The Science of Vision, Eye Health & Seeing Better

**Andrew D. 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. This podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero cost to consumer information about science and science-related tools to the general public. In keeping with that theme, I'd like to thank the sponsors of today's podcast. Our first sponsor is Athletic Greens. Athletic Greens is an all-in-one vitamin mineral probiotic drink. I've been taking Athletic Greens since 2012, so I'm delighted that they're sponsoring the podcast. The reason I started taking Athletic Greens and the reason I still take Athletic Greens once or twice a day is that it helps me cover all of my basic nutritional needs. It makes up for any deficiencies that I might have. In addition, it has probiotics, which are vital for microbiome health. I've done a couple of episodes now on the so-called gut microbiome and the ways in which the microbiome interacts with your immune system, with your brain to regulate mood, and essentially with every biological system relevant to health throughout your brain and body. With Athletic Greens, I get the vitamins I need, the minerals I need and the probiotics to support my microbiome. If you'd like to try Athletic Greens, you can go to athleticgreens.com/huberman and claim a special offer. They'll give you five free travel packs plus a year supply of vitamin D3 K2. There are a ton of data now showing that vitamin D3 is essential for various aspects of our brain and body health. Even if we're getting a lot of sunshine, many of us are still deficient in vitamin D3. And K2 is also important because it regulates things like cardiovascular function, calcium in the body and so on. Again, go to athleticgreens.com/huberman to claim the special offer of the five free travel packs and the year supply of vitamin D3 K2. Today's episode is also brought to us by Element. Element is an electrolyte drink that has everything you need and nothing you don't. That means the exact ratios of electrolytes are an element and those are sodium, magnesium and potassium, but it has no sugar. I've talked many times before on this podcast about the key role of hydration and electrolytes for nerve cell function, neuron function, as well as the function of all the cells and all the tissues and organ systems of the body. If we have sodium, magnesium and potassium present in the proper ratios, all of those cells function properly and all our bodily systems can be optimized. If the electrolytes are not present and if hydration is low, we simply can't think as well as we would otherwise. Our mood is off, hormone systems go off, our ability to get into physical action, to engage in endurance and strength and all sorts of other things is diminished. So with element, you can make sure that you're staying on top of your hydration and that you're getting the proper ratios of electrolytes. If you'd like to try element, you can go to drink element, that's lmnt.com/huberman, and you'll get a free element sample pack with your purchase. They're all delicious. So again, if you want to try element, you can go to element, lmnt.com/huberman.
Today's episode is also brought to us by Thesis. Thesis makes what are called nootropics, which means smart drugs. Now, to be honest, I am not a fan of the term nootropics. I don't believe in smart drugs in the sense that I don't believe that there's any one substance or collection of substances that can make us smarter. I do believe based on science, however, that there are particular neural circuits and brain functions that allow us to be more focused, more alert, access creativity, be more motivated, et cetera. That's just the way that the brain works, different neural circuits for different brain states. Thesis understands this. And as far as I know, they're the first nootropics company to create targeted nootropics for specific outcomes. I've been using Thesis for more than six months now, and I can confidently say that the nootropics have been a total game changer. My go-to formula is the Clarity formula, or sometimes I'll use their Energy formula before training. To get your own personalized nootropic starter kit, go online to takethesis.com/huberman.
Take a three-minute quiz, and Thesis will send you four different formulas to try in your first month. That's takethesis.com/huberman, and use the code Huberman at checkout for 10% off your first order. We are now beginning a new topic for the next four to five episodes of the Huberman Lab podcast. Before we move into that, I want to just briefly touch on a couple of questions that I got from the last episode, which was related to the science of endurance training. I described the four kinds of endurance training. We posted protocols of the specific four kinds of endurance training at hubermanlab.com. Just go to that episode. You can see the download. It's a zero cost PDF. I got a lot of questions about what's called concurrent training, which is how to program endurance training if you are also interested in strength and hypertrophy training, or how to incorporate strength and hypertrophy training, which was in the previous episode, with endurance training. This can all be made very simple. Ask yourself, what are you trying to emphasize? And then emphasize that for a 10 to 12 week cycle. So if you're mostly interested in endurance, I would say use a three to two ratio. Maybe get three endurance training workouts per week, maybe four, and two strength and hypertrophy workouts. If you're mainly focusing on strength and hypertrophy, get three or four workouts for strength and hypertrophy and do two endurance workouts. Start with the minimum number of sets that's required to get the result that you want. So if you're not accustomed to doing endurance work, you would start with the minimum number that's listed on that protocol. So if it says three to five sets, you would start with three, maybe even just two, and then work your way up by adding sets each week. I do suggest that people get at least one complete rest day per week, although I know a lot of people don't like that. I benefit from that. I actually benefit from having two complete rest days each week. I just continue to make progress that way, whether or not it's for strength and hypertrophy or for endurance. I am a big believer in rest days. Other people are not. And those could be active rest days, hiking, relaxing, et cetera. After a 10 to 12 week cycle, then I also suggest taking anywhere from five to seven days completely off. You can still enjoy life and do things. I know for you addicted exercisers that you're going to loathe to do that, but that's one way to stay injury free, keep your joints and tissues healthy over time and continue to make progress. If you don't want to do that week off, don't do it. None of this is holy. None of it is a strict prescriptive. Just ask yourself, what are you going to emphasize? And emphasize that in terms of the total volume of workouts that you do and work up incrementally and then move into another cycle. That's what I suggest. So go to hubermanlab.com. You can get the protocol there. We are now going to move into a new topic unrelated to physical performance, starting with this episode. And for the next four to five episodes, we are going to talk all about the senses. That's sight, eyesight, hearing, touch, taste, smell. And we are also going to talk about this critical sense that we call interoception or our sense of our internal real estate. Now, the reason that we are talking about the senses is because if you understand how the senses are perceived, what they're about, what the underlying cells and connections are about, you will be in a terrific position to understand the month's topic that follows, which is all about mental health. Now, I want to emphasize that if you're somebody who doesn't have any trouble seeing, hearing, tasting, smelling, and has an excellent sense of interoception, I do believe that these episodes will still be very relevant to you because they have everything to do with how you move through the world, how you make sense of information, and how you organize your thoughts and your emotions. I also want to emphasize that we're going to cover a lot of practical tools. So today's episode is going to be all about vision and eyesight, a topic that's very near and dear to my heart because it's the one that I've been focusing on for well over 25 years of my career. But we're not just going to get into the mechanistic details about how light is converted into electrical potentials and things like that. We are going to talk about practical tools that you can and should use to help maintain the health of your visual system and your eyesight. Very often young people will say, what should I do? You're always talking about neuroplasticity and how it tapers off over time, but I'm a young person, what should I do? You should absolutely train and support your eyesight. In fact, if you're a young person and you see perfectly, or you feel as if you see the world perfectly, you are in the best position to bolster, to reinforce that visual system so that you don't lose your vision as you age. In addition, you can leverage your visual system for better mental and physical performance. And we're going to talk about that. If you're somebody who suffers from a clinical disorder of vision, you have trouble seeing, or if you need corrective lenses in order to see, this episode is definitely for you. And while, of course, I can't make clinical diagnoses, I can't have a one-to-one conversation with any of you in this format, nor am I a clinician, I'm a scientist, not a physician. I did consult with our chair of ophthalmology, Dr. Jeffrey Goldberg at Stanford University School of Medicine, as well as several other people to really vet the information and make sure that the protocols that I'm describing are consistent with the clinical literature. If you have a severe eye problem, you should be working with a really good ophthalmologist and or optometrist, but certainly an ophthalmologist who's a medical doctor. But I do believe that the information that we're going to discuss today is going to be relevant to everybody and we'll set the stage for the month on mental health and mental performance. So let's get started. When we hear the word vision, we most often think about eyesight or our ability to perceive shapes and objects and faces and colors. And indeed, vision involves eyesight, our ability to see shapes and objects and faces and colors and so forth. However, our eyes are responsible for much more than that, including our mood, our level of alertness, and all of that is included in what we call vision. So I just want to take about three, maybe four minutes and talk about how the visual system works, how it's built and how you are able to so-called see things around you. I also want to describe the ways in which your eyes and your visual system impact your mood and your level of alertness. And then we are going to get right into some protocols, some specific things that each and all of you should do if you want to enhance your vision and maintain your vision as you get older. And again, if you're a 15 year old or a 12 year old, this episode is especially for you because your nervous system is far more plastic than mine is. It's much more amenable to change. So you can really build a very strong visual system. And in doing that, and if you adopt specific behaviors at any age of light viewing at particular times in particular ways, then you can build an emotional system that's also reinforced by your visual system. So let's talk about vision. What is vision? Well, vision starts with the eyes. We have no what's called extraocular light perception. While it feels good to have light on our skin, while it feels good to be outside in the sunlight for most people, the only way that light information can get to the cells of your body is through these two little goodies on the front of your face. And for those of you listening, I'm just pointing to my eyes. As many of you have heard me say before on this and other podcasts, your eyes in particular, your neural retinas are part of your central nervous system. They are part of your brain. They're the only part of your brain that sits outside the cranial vault. In other words, you have two pieces of your brain that deliberately got squeezed out of the skull during development and placed in these things we call eye sockets. There's a genetic program for the specific purpose of making sure that three little layers of neurons, nerve cells got squeezed out and form what are called your neural retinas. Now, the eyes have a lot of other goodies in them that are very important. And those are the goodies that we're going to focus on a lot today. There's a lens to focus light precisely to the retina. If you're somebody who requires eyeglasses or contacts, chances are you don't do that correctly. And so that's why you use other lenses like eyeglasses or contacts. There are also other pieces of the eye that are designed to keep the eye lubricated. You also have these things that we call eyelashes. Most people don't know this, but eyelashes are there to trigger the blink reflex if a piece of dust or something gets in front of your eye. It's a beautiful adaptation of nature. They aren't just aesthetically nice. Costello happens to have very long eyelashes. He gets compliments about this all the time. Maybe you have long eyelashes. I don't have particularly long eyelashes, but the eyelashes are there so that if a piece of dust or something starts to head towards the cornea, the eye blinks very, very fast. It's the fastest reflex you own is your eye blink reflex. We also have these things called eyelids. Now, eyelids might seem like the most boring topic of all, but they are incredibly fascinating. Today, we're going to talk about how you can actually use your visual system to increase your levels of alertness based on the neural circuits that link your brainstem with your eyelids. And no, we are not going to have a blinking contest because I would win and you would lose. And that wouldn't be fun for you. So, let's talk about what the eyes do for vision. Basically, the entire job of the eyes is to collect light information and send it off to the rest of the brain in a form that the brain can understand. Remember, no light actually gets in past those neural retinas. It gets to the neural retina and we have specific cells in the eye called photoreceptors. They come in two different types, rods and cones. Cones are mainly responsible for daytime vision and the rods are mainly responsible for vision at night or under low light conditions, generally speaking. So basically, what happens is if your eyelids are open, light comes into the eye, the lens focuses that light, light is also just called photons, light energy, onto the retina. These photoreceptors, the rods and cones, have chemical reactions inside them that involve things like vitamin A and that chemical reaction converts the light into electricity. Now, that might seem incredibly abstract, but the way to think about this is very similar to, for instance, you have touch receptors on your skin and when you press on those touch receptors, they convert pressure, physical pressure, into electrical information and those neurons send it up to your spinal cord and brain and you can register that somebody or you are touching the top of your hand as I'm doing now. With the eyes and the retina, it's just that light gets converted into electrical information. Within the eye, within the retina, there are then a series of stages of processing and that information eventually gets sent into the brain by a very specific class of neurons. I would like you to know the names of these neurons. They're called retinal ganglion cells. So the only thing you need to know about the neuroscience of the eye at this point are that they're rods and cones. The cones are involved in bright daytime vision and rods are involved in more dusk or nighttime vision. And you've got these cells called retinal ganglion cells that send the information off to the rest of the brain. Now, here's what's incredible. I just want you to ponder this for a second. This still blows my mind.