Using Light (Sunlight, Blue Light & Red Light) to Optimize Health

This section of the episode develops the topic through the following source points: 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 we are going to discuss light and the many powerful uses of light to optimize our health. We're going to discuss the use of light for optimizing skin health, appearance and longevity, for wound healing, for optimizing hormone balance, and for regulating sleep, alertness, mood, and even for offsetting dementia. One of the reasons why light has such powerful effects on so many different aspects of our biology is that it can be translated into electrical signals in our brain and body, into hormone signals in our brain and body, and, indeed, into what we call cascades of biological pathways, meaning light can actually change the genes that the cells of your body express, and that is true throughout the lifespan. Today, I will discuss the mechanisms by which all of that occurs. I promise to make it clear for those of you that don't have a biology background, and if you do have a biology background, I'll try and provide sufficient depth so that it's still of interest to you. And I promise to give you tools, very specific protocols that are extracted from the peer-review literature that will allow you to use different so-called wavelengths, which most of us think of as colors, of light in order to modulate your health in the ways that are most important to you. For those of you that are thinking that the use of light to modulate health falls under the category of woo science, pseudoscience or biohacking, well, nothing could be further from the truth. In fact, in 1903, the Nobel Prize was given to Niels Finsen. He was Icelandic; he lived in Denmark for the use of phototherapy for the treatment of lupus. So there's more than a hundred years of quality science emphasizing the use of light, and as you'll soon see, the use of particular wavelengths, or colors of light, in order to modulate the activity of cells in the brain and body. So while it is the case that many places and companies are selling therapies and products related to the use of flashing lights and colored lights, promising specific outcomes from everything from stem cell renewal to improvement of brain function, and some of those don't have any basis in science, there are phototherapies that do have a strong foundation in quality science, and those are the studies and the protocols that we are going to discuss today.

This section of the episode develops the topic through the following source points: If it didn't sound weird enough that you can pass light through particular tissues and have them land and be absorbed at tissues deeper in your body, well, it turns out that different wavelengths of light are also best absorbed by particular so-called organelles within your cells. What are organelles? Organelles are the different compartments and different functions within a given cell. So for instance, your mitochondria, which are responsible for generating ATP and energy in your cells, those exist at a particular depth, at a particular location within a cell. They're not all at the cell surface. They sit somewhat deeper in the cell. The nucleus of your individual cells contains DNA and that sits at a particular depth or location within your cell. Different wavelengths of light not only can penetrate down into different tissues and into different cells of your body, but they can also penetrate and access particular organelles, meaning mitochondria or the nucleus or the different aspects of your cells that are responsible for different functions. This is exquisitely important and it's exquisitely powerful because as you'll learn today, particular wavelengths of light can be used to stimulate the function of particular organelles within particular cells, within particular organs of your body. I can think of no other form of energy, not sound, not chemical energy, so not drugs, not food, not touch, no form of energy that can target the particular locations in our cells, in our organelles, in our organs, and in our body to the extent that light can. In other words, if you had to imagine a real world surgical tool by which to modulate our biology light would be the sharpest and the most precise of those tools. Now, let's talk about how light is converted into biological signals, several ways in which that is accomplished. But the fundamental thing to understand is this notion of absorption of light energy, certain pigments or colors in the thing that is receiving the light energy, meaning the thing that the light energy lands on are going to absorb particular wavelengths of light. Now, I promise you that you already intuitively know how this works. For instance, if you were to sit outside on a very bright sunny day and you had a table in front of you that was metal, you might find it hard to look down at that metal table because it's reflecting a lot of light of particular wavelengths. If that table were pitch black, however, it wouldn't reflect quite as much and you would be able to comfortably look at it. If that table were red, it might be somewhere in between. If that table were green, it would be also somewhere in between. But let's say it were very light blue, well then it might reflect almost as much as a table that were just metal or a white table surface. So the absorbance properties of a given surface will determine whether or not light energy goes and stays at that location and has an impact on that location, or whether not it bounces off. Every biological function of light has to do with the absorbance or the reflectance of light or light passing through that particular thing, meaning that particular cell or compartment within a cell. I'd like to make it clear how this works by using the three primary examples of how you take light in your environment and convert it into biological events. We have photoreceptors in the back of our eyes. These photoreceptors come in two major types, the so-called rods and the cones. The rods are very elongated. They look like rods and the cones look like little triangles. Rods and cones have within them photopigment. They have dark stuff that's stacked up in little layers. Rods absorb light of essentially any wavelength. There's some variation to that, but let's just say rods don't care about the different colors of light. They will absorb light energy, photon energy; if it's red, if it's green, if it's blue, if it's yellow, doesn't matter, as long as that light is bright enough. It turns out that rods are very, very sensitive. They can detect very, very small numbers of photons. And rods are essentially what you use to see in very low light conditions. We'll return more to vision later.