Huberman Lab
Journal Club with Dr. Peter Attia | Effects of Light & Dark on Mental Health & Treatments for Cancer
22 Jan 2024
Chapter 1: What is the significance of light and dark exposure on mental health?
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 marks the second episode in our Journal Club series with myself and Dr. Peter Attia. Dr. Peter Attia, as many of you know, is a medical doctor.
who is a world expert in all things healthspan and lifespan. He is the author of the bestselling book, Outlive, as well as the host of his own terrific podcast, The Drive. For today's episode, Peter and I each select a different paper to share with you. We selected these papers because we feel they are both extremely interesting and extremely actionable.
First, I present a paper that is about how light exposure during the morning and daytime, as well as dark exposure at night, each have independent and positive effects on mental health, as well as the ability to reduce the symptoms of many different mental health disorders.
Now I've talked before on this podcast and elsewhere about the key importance of seeing morning sunlight, as well as trying to be in dim light at night.
Chapter 2: How does outdoor light compare to indoor light in terms of health benefits?
However, the data presented in the paper today really expands on that by identifying the key importance of not just morning sunlight, but getting bright light in one's eyes as much as is safely possible throughout the entire day and a separate additive effect, of being in as much darkness at night as possible.
I describe the data in a lot of detail, although you do not need a background in biology in order to understand that discussion. And there's a key takeaway, which is that if you can't get enough light in your eyes during the daytime, you would be well advised to get as much darkness exposure at night. In other words, light and dark have independent and additive effects on mental health.
And during today's discussion, you'll learn exactly how to apply light exposure and dark exposure in order to get those benefits. Then Peter presents a paper about novel treatments for cancer. I must say it's an extremely important conversation that everybody, regardless of whether or not you may have had cancer or know somebody who's had cancer, ought to listen to.
He highlights the current technology of cancer treatments as well as the future technology of cancer treatments and the key role that the immune system and the autoimmune system play in treatments for cancer.
I assure you that by the end of today's Journal Club episode, you will have learned a ton of new information about light and dark and mental health, as well as cancer and the immune system and treatments for curing cancer. Before we begin, I'd like to emphasize that 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.
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Chapter 3: What are practical tools for optimizing light exposure?
In keeping with that theme, I'd like to thank the sponsors of today's podcast. Today's episode is also brought to us by Waking Up. Waking Up is a meditation app that includes hundreds of meditation programs, mindfulness trainings, yoga nidra sessions, and NSDR, non-sleep-depressed protocols.
I started using the Waking Up app a few years ago because even though I've been doing regular meditation since my teens, and I started doing yoga nidra about a decade ago.
My dad mentioned to me that he had found an app, turned out to be the Waking Up app, which could teach you meditations of different durations and that had a lot of different types of meditations to place the brain and body into different states and that he liked it very much.
I gave the waking up app a try and I too found it to be extremely useful because sometimes I only have a few minutes to meditate.
Chapter 4: How do light and dark exposure independently affect mental health?
Other times I have longer to meditate. And indeed, I love the fact that I can explore different types of meditation to bring about different levels of understanding about consciousness, but also to place my brain and body into lots of different kinds of states, depending on which meditation I do. I also love that the Waking Up app has lots of different types of yoga nidra sessions.
For those of you who don't know, yoga nidra is a process of lying very still, but keeping an active mind. It's very different than most meditations. And there's excellent scientific data to show that yoga nidra and something similar to it called non-sleep deep rest or NSDR can greatly restore levels of cognitive and physical energy, even with just a short 10 minute session.
If you'd like to try the Waking Up app, you can go to wakingup.com slash Huberman and access a free 30-day trial. Again, that's wakingup.com slash Huberman to access a free 30-day trial. And now for my discussion with Dr. Peter Attia.
Andrew, great to have you here for Journal Club number two. I'm already confident this is going to become a regular for us.
I'm excited. I really enjoy this because I get to pick papers I'm really excited about. I get to hear papers that you're excited about and we get to sharpen our skills at reading and sharing data and people listening can do that as well.
So last time I went first, so I think I'm going to put you in the hot seat first and have you go first and I'll follow you.
Okay. Well, I'm really excited about this paper for a number of reasons. First of all, it, at least by my read, is a very powerful paper in the sense that it examined light exposure behavior as well as dark exposure behavior. And that's going to be an important point in more than 85,000 people as part of this cohort in the UK.
I'll just mention a couple of things to give people background, and I'll keep this relatively brief. First of all, there's a long-standing interest in the relationship between light and mental health and physical health. And we can throw up some very... Well agreed upon bullet points. First of all, there is such a thing as seasonal affective disorder.
It doesn't just impact people living at really Northern locations, but basically there's a correlation between day length and mood and mental health such that for many people, not all, but for many people, when days are longer in the spring and summer, they feel better. They report fewer depressive symptoms.
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Chapter 5: How do T cells recognize and respond to cancer?
Now, let's first of all talk about how it works. And then when I tell you how it works, you'll say, that sounds amazing. Clearly, it should be able to destroy cancer. I'm going to simplify it by only talking about one system, which is how T cells recognize and get activated, how T cells recognize antigens. So we have something called an antigen. So an antigen is an antibody generating peptide.
So it's a protein, almost always a protein. They can be carbohydrates. But they're almost always proteins and they're very, very small peptides. Like we're talking as little as nine amino acids, maybe up to 20 amino acids. So teeny tiny little peptides. But it's amazing that in such a short peptide, the body can recognize if that's Andrew or not Andrew.
Chapter 6: What are the key differences between MHC class 1 and MHC class 2?
mean when again think about like we talk about proteins in kilodaltons right we're talking about proteins in terms of thousands of amino acids that make up every protein in your body and yet if it samples a protein and sees that hey this little 9 10 15 peptide amino acid is not part of you i know it's bad and therefore i'm going to generate an immune response to it
So we have what are called antigen-presenting cells. You have cells that go around sampling peptides, and they will, on these things called MHC class receptors, bring the peptide up to the surface and serve it up to the T cell. There are two types of these. There's MHC class 1 and MHC class 2.
So this is major histocompatibility complex.
That's correct. And we refer to them that way because of the context in which they were discovered, which was for organ rejection. So not surprisingly, when you need to put a kidney into another person, if that kidney is deemed foreign, it will not last long. And the early days of organ transplantation were rife with immediate rejections.
I mean, the immediates are the ABO incompatibilities, but the sort of next layer of incompatibility was MHC incompatibility, which would lead to within weeks the organ is gone as opposed to within hours. You have these two classes of MHC. You have class one and class two. Class one is what we call endogenous.
So this is basically what happens when a protein or an antigen is coming from inside the cell. So let's consider the flu. So if you get the flu, the influenza virus infects the respiratory epithelium of your larynx. And that virus, as folks listening might remember from our days of talking about COVID, viruses can't replicate on their own.
What they do is they hijack the replication machinery of the host, and they use that either to insert their RNA or DNA to replicate. And in the process, proteins are being made. Well, those proteins are the proteins of the virus, not of us. So some of those peptides get launched onto these MHC class one gloves. Basically, the glove comes up to the surface and a T cell comes along.
And in the case of MHC class one, it's a CD8 T cell. These are what are called the killer T cells, right? And so this cell comes along and with its T cell receptor, the T cell receptor meets the MHC class one receptor with the antigen in it. And if that's a lock, it realizes that's my target.
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Chapter 7: What are the challenges and advancements in cancer treatment?
And it begins to replicate and proliferate and target those. And that creates the immune response. And by the way, that's how it works when you vaccinate somebody. You're basically pre-building that thing up.
So would this fall under the adaptive immune response or the innate immune response?
This is adaptive. Yep. Innate is just the pure antibody response on the B-cell side. I won't get into that for the purpose of this discussion. The other example is MHC class 2, and that's also part of the adaptive system or the innate system, which is more what we call the exogenous form. So these are peptides that are usually coming from outside the cell.
So we're going to focus more on the MHC class one because this is peptides that come from inside the cell. Okay. So just keep in the back of your mind, if a foreign protein gets presented from inside a cell to outside a cell, the T cells recognize that and they will mount a foreign response. And by the way, that's why we basically can beat any virus.
Like if you consider how many viruses are around us, the fact that we almost never die from a viral infection is a remarkable achievement. of how well this immune system works.
We're constantly combating these viruses.
Constantly. And by the way, we don't really have very effective antiviral agents. It's not like antibiotics. Like, we have antibiotics up the wazoo. I mean, we're way better at fighting viruses than bacteria.
Can I just ask one question? I've always wondered about this. To what extent is our ability to ward off viruses on a day-to-day basis as an adult reliant on us having been exposed to that virus during development? Like, as I walk around today, maybe I'll be exposed to 100,000 different viruses.
Would you say that half of those I've already got antibodies to because I was exposed to them at some prior portion of my life? Yeah, hard to quantify.
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Chapter 8: How does the immune system impact cancer survival rates?
And the other ones, I'm just building up antibodies. Like, I was on a plane last night. Someone was coughing, so I was hiding. And I had COVID a little while ago, so I wasn't too worried about that. And I feel great today. But, you know... I just assume that on that plane, I'm in a swamp of viruses no matter what, and that most of them I've already been exposed to since I was a little kid.
So I've got all the antibodies and they're just fighting it back, binding up those viruses and destroying them.
Yeah, I think it's part that, and I also think it's part of them that our body can destroy without mounting much of an immune response. Your immune system is doing the work, and yet it's not mounting a systemic inflammatory response that you're not sensing.
So is it also a physical trapping in my nasal epithelium? It's a virus.
Yeah. So yeah. You have huge barriers, right? So the skin, the hairs in your nose, all of these things are huge barriers. But assuming that still a bunch of them are getting in, at least the respiratory ones, that's the other thing to keep in mind, right? There are certain viruses that are totally useless floating around the air, right?
There are certain viruses, you know, the viruses that most people are really afraid of, you know, Hep C, Hep B, HIV. Well, you know, if they're sitting on a table or floating around the air, they're of no threat to you. They have to be, you know, sort of transmitted through the barrier. But again, some of these viruses you're going to defeat without an enormous response.
And then some of them, you know, why is influenza, quote unquote, such a bad virus? whereas the common respiratory cold kind of sidelines you for a day. It's the immune response that you're feeling. The bigger the immune response to the virus, the more you're feeling that. You feel your immune system going crazy, right? You know, the interleukins that are spiking,
The third spacing that occurs to get more and more of the immune cells there. The spike of your temperature as your body basically tries to cook the virus. All of that stuff is your body... The fatigue. Yeah. Yeah. You're being drained and all this happening. So... One more point I'll mention just to close the loop on the autoimmunity. How is it that we learn not to attack ourselves?
That's something called thymic selection that occurs in infancy. So you and I have a no good for nothing, tiny little thymus that would be, it's almost impossible to see these things. You know, when we used to operate on people, you know, the thymus is barely visible in an adult, in a healthy adult outside of thymic tumors. But in a child, the thymus is quite large.
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