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Prompts Used

Prompt 1: Context Setup

You are an expert data extractor tasked with analyzing a podcast transcript. 
I will provide you with part 1 of 1 from a podcast transcript. 
I will then ask you to extract different types of information from this content in subsequent messages. Please confirm you have received and understood the transcript content.

Transcript section:
[00:00:10.480 --> 00:00:16.000] Hey everyone, welcome to a sneak peek, Ask Me Anything, or AMA episode of the Drive podcast.
[00:00:16.000 --> 00:00:17.760] I'm your host, Peter Attia.
[00:00:17.760 --> 00:00:25.360] At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created.
[00:00:25.360 --> 00:00:30.880] Or you can learn more now by going to peteratiamd.com forward slash subscribe.
[00:00:30.880 --> 00:00:36.080] So without further delay, here's today's sneak peek of the Ask Me Anything episode.
[00:00:39.280 --> 00:00:42.240] Welcome to Ask Me Anything, episode 65.
[00:00:42.240 --> 00:00:45.200] I'm once again joined by my co-host, Nick Stenson.
[00:00:45.200 --> 00:00:47.760] In today's episode, we cover red light therapy.
[00:00:47.760 --> 00:00:50.560] It's a topic we get asked about all the time.
[00:00:50.560 --> 00:00:53.280] In fact, my wife asks me about it all the time.
[00:00:53.280 --> 00:00:56.240] So it was clear that it was time for an AMA.
[00:00:56.240 --> 00:01:02.160] In this conversation, we lay the foundation for what red light therapy is and why there is such an emphasis on it.
[00:01:02.160 --> 00:01:07.760] We then break down the various forms of red light therapy and their various treatments into whether or not I think they are beneficial.
[00:01:07.760 --> 00:01:12.320] In other words, we go through each application and review the data for them.
[00:01:12.320 --> 00:01:30.000] So these include red light therapy for aging in general, skin health and acne, wound healing, hair loss, eye health, exercise performance and recovery, metabolic health, general weight loss, spot fat loss, inflammation, injury rehab, and menstrual cramps for women.
[00:01:30.000 --> 00:01:36.080] So in other words, we go through each of these and do a detailed analysis of the literature.
[00:01:36.080 --> 00:01:46.800] We close this conversation by summarizing my overall takeaways for each use case and explain via a summary table that we created that breaks down everything you might want to know to understand this.
[00:01:46.800 --> 00:01:52.480] If you're a subscriber and you want to watch the full video of this podcast, you can find it on the show notes page.
[00:01:52.480 --> 00:01:57.840] If you're not a subscriber, you can watch a sneak peek of the video on our YouTube page.
[00:01:57.840 --> 00:02:01.960] So, without further delay, I hope you enjoy AMA number 65.
[00:02:07.000 --> 00:02:09.080] Peter, welcome to another AMA.
[00:02:09.080 --> 00:02:09.800] How are you doing?
[00:02:09.800 --> 00:02:10.040] Good.
[00:02:10.040 --> 00:02:11.560] Thanks for having me back.
[00:02:11.560 --> 00:02:12.360] Anytime.
[00:02:12.360 --> 00:02:13.320] Anytime.
[00:02:13.320 --> 00:02:18.680] So, today's AMA, we are going to focus on a single topic, which is red light therapy.
[00:02:18.680 --> 00:02:25.080] This is something we get asked about a lot, not only questions from the website and subscribers, but I know through your patients as well.
[00:02:25.080 --> 00:02:37.960] And so, we compiled all these questions and through this conversation, hopefully, going to cover what red light therapy is, how it can work, deep dive into some various claims out there around red light therapy.
[00:02:37.960 --> 00:02:50.280] This can include potential effect on skin health, wound healing, hair loss, eyesight, exercise performance, and recovery, metabolic health, fat loss, inflammation, chronic pain, and a lot more.
[00:02:50.280 --> 00:02:55.400] So, with all that said, anything you want to add before we get rolling into it?
[00:02:55.400 --> 00:02:56.680] Two unrelated things.
[00:02:56.680 --> 00:03:01.240] I notice you have a little visitor for the podcast today hanging out with you there.
[00:03:01.240 --> 00:03:04.520] Hopefully, he's interested, and this is something he'll like.
[00:03:04.520 --> 00:03:10.280] And secondly, I would add that my wife is specifically asking me these questions.
[00:03:10.280 --> 00:03:15.080] So, she's very keen to buy a whole bunch of red light things.
[00:03:15.080 --> 00:03:23.800] And I asked her to just hold off until we did the research for this episode so that we could at least have a sense of if there's value there, where it is.
[00:03:23.800 --> 00:03:25.640] I don't know if she's a subscriber, though.
[00:03:25.640 --> 00:03:29.000] So, if she's not, this might be the one that she subscribes for.
[00:03:29.000 --> 00:03:38.520] I respect that when your wife asks you medical questions, you say, Let me send you a podcast episode instead of telling her the answer like everyone else.
[00:03:38.520 --> 00:03:44.040] So, it's good to know you practice what you preach, even through your direct family.
[00:03:44.040 --> 00:03:44.480] Okay.
[00:03:44.760 --> 00:03:45.520] First question.
[00:03:45.760 --> 00:03:52.000] I think it's going to be helpful to just explain when we say red light therapy, what does that even mean?
[00:03:52.000 --> 00:03:57.840] Yeah, you can't do this without at least having some understanding of the physics and the principles.
[00:03:57.840 --> 00:04:05.920] that define light and waves come up over and over and over again as you try to evaluate the plausibility of the claims that are made here.
[00:04:05.920 --> 00:04:13.680] So when we're sitting here looking out at the world, we're looking at light and there's visible colors of light.
[00:04:13.680 --> 00:04:15.120] Maybe I should take a step back.
[00:04:15.120 --> 00:04:19.920] Light exists as waves and they're very short waves to be clear.
[00:04:19.920 --> 00:04:22.400] So sound waves are really, really long.
[00:04:22.400 --> 00:04:24.640] Light waves are really, really short.
[00:04:24.640 --> 00:04:32.000] And then obviously waves can get much, much shorter and you can get into UV, which we've talked about in detail on a previous podcast.
[00:04:32.000 --> 00:04:34.080] And then even shorter than that would be X-rays.
[00:04:34.080 --> 00:04:35.920] And then even shorter than that are gamma rays.
[00:04:35.920 --> 00:04:39.840] So as wavelengths get shorter, the energy gets more powerful.
[00:04:39.840 --> 00:04:57.920] But if we just focus on light, visible light runs the gamut from about 380 nanometers, which would be purple-ish, and then all the way at the longest end, about twice that 780 nanometers, is where red light is.
[00:04:57.920 --> 00:05:06.960] So when people talk about red light therapy, they're mostly talking about light that is in that very narrow band.
[00:05:06.960 --> 00:05:11.760] So for example, again, a white light is giving you all mixed across that entire range.
[00:05:11.760 --> 00:05:14.320] Red light would be more narrowly focused.
[00:05:14.320 --> 00:05:19.400] It's also important to understand that, and we'll talk about this a little bit today.
[00:05:19.400 --> 00:05:30.520] Phototherapy in general involves wavelengths across that entire band of visible light, but it also includes something called near-infrared.
[00:05:31.160 --> 00:05:38.840] So that basically runs the gamut from about 400 to 1100 nanometers.
[00:05:38.840 --> 00:05:57.480] So I think the easiest way to think about this is red light therapy, which runs about 620 to 780 nanometers, and then near infrared, which is right adjacent to that, the next thing up in terms of length, which is about 790 to 1400.
[00:05:57.800 --> 00:06:10.280] So again, if you forget everything else, just remember when people talk about red light therapy, they're talking about wavelengths that are just in that red visible area of 620 to 780.
[00:06:10.280 --> 00:06:15.080] And then often they talk about near-infrared as well, which is not visible.
[00:06:15.080 --> 00:06:21.640] To be clear, you don't see it, but it's just a little bit longer, 790 to 1400 nanometers.
[00:06:21.640 --> 00:06:31.000] We'll come back to this over and over again because there are some instances where the fact that you can't see it might actually make it a little more dangerous.
[00:06:31.000 --> 00:06:44.040] Double-clicking on red light therapy, can we explain a little bit more about what is special about it and why there's so much emphasis on it, as talked about for the various claims that we'll speak about today?
[00:06:44.360 --> 00:06:58.040] People who listened to our podcast on ultraviolet light may recall a distinction I made between UVA and UVB, which came down to the degree of penetration.
[00:06:58.040 --> 00:07:19.760] And so similarly, when you think about red light therapy, and you remember that the longer a wavelength, the more it can penetrate, albeit with less energy, what makes red light interesting is it is sort of at this sweet spot where it has some capacity to penetrate more so than other forms of visible light.
[00:07:14.920 --> 00:07:22.000] That's sort of part of what makes this interesting.
[00:07:22.240 --> 00:07:32.080] Now, the exact depth that's reached by the red light or the near-infrared is kind of a function of how the light beams are organized.
[00:07:32.080 --> 00:07:38.240] So, what is the amount of coherence, which is how much do the wavelengths line up with each other?
[00:07:38.240 --> 00:07:44.640] So, if the wavelengths are all coherent, the peaks and valleys are in the same place, it's going to have more penetrance.
[00:07:44.640 --> 00:07:48.800] And then, what's the extent to which they're all aligned in the exact same direction?
[00:07:48.800 --> 00:07:50.560] That's called collimation.
[00:07:50.560 --> 00:07:55.840] So, in other words, the light isn't spreading, but rather it's all pointed in the exact same direction.
[00:07:55.840 --> 00:08:10.080] And then, finally, you have the intensity, and we'll talk a little bit about the difference between watts and joules, because if people are looking at these devices, sometimes they give you information in watts, and sometimes they give you information in joules, which of course, there's a very clear relationship between them.
[00:08:10.080 --> 00:08:13.360] And, of course, broadly speaking, energy matters as well.
[00:08:13.360 --> 00:08:28.640] So, when you take all of that into account, though, the really important principle that I think gets perhaps missed when people evaluate these things is that for the most part, red light can't penetrate nearly as much as people think it can.
[00:08:28.640 --> 00:08:29.120] Okay.
[00:08:29.120 --> 00:08:39.760] If red light is being delivered by LEDs, which is the most common way that it is, it's going to be able to penetrate about two to three millimeters into skin.
[00:08:39.760 --> 00:08:48.160] Now, infrared light can go a little bit deeper, because remember, it's a longer wavelength, and it can reach probably five to 10 millimeters.
[00:08:48.160 --> 00:08:57.840] Now, if red light is delivered by a laser, because again, you now have a more focused form of light energy, it could penetrate significantly higher than that.
[00:08:57.840 --> 00:09:00.000] It could go from one to four centimeters.
[00:09:00.440 --> 00:09:08.280] So, again, keep in mind the way that the light is organized plays a significant role in the depth that it can penetrate.
[00:09:08.280 --> 00:09:27.560] Now, if you start to think about some of the applications we're going to talk about, when you start to think about red light therapy, just keep in the back of your mind: if something can only penetrate one to three millimeters, it's going to be difficult for it to have some of the profound effects that are sometimes claimed.
[00:09:27.560 --> 00:09:36.360] Even if something can penetrate 10 millimeters or a centimeter, which would be quite deep, it's not clear that that's going to be able to have a significant effect.
[00:09:36.360 --> 00:09:45.240] And so, as a general rule of thumb, the more superficial the application, the more plausible I think it's going to be as we go through these.
[00:09:45.560 --> 00:09:58.120] Last foundational question before we get to the various claims and where this could be beneficial or not is, in general, what happens when the tissue is exposed to red light?
[00:09:58.120 --> 00:10:01.080] This is an important and, as you said, foundational question.
[00:10:01.400 --> 00:10:12.680] So, to have any biologic effect, the light needs to be absorbed by some photosensitive molecule within the cell or tissue that it's hitting.
[00:10:12.680 --> 00:10:23.880] And so, the absorption of light by these photosensitive molecules, which are called chromophores, cause a localized chemical change or a photochemical reaction.
[00:10:23.880 --> 00:10:32.600] Now, the most interesting of these is probably something called cytochrome C oxidase, or CCO.
[00:10:32.600 --> 00:10:37.320] It's a component of the electron transport chain within mitochondria.
[00:10:37.320 --> 00:10:55.280] And generally speaking, most people who are proponents of red light therapy point to cytochrome C oxidase or CCO as the main target and therefore the mediating effect of the biologic impact of red light.
[00:10:55.280 --> 00:11:06.320] So red light and near-infrared wavelengths do seem to excite cytochrome C oxidase, and its activity then increases subsequent ATP production.
[00:11:06.320 --> 00:11:19.200] Conversely, blue and green wavelengths, remember these are shorter, less penetrant, but more powerful, seem to decrease the activity of CCO and subsequently decrease ATP production.
[00:11:19.280 --> 00:11:32.800] Now, kind of getting into various claims of where red light therapy can be beneficial or not, I think it'd help to maybe start with what do we know about the idea that red light therapy can combat aging as a whole.
[00:11:33.120 --> 00:11:37.360] Thank you for listening to today's sneak peek AMA episode of The Drive.
[00:11:37.360 --> 00:11:43.040] If you're interested in hearing the complete version of this AMA, you'll want to become a premium member.
[00:11:43.040 --> 00:11:47.840] It's extremely important to me to provide all of this content without relying on paid ads.
[00:11:47.840 --> 00:11:51.200] To do this, our work is made entirely possible by our members.
[00:11:51.200 --> 00:11:58.160] And in return, we offer exclusive member-only content and benefits above and beyond what is available for free.
[00:11:58.160 --> 00:12:05.440] So if you want to take your knowledge of this space to the next level, it's our goal to ensure members get back much more than the price of the subscription.
[00:12:05.440 --> 00:12:08.320] Premium membership includes several benefits.
[00:12:08.320 --> 00:12:16.480] First, comprehensive podcast show notes that detail every topic, paper, person, and thing that we discuss in each episode.
[00:12:16.480 --> 00:12:20.480] And the word on the street is: nobody's show notes rival ours.
[00:12:20.480 --> 00:12:24.480] Second, monthly Ask Me Anything or AMA episodes.
[00:12:24.480 --> 00:12:36.280] These episodes are comprised of detailed responses to subscriber questions, typically focused on a single topic and are designed to offer a great deal of clarity and detail on topics of special interest to our members.
[00:12:36.280 --> 00:12:40.040] You'll also get access to the show notes for these episodes, of course.
[00:12:40.040 --> 00:12:46.200] Third, delivery of our premium newsletter, which is put together by our dedicated team of research analysts.
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[00:13:06.280 --> 00:13:16.520] Fifth, The Qualies, an additional member-only podcast we put together that serves as a highlight reel featuring the best excerpts from previous episodes of The Drive.
[00:13:16.520 --> 00:13:21.880] This is a great way to catch up on previous episodes without having to go back and listen to each one of them.
[00:13:21.880 --> 00:13:25.080] And finally, other benefits that are added along the way.
[00:13:25.080 --> 00:13:33.400] If you want to learn more and access these member-only benefits, you can head over to peteratimd.com forward slash subscribe.
[00:13:33.400 --> 00:13:38.920] You can also find me on YouTube, Instagram, and Twitter, all with the handle PeterAtiaMD.
[00:13:38.920 --> 00:13:44.360] You can also leave us review on Apple Podcasts or whatever podcast player you use.
[00:13:44.360 --> 00:13:54.440] This podcast is for general informational purposes only and does not constitute the practice of medicine, nursing, or other professional healthcare services, including the giving of medical advice.
[00:13:54.440 --> 00:13:57.320] No doctor-patient relationship is formed.
[00:13:57.320 --> 00:14:03.080] The use of this information and the materials linked to this podcast, is at the user's own risk.
[00:14:03.080 --> 00:14:09.320] The content on this podcast is not intended to be a substitute for professional medical advice, diagnosis, or treatment.
[00:14:09.320 --> 00:14:19.680] Users should not disregard or delay in obtaining medical advice from any medical condition they have, and they should seek the assistance of their healthcare professionals for any such conditions.
[00:14:19.680 --> 00:14:23.120] Finally, I take all conflicts of interest very seriously.
[00:14:23.120 --> 00:14:35.920] For all of my disclosures and the companies I invest in or advise, please visit peteratimd.com forward slash about, where I keep an up-to-date and active list of all disclosures.

Prompt 2: Key Takeaways

Now please extract the key takeaways from the transcript content I provided.

Extract the most important key takeaways from this part of the conversation. Use a single sentence statement (the key takeaway) rather than milquetoast descriptions like "the hosts discuss...". 

Limit the key takeaways to a maximum of 3. The key takeaways should be insightful and knowledge-additive. 

IMPORTANT: Return ONLY valid JSON, no explanations or markdown. Ensure:
- All strings are properly quoted and escaped
- No trailing commas
- All braces and brackets are balanced
Format: {"key_takeaways": ["takeaway 1", "takeaway 2"]}

Prompt 3: Segments

Now identify 2-4 distinct topical segments from this part of the conversation.

For each segment, identify:
- Descriptive title (3-6 words)  
- START timestamp when this topic begins (HH:MM:SS format)
- Double check that the timestamp is accurate - a timestamp will NEVER be greater than the total length of the audio
- Most important Key takeaway from that segment. Key takeaway must be specific and knowledge-additive.
- Brief summary of the discussion

IMPORTANT: The timestamp should mark when the topic/segment STARTS, not a range. Look for topic transitions and conversation shifts.

Return ONLY valid JSON. Ensure all strings are properly quoted, no trailing commas:
{
  "segments": [
    {
      "segment_title": "Topic Discussion", 
      "timestamp": "01:15:30",
      "key_takeaway": "main point from this segment",
      "segment_summary": "brief description of what was discussed"
    }
  ]
}

Timestamp format: HH:MM:SS (e.g., 00:05:30, 01:22:45) marking the START of each segment.

Prompt 4: Media Mentions

Now scan the transcript content I provided for ACTUAL mentions of specific media titles:

Find explicit mentions of:
- Books (with specific titles)
- Movies (with specific titles)  
- TV Shows (with specific titles)
- Music/Songs (with specific titles)

DO NOT include:
- Websites, URLs, or web services
- Other podcasts or podcast names

IMPORTANT: 
- Only include items explicitly mentioned by name. Do not invent titles.
- Valid categories are: "Book", "Movie", "TV Show", "Music"
- Include the exact phrase where each item was mentioned
- Find the nearest proximate timestamp where it appears in the conversation
- THE TIMESTAMP OF THE MEDIA MENTION IS IMPORTANT - DO NOT INVENT TIMESTAMPS AND DO NOT MISATTRIBUTE TIMESTAMPS
- Double check that the timestamp is accurate - a timestamp will NEVER be greater than the total length of the audio
- Timestamps are given as ranges, e.g. 01:13:42.520 --> 01:13:46.720. Use the EARLIER of the 2 timestamps in the range.

Return ONLY valid JSON. Ensure all strings are properly quoted and escaped, no trailing commas:
{
  "media_mentions": [
    {
      "title": "Exact Title as Mentioned",
      "category": "Book",
      "author_artist": "N/A",
      "context": "Brief context of why it was mentioned",
      "context_phrase": "The exact sentence or phrase where it was mentioned",
      "timestamp": "estimated time like 01:15:30"
    }
  ]
}

If no media is mentioned, return: {"media_mentions": []}

Full Transcript

[00:00:10.480 --> 00:00:16.000] Hey everyone, welcome to a sneak peek, Ask Me Anything, or AMA episode of the Drive podcast.
[00:00:16.000 --> 00:00:17.760] I'm your host, Peter Attia.
[00:00:17.760 --> 00:00:25.360] At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created.
[00:00:25.360 --> 00:00:30.880] Or you can learn more now by going to peteratiamd.com forward slash subscribe.
[00:00:30.880 --> 00:00:36.080] So without further delay, here's today's sneak peek of the Ask Me Anything episode.
[00:00:39.280 --> 00:00:42.240] Welcome to Ask Me Anything, episode 65.
[00:00:42.240 --> 00:00:45.200] I'm once again joined by my co-host, Nick Stenson.
[00:00:45.200 --> 00:00:47.760] In today's episode, we cover red light therapy.
[00:00:47.760 --> 00:00:50.560] It's a topic we get asked about all the time.
[00:00:50.560 --> 00:00:53.280] In fact, my wife asks me about it all the time.
[00:00:53.280 --> 00:00:56.240] So it was clear that it was time for an AMA.
[00:00:56.240 --> 00:01:02.160] In this conversation, we lay the foundation for what red light therapy is and why there is such an emphasis on it.
[00:01:02.160 --> 00:01:07.760] We then break down the various forms of red light therapy and their various treatments into whether or not I think they are beneficial.
[00:01:07.760 --> 00:01:12.320] In other words, we go through each application and review the data for them.
[00:01:12.320 --> 00:01:30.000] So these include red light therapy for aging in general, skin health and acne, wound healing, hair loss, eye health, exercise performance and recovery, metabolic health, general weight loss, spot fat loss, inflammation, injury rehab, and menstrual cramps for women.
[00:01:30.000 --> 00:01:36.080] So in other words, we go through each of these and do a detailed analysis of the literature.
[00:01:36.080 --> 00:01:46.800] We close this conversation by summarizing my overall takeaways for each use case and explain via a summary table that we created that breaks down everything you might want to know to understand this.
[00:01:46.800 --> 00:01:52.480] If you're a subscriber and you want to watch the full video of this podcast, you can find it on the show notes page.
[00:01:52.480 --> 00:01:57.840] If you're not a subscriber, you can watch a sneak peek of the video on our YouTube page.
[00:01:57.840 --> 00:02:01.960] So, without further delay, I hope you enjoy AMA number 65.
[00:02:07.000 --> 00:02:09.080] Peter, welcome to another AMA.
[00:02:09.080 --> 00:02:09.800] How are you doing?
[00:02:09.800 --> 00:02:10.040] Good.
[00:02:10.040 --> 00:02:11.560] Thanks for having me back.
[00:02:11.560 --> 00:02:12.360] Anytime.
[00:02:12.360 --> 00:02:13.320] Anytime.
[00:02:13.320 --> 00:02:18.680] So, today's AMA, we are going to focus on a single topic, which is red light therapy.
[00:02:18.680 --> 00:02:25.080] This is something we get asked about a lot, not only questions from the website and subscribers, but I know through your patients as well.
[00:02:25.080 --> 00:02:37.960] And so, we compiled all these questions and through this conversation, hopefully, going to cover what red light therapy is, how it can work, deep dive into some various claims out there around red light therapy.
[00:02:37.960 --> 00:02:50.280] This can include potential effect on skin health, wound healing, hair loss, eyesight, exercise performance, and recovery, metabolic health, fat loss, inflammation, chronic pain, and a lot more.
[00:02:50.280 --> 00:02:55.400] So, with all that said, anything you want to add before we get rolling into it?
[00:02:55.400 --> 00:02:56.680] Two unrelated things.
[00:02:56.680 --> 00:03:01.240] I notice you have a little visitor for the podcast today hanging out with you there.
[00:03:01.240 --> 00:03:04.520] Hopefully, he's interested, and this is something he'll like.
[00:03:04.520 --> 00:03:10.280] And secondly, I would add that my wife is specifically asking me these questions.
[00:03:10.280 --> 00:03:15.080] So, she's very keen to buy a whole bunch of red light things.
[00:03:15.080 --> 00:03:23.800] And I asked her to just hold off until we did the research for this episode so that we could at least have a sense of if there's value there, where it is.
[00:03:23.800 --> 00:03:25.640] I don't know if she's a subscriber, though.
[00:03:25.640 --> 00:03:29.000] So, if she's not, this might be the one that she subscribes for.
[00:03:29.000 --> 00:03:38.520] I respect that when your wife asks you medical questions, you say, Let me send you a podcast episode instead of telling her the answer like everyone else.
[00:03:38.520 --> 00:03:44.040] So, it's good to know you practice what you preach, even through your direct family.
[00:03:44.040 --> 00:03:44.480] Okay.
[00:03:44.760 --> 00:03:45.520] First question.
[00:03:45.760 --> 00:03:52.000] I think it's going to be helpful to just explain when we say red light therapy, what does that even mean?
[00:03:52.000 --> 00:03:57.840] Yeah, you can't do this without at least having some understanding of the physics and the principles.
[00:03:57.840 --> 00:04:05.920] that define light and waves come up over and over and over again as you try to evaluate the plausibility of the claims that are made here.
[00:04:05.920 --> 00:04:13.680] So when we're sitting here looking out at the world, we're looking at light and there's visible colors of light.
[00:04:13.680 --> 00:04:15.120] Maybe I should take a step back.
[00:04:15.120 --> 00:04:19.920] Light exists as waves and they're very short waves to be clear.
[00:04:19.920 --> 00:04:22.400] So sound waves are really, really long.
[00:04:22.400 --> 00:04:24.640] Light waves are really, really short.
[00:04:24.640 --> 00:04:32.000] And then obviously waves can get much, much shorter and you can get into UV, which we've talked about in detail on a previous podcast.
[00:04:32.000 --> 00:04:34.080] And then even shorter than that would be X-rays.
[00:04:34.080 --> 00:04:35.920] And then even shorter than that are gamma rays.
[00:04:35.920 --> 00:04:39.840] So as wavelengths get shorter, the energy gets more powerful.
[00:04:39.840 --> 00:04:57.920] But if we just focus on light, visible light runs the gamut from about 380 nanometers, which would be purple-ish, and then all the way at the longest end, about twice that 780 nanometers, is where red light is.
[00:04:57.920 --> 00:05:06.960] So when people talk about red light therapy, they're mostly talking about light that is in that very narrow band.
[00:05:06.960 --> 00:05:11.760] So for example, again, a white light is giving you all mixed across that entire range.
[00:05:11.760 --> 00:05:14.320] Red light would be more narrowly focused.
[00:05:14.320 --> 00:05:19.400] It's also important to understand that, and we'll talk about this a little bit today.
[00:05:19.400 --> 00:05:30.520] Phototherapy in general involves wavelengths across that entire band of visible light, but it also includes something called near-infrared.
[00:05:31.160 --> 00:05:38.840] So that basically runs the gamut from about 400 to 1100 nanometers.
[00:05:38.840 --> 00:05:57.480] So I think the easiest way to think about this is red light therapy, which runs about 620 to 780 nanometers, and then near infrared, which is right adjacent to that, the next thing up in terms of length, which is about 790 to 1400.
[00:05:57.800 --> 00:06:10.280] So again, if you forget everything else, just remember when people talk about red light therapy, they're talking about wavelengths that are just in that red visible area of 620 to 780.
[00:06:10.280 --> 00:06:15.080] And then often they talk about near-infrared as well, which is not visible.
[00:06:15.080 --> 00:06:21.640] To be clear, you don't see it, but it's just a little bit longer, 790 to 1400 nanometers.
[00:06:21.640 --> 00:06:31.000] We'll come back to this over and over again because there are some instances where the fact that you can't see it might actually make it a little more dangerous.
[00:06:31.000 --> 00:06:44.040] Double-clicking on red light therapy, can we explain a little bit more about what is special about it and why there's so much emphasis on it, as talked about for the various claims that we'll speak about today?
[00:06:44.360 --> 00:06:58.040] People who listened to our podcast on ultraviolet light may recall a distinction I made between UVA and UVB, which came down to the degree of penetration.
[00:06:58.040 --> 00:07:19.760] And so similarly, when you think about red light therapy, and you remember that the longer a wavelength, the more it can penetrate, albeit with less energy, what makes red light interesting is it is sort of at this sweet spot where it has some capacity to penetrate more so than other forms of visible light.
[00:07:14.920 --> 00:07:22.000] That's sort of part of what makes this interesting.
[00:07:22.240 --> 00:07:32.080] Now, the exact depth that's reached by the red light or the near-infrared is kind of a function of how the light beams are organized.
[00:07:32.080 --> 00:07:38.240] So, what is the amount of coherence, which is how much do the wavelengths line up with each other?
[00:07:38.240 --> 00:07:44.640] So, if the wavelengths are all coherent, the peaks and valleys are in the same place, it's going to have more penetrance.
[00:07:44.640 --> 00:07:48.800] And then, what's the extent to which they're all aligned in the exact same direction?
[00:07:48.800 --> 00:07:50.560] That's called collimation.
[00:07:50.560 --> 00:07:55.840] So, in other words, the light isn't spreading, but rather it's all pointed in the exact same direction.
[00:07:55.840 --> 00:08:10.080] And then, finally, you have the intensity, and we'll talk a little bit about the difference between watts and joules, because if people are looking at these devices, sometimes they give you information in watts, and sometimes they give you information in joules, which of course, there's a very clear relationship between them.
[00:08:10.080 --> 00:08:13.360] And, of course, broadly speaking, energy matters as well.
[00:08:13.360 --> 00:08:28.640] So, when you take all of that into account, though, the really important principle that I think gets perhaps missed when people evaluate these things is that for the most part, red light can't penetrate nearly as much as people think it can.
[00:08:28.640 --> 00:08:29.120] Okay.
[00:08:29.120 --> 00:08:39.760] If red light is being delivered by LEDs, which is the most common way that it is, it's going to be able to penetrate about two to three millimeters into skin.
[00:08:39.760 --> 00:08:48.160] Now, infrared light can go a little bit deeper, because remember, it's a longer wavelength, and it can reach probably five to 10 millimeters.
[00:08:48.160 --> 00:08:57.840] Now, if red light is delivered by a laser, because again, you now have a more focused form of light energy, it could penetrate significantly higher than that.
[00:08:57.840 --> 00:09:00.000] It could go from one to four centimeters.
[00:09:00.440 --> 00:09:08.280] So, again, keep in mind the way that the light is organized plays a significant role in the depth that it can penetrate.
[00:09:08.280 --> 00:09:27.560] Now, if you start to think about some of the applications we're going to talk about, when you start to think about red light therapy, just keep in the back of your mind: if something can only penetrate one to three millimeters, it's going to be difficult for it to have some of the profound effects that are sometimes claimed.
[00:09:27.560 --> 00:09:36.360] Even if something can penetrate 10 millimeters or a centimeter, which would be quite deep, it's not clear that that's going to be able to have a significant effect.
[00:09:36.360 --> 00:09:45.240] And so, as a general rule of thumb, the more superficial the application, the more plausible I think it's going to be as we go through these.
[00:09:45.560 --> 00:09:58.120] Last foundational question before we get to the various claims and where this could be beneficial or not is, in general, what happens when the tissue is exposed to red light?
[00:09:58.120 --> 00:10:01.080] This is an important and, as you said, foundational question.
[00:10:01.400 --> 00:10:12.680] So, to have any biologic effect, the light needs to be absorbed by some photosensitive molecule within the cell or tissue that it's hitting.
[00:10:12.680 --> 00:10:23.880] And so, the absorption of light by these photosensitive molecules, which are called chromophores, cause a localized chemical change or a photochemical reaction.
[00:10:23.880 --> 00:10:32.600] Now, the most interesting of these is probably something called cytochrome C oxidase, or CCO.
[00:10:32.600 --> 00:10:37.320] It's a component of the electron transport chain within mitochondria.
[00:10:37.320 --> 00:10:55.280] And generally speaking, most people who are proponents of red light therapy point to cytochrome C oxidase or CCO as the main target and therefore the mediating effect of the biologic impact of red light.
[00:10:55.280 --> 00:11:06.320] So red light and near-infrared wavelengths do seem to excite cytochrome C oxidase, and its activity then increases subsequent ATP production.
[00:11:06.320 --> 00:11:19.200] Conversely, blue and green wavelengths, remember these are shorter, less penetrant, but more powerful, seem to decrease the activity of CCO and subsequently decrease ATP production.
[00:11:19.280 --> 00:11:32.800] Now, kind of getting into various claims of where red light therapy can be beneficial or not, I think it'd help to maybe start with what do we know about the idea that red light therapy can combat aging as a whole.
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