And again, you can find that option at hubermanlab.com/premium. For those of you that are already subscribers to the premium channel, please go to hubermanlab.com/premium and download the premium subscription feed. And for those of you that are not Huberman Lab podcast premium subscribers, you can still hear the first 20 minutes of today's episode and determine whether or not becoming a premium subscriber is for you. And now without further ado, I will answer your questions. And as always, I will strive to be as thorough as possible, as clear as possible, and as concise as possible. And the first question is about eye health, in particular, eye health protocols for people that are aging, but eye health protocols for people in general. The question is, I'm noticing that my vision, both close and far, is deteriorating. What are the best eye exercises, eye health behaviors, supplements, et cetera, for the aging eye? So the answer I'm about to provide applies to everybody, regardless of age, which is, you want to make sure that you view things both close up and far away across your day. Many, many people nowadays spend a lot of time looking at their smartphone, looking at the computer screen, looking at books and paper. In other words, looking at things somewhere between nine inches away from their face and their eyes, maybe two and a half feet away from their face and eyes. This is an unprecedented event in human history, as far as we know, because it wasn't until the advent of the smartphone that we've spent so much time looking at screens at close range relative to looking at things at further distances from our face throughout the day. In fact, it should come as no surprise that the incidence of myopia, of nearsightedness, is increasing dramatically around the world, but is increasing particularly fast in children and in young adults and even in adults who are viewing things at very close range. So two and a half feet or less. Now, I am not saying that viewing things at two and a half feet or less is bad for your eyes. That is simply not the case. However, if you want your vision to be maintained or even improve, it's going to be very important for you to view things at a distance as well, for ideally several hours per day. I realize some people just simply won't accomplish this. In fact, I'd like everyone to just take a moment and do a rough estimation in your head of how much time during your daytime activities you are viewing things at say two and a half feet or three feet or less. So smartphone, computer screen, paper, books, et cetera, versus viewing things that are four feet away, eight feet away. So maybe conversation across a table with another human being, remember those. Some of us are doing that more now that we seem to be emerging from this whole pandemic phase. However, many people are still mostly just viewing things within very close range. And in fact, if you were to ask yourself, how much time do you spend looking at things at the distance of many hundreds of feet, or taking a walk where you're not looking at any screen and you're simply letting visual images or the visual imagery rather pass by on your eyes. I think for most of us, that number is getting progressively smaller and smaller with each passing year. So this is an issue because the structure of the eye is such that the lens of the eye can move, but also that the length of the eyeball from front to back is actually impacted by how close or how far you happen to view things during the course of your day, especially during development. There's a classic experiment that I'd like to just briefly describe to you, which has been performed in chickens, it's been performed in mice, it's also been performed on humans, where a visual occluder or a visual image, so an occluder is just a black sort of screen or piece of cardboard, or an image, maybe some black and white checks or checkers are placed at a certain distance from the eye, either up close or far away. And the impact of that on the length of the eyeball and on the structure of the lens and on the quality and acuity of vision is then measured. And to make a long story short, what these studies show is that if during development you or an animal exclusively looks at things that are up close, very close to the eye and doesn't ever get long range vision, the eyeball lengthens. When that happens, the lens, which of course is in the front of the eyeball, which focuses the light onto the back of the eyeball, which is where the so-called neural retina is, where the cells that sense light are, that visual image lands in front of, as opposed to directly on the light-sensing portion of the eyeball, that we call the neural retina. It lands too close or near the lens, as opposed to on the back of the eyeball. And that's part of the reason what we call the consequence of that near-sighted myopia. In far-sightedness, the opposite happens. The visual image is actually focused behind the retina. It doesn't land directly on the retina, which is what you want. It's focused too far behind the retina, and that's due to a shortening of the eyeball. So what I just described actually explains pretty well why kids who look at computer screens or books up close often need glasses. You know, when I was growing up, they called this nerd syndrome. Raising my hand for those of you that are listening. I read an awful lot, but I also spend time outside fortunately and running around on the soccer field and looking at things in the distance and playing in the neighborhood with my friends. Kids that spend the vast amount of their time looking at things up close, in particular children who do that indoors for most of their waking time. Well, those kids develop myopia. This is part of the reason why we have such an increase of the incidence of myopia nowadays. What's interesting and I think most people don't realize is that even as a young adult and adult, and perhaps even as an older adult, an elderly person, looking at things up close too much at the expense of getting some time viewing things at a distance, in particular outdoors, can be very problematic because it can exacerbate myopia. So the short direct prescription here is to make sure that you're getting at least an hour or so each day, although ideally it would be more of long viewing. And that could be done by walking outside and avoiding looking at your phone while walking. It doesn't require that you look at a particular object in the distance, although if you are scanning for and looking for objects in the distance, the way that you might on a hike or you're looking out toward or off a vista, you're looking for someone in the distance, all of that sort of visual scanning behavior is going to be very good for your eye health and for maintaining vision at a distance. If you're somebody who's farsighted and you have trouble seeing things up close, well then you need to ask yourself whether or not you're spending too much time looking at things off in the distance. Although I want to be very clear that nearsightedness and farsightedness aren't necessarily the consequence of this near far viewing. There can be independent causes of nearsightedness and farsightedness. But for many people out there who are spending progressively more and more time just looking at things up close, you can get this lengthening of the eyeball or challenges in the way that the elasticity of the lens is controlled by the musculature in ways that make it hard to maintain sharp, crisp vision when you are looking at things at a distance or up close. Okay, so I can't because there are simply no studies to support the idea that you need exactly two hours per day of outside long vision in a particular distance and where that you want to cut off or have a threshold of, you know, four hours per day of looking at things up close. But we can say with a high degree of confidence that if you want to maintain or enhance your vision at all distances, that for every hour or so that you spend looking at things, say, a distance of three feet away or less, you want to get at least one hour per day total, doesn't have to be all at once, of looking at things out in the distance or looking at things beyond three feet relative to the distance from your eye. Okay, so I think for some people who are already badly myopic, this isn't going to remedy that myopia. You're still going to need corrective lenses. But if you're somebody similar to the person who asked the question that they're quote unquote, noticing their vision is deteriorating, really try and balance out the amount of viewing that you're doing at close distance and long distance. And again, I would not obsess about the total numbers. You know, it doesn't have to be three hours and three hours. But the more time that you can spend at viewing things at variable distance throughout the day, the better off you're going to be in maintaining and perhaps even enhancing your vision somewhat. Now, there's an additional behavioral tool that we can glean from the recent scientific literature, Exploring Myopia, which points to the fact that children who get two hours a day or more of time outside in sunlight, one of my favorite topics, I know many people are probably rolling their eyes right now. When they hear me say, you really want to view morning sunlight, not through a window or windshield, don't wear sunglasses for that, trying to get as much sunlight as you can in your eyes early in the day, never stared at any light so bright, it's painful, look out, et cetera. We've done a lot of episodes on this. We have a light for health episode. This is in all the sleep episodes. It's just such a basic foundation of circadian rhythm and health that I just keep repeating it. However, there are also large scale clinical trials involving thousands of subjects. They have shown that people, children in particular, who get two hours or more of outside time every day have a much lower incidence of myopia. Now, what's really interesting about these studies is that while some of those kids are looking at things further off in the distance than they would if they were indoors on their tablets or screens or with their nose in a book, it does not seem to be the case that they have to be looking at things in the distance in order to see this reduced incidence of myopia. What's probably happening instead is that the particular wavelengths of light that emanate from the sun, that photon energy in particular is triggering the activation of the so-called intrinsically-sensitive melanopsin retinal ganglion cells, which we know are important for setting circadian rhythm, for enhancing mood focus and alertness during the day, and enhancing the quality and duration of sleep at night. But those melanopsin intrinsically-photosensitive ganglion cells are also involved in networks within the eye that relate to blood flow, that relate to the ciliary body, which is a structure within the eye that controls the aperture and movement of some key components within the eye, that also relate to the crispness of vision, that is the acuity of vision at both short and long range. So there are a lot of technical details there. In fact, I really hope to get the great Russ Van Gelder, or Dr. Russ Van Gelder, who's the chair of ophthalmology at the University of Washington in Seattle, who is a world expert in this and the various aspects, both molecular and structural of the ciliary body and the lens, and he's an expert in uveitis, a very interesting topic in its own right, to come on to the podcast and talk more about eye health, and we will do that in the not-too-distant future. Meanwhile, if the first behavioral protocol for enhancing and maintaining eye health is to make sure that you're spending at least some time balancing out the near vision and far vision during the day, it also stands to reason that you want to get outside for at least two hours a day, which I know sounds like a lot, in order to prevent myopia if you're a young person and offset the progression of and maybe even reverse some myopia. We don't know yet based on the data, but there's some indication that's possible by getting outside two hours a day. And the cool thing is, because many people, including myself, have a lot of work to do and we need to be on our phones quite a lot, or we choose to be on our phones quite a lot, this effect of getting sunlight outdoors during the daytime for two hours or more does not seem to require that you stay off your phone or tablet or that you're looking at things far in the distance the entire time. What this means is if you can get outside onto a patio or a deck or an outdoor table if you can, if weather and conditions permit, and do some of your phone time and computer time and reading, et cetera, outdoors. Now, if you're already making an effort to get outside, hike, play sports, take walks, et cetera, that of course counts towards this two hour threshold. And I know this sounds like a lot, this two hours, and yet for most people, it certainly will vary depending on time of year. But I think striving to get on average about two hours of outdoor time, as much as you can, or opening a window, which wouldn't be as good as getting outside, but opening a window and trying to get some natural light exposure to the eye to trigger the activity, these intrinsically photosensitive melnox and retinal ganglion cells, that's going to be a really good idea in trying to offset and maybe even reverse some vision loss. Now, the other behavioral protocols, which have shown to be useful in terms of maintaining or improving vision, relate to the musculature around the eye and the control of the movement of the lens and actually the lens of the eye has its own kind of flexibility. It's a really, really interesting structure. I'll geek out on this far too long if I don't prevent myself from doing so, but the lens is just incredible. The fact that it has a specific structure of proteins like crystallines and things of that sort, and that it can still derive nourishment from blood flow but does not actually have vasculature within it. So it's not, if you've noticed, I mean the lens of your eyes and filled with blood vessels and capillaries because it needs light to pass through. Super interesting structure. I think the only violation of what I just said is the manatee. All right, those big sort of underwater elephant like creatures that I think were or are endangered down in Florida. They were getting chopped up by speed boats, but I think now there's some effort to preserve those big gentle giants. The manatee, as I recall, has a vascularized lens, which is why their eyes look opaque. It looks like they have cataracts in any case. You're not a manatee. You have no blood vessel supply to the lens. Keeping that lens clear is vital. Nowadays, they can do lens replacement. There's really pretty incredible progress in the realm of ophthalmology and surgical replacement of the lens or the cornea, other aspects of the eye. But if you're somebody who is interested in maintaining your vision, you're going to want to maintain the musculature that controls the movement and the change of shape in that lens and the movement of the eyes, which allows you to transition your vision from very sharp when viewing things up close to very sharp when viewing things at a distance. And this is where some of the so-called near far exercises can be very useful. So when we did a full length podcast on eye health and improving eyesight, which I invite you to listen to if you like, talked about two different types of vision exercises that have been shown to be useful for improving vision at the level of acuity that have a lot to do with improving the musculature and the movement of the eyes and the lens. And that's what's called a smooth pursuit task. So you could go on to YouTube if you like and put smooth pursuit eye task and do this for a few minutes each day if you're trying to keep your vision strong. And what that task involves is as the name suggests, smoothly tracking a small dot or crosshatch or arrow on the screen, which is very different than the so-called saccade type eye movements that we often make. Saccades are when you dart your eyes to a particular location to look at something, then dart it to another location to look at something. Micro saccades are little tiny versions of those that we're doing most all of the time, believe it or not. When you look at a visual scene or image, if you did not have those little micro saccades, your brain would adapt or would attenuate to whatever you were looking at and the visual image would actually disappear, which really speaks to how important it is that your perceptions change in order to maintain them. This is very similar to where if something is placed on your hand, say a finger, you'll notice that change. But then if you leave it there for a short while, you'll forget that it's there because the cells there have adapted out, there's no change. So your nervous system is largely responding to change. This is also why when you walk into a room and you often notice a novel smell, let's hope it's a good smell, after a few minutes or so, you don't notice the smell anymore because your olfactory system adapted that away. So a lot of that adaptation is prevented by those little micro saccades and the macro saccades, the bigger saccades are really for moving your eyes around to look for things in visual space. Smooth pursuit is a very particular kind of visual behavior that you can do in a smooth pursuit task. Again, zero cost costs a little bit of time, I suppose, to do this on YouTube. And most any of them will do. We can provide a link in the show note captions of one that we like or several that we like. But by doing that smooth pursuit task for a bit each day, maybe just a minute or two, you're maintaining your ability through the musculature of the eye to do smooth pursuit. And of course, you do smooth pursuit when you move about your day. But for people that are trying to offset or reverse vision loss, doing some additional deliberate smooth pursuit exercises can be useful. The other visual exercise that can be very useful is the so-called near far exercise. So this is best accomplished, I think, by holding out a pen or pencil in front of your eyes, in front of your head, and focusing very intensely through what's called a virgins eye movement, where you bring both eyes to the tip of the pen, and then moving that pen closer and closer and closer to your eyes where you get close enough that you actually have to deliberately bring your eyes. For those of you listening, this is what I'm doing right now. To the point where it's blurry and you can no longer hold it in sharp, crisp relief. You can't see it sharply, that is. And then you can move it out a little bit distance and kind of play right around that threshold where it's hard to keep it in focus now. And then move it back out again and then in doing that for even a minute or two, you'll find is a bit of a strain on your eyes, but you can actually build up the musculature and the neuromuscular connections that allow you to do that more efficiently. And that has been shown to improve certain aspects of vision, especially when people are diligent about doing those exercises, not necessarily every day, but let's say three days a week or so. They can be very fast. I actually find them kind of fun for reasons that escape me entirely. Now, how close you can bring that object and still maintain it in sharp focus will vary from person to person based on a number of things. First of all, how healthy and well-performing their neural retina is, whether or not they have myopia or hyperopia, nearsightedness, et cetera. Whether or not, for instance, you're like me and you have a fairly close interpupillary distance or whether or not you're more wall-eyed and you have your eyes set further apart. All those things will dictate the exact performance of that task, but nonetheless, it's a very useful task to do when trying to maintain or improve vision. Now, of course, there are a lot more behavioral tools that one could use to maintain or enhance vision. I'm really touching on the biggest and what I consider the most important ones that are most accessible to people without the need for any fancy equipment at all. And if you want to learn more about other behavioral tools that one can use to maintain or enhance vision, please see the episode that we did on eyesight. You can simply go to hubermanlab.com, put into the search function, eyesight or vision, and it'll take you right to it. In fact, everything on that website is keyword indexed and will take you to the various episodes and timestamps that you're interested in according to that keyword. Now, the person who asked this question, who by the way is Paige Singer. Thank you, Paige Singer. And the question got a lot of upvotes because apparently there's a lot of interest in this, understandably so. Asked about nutrition and supplements for maintaining or improving vision. That could be a very lengthy conversation, but let's just summarize it with a few brief points that we know stand based on the clinical and scientific research. We've all heard that carrots are good for your eyes. Well, it's not carrots per se that are good for your eyes. It's vitamin A that's essential for the so-called phototransduction cascade. The phototransduction cascade is the process by which the photoreceptors, which are in the back of the retina, at least if you're a human, they're in the back of the retina, take photons, light energy and convert it into electrical signals that's then conveyed to the other cells and neurons within the retina and then passed into the brain to create visual percepts. Most people can get enough of this fat soluble vitamin, we call vitamin A, by making sure that they eat at least some dark green leafy vegetables and that they do that in their closest to raw form, maybe cooked a little bit, but not overly cooked. There are other sources of vitamin A out there. You can look those up online just for sources of vitamin A. Most people will be able to get enough vitamin A from their nutrition and won't require it from a supplement, provided that it's not present at excessively high levels in a foundational supplement or vitamin mineral supplement. Getting in some additional vitamin A from a foundational supplement or vitamin mineral supplement, it's probably not going to be an issue unless you really take in far too much of that vitamin A and could potentially provide some insurance. But again, I think most people can get enough vitamin A from their diet if they are taking care to eat the foods that contain vitamin A. Green leafy vegetables being one. The other food that's known to be highly enriched in vitamin A is liver. One of my least favorite foods, regardless of what animal that liver comes from. Liver is somewhat of a popular slash controversial organ meat in the nutrition space for reasons that aren't interesting for sake of this discussion anyway. I suppose for those of you that like liver, you could eat a little bit of liver every once in a while. It is rich in a number of things that are beneficial to health. Although for you vegans out there, I'm sure you'll want to avoid liver entirely. I avoid liver because I just simply don't like the way it tastes. Maybe once or twice I've tasted liver that was appetizing to me. And it can be okay, but it's just not, or at least by my read, it can be okay. But it's not a food that I actively seek out, order or prepare for myself on a regular basis. So fortunately there are other sources of vitamin A as well. And again, I just invite you to all put into a web search, food sources of vitamin A and figure out how to get your daily dose of vitamin A by taking in foods that you like for you. And then in terms of supplementation of things that can enhance vision, this is a newer area. And frankly, it's an area where most of the data point to some supplements that can potentially be beneficial in certain disease conditions. So for instance, in fairly progressed age-related macular degeneration, age-related macular degeneration is fairly common or more common than we would like, we should say. And it does appear that supplementing with certain things like lutein, which is present in eggs or egg yolks in particular, especially egg yolks that aren't overly cooked or that can be supplemented can potentially help with some instances of age-related macular degeneration. But the data on this are still emerging. I consulted with our chair of ophthalmology at Stanford about lutein and some of the other things that you'll see out there, like zeaxanthine and astaxanthines. And these xanthines come from certain fruits like blueberries and they're present in supplements and things of that sort. The consensus I got talking to him and talking to some other ophthalmologists are that if you're really aiming to get a healthy diet, you're avoiding cigarette smoking. And by healthy diet, I mean getting sufficient amounts of vitamin A and lutein through food sources. Again, you can look up where those food sources are. Egg yolks just being one of them. Well, then chances are you're not going to need to supplement with lutein or the xanthines or the astaxanthines. However, I have heard anecdotal reports from a number of people that they'll start taking a supplement for eye health. There are a number of them out there. We are not as a podcast affiliate with any of those eye health supplements, by the way. And people are reporting enhanced vision.