Sunny side up
Diving into the research, history, and current directions of heliotherapy and sunscreen
Top of the morning, sapien. Welcome to Common Sense Medicine, where I try and keep you up to date on the latest and greatest in longevity science.
This week, I’m talking about heliotherapy. It’s a topic which I wanted to cover with nuance (as much nuance as one can in a newsletter). In fact, I learned some new things throughout this newsletter about the sun—and light in general—and what that could mean for overall wellness. What I’ll cover is threefold: (1) emerging observations about light therapy in animal studies, (2) what the FDA has found about sunscreen ingredients, and (3) how does light exposure (primarily from the sun) impact mood.
Other items on the differential:
My recent jet lag protocol, helping me avoid disruptions in my sleep schedule
Physiologic protein responses and implications for dietary protein consumption
Blood-based biomarkers of cerebrovascular disease for timely management
THE WEEKLY DOSE
Been there, sun that
It’s no surprise that light exposure is important. This has already been codified in traditional healthcare for quite some time now. Many people are familiar with the notion that seasonal affective disorder (SAD) is primarily based around the lack of exposure to sunlight in the winter months. In fact, the treatment for SAD is to get outside, and get more sunlight.
With our largely indoor lifestyles, unfortunately, that is becoming less and less popular. We don’t go outside nearly as much as we used to—over 60 percent of adults report spending less than 5 hours per week outside. The COVID-19 pandemic drove people indoors which caused a 3-fold increase in the prevalence of depression in the U.S.
I think that there’s a narrative case to be made that going outdoors makes us happier and healthier in the long run, and that making sure that we get light exposure can help us even if we don’t suffer from SAD. But for me, I don’t think that’s enough—there’s also real harms associated with sun exposure, such as skin cancers and DNA damage which can occur due to the excess of sun exposure.
The historical case for light therapy
Neils Ryberg Finsen was a young man born in 1860 who developed Pick’s disease, a debilitating and fatiguing disease. He vowed to spend a lot of time in the sun, a habit which caused him to feel better and more energetic. In 1896, he noticed a case report of two patients with Lupus vulgaris—a cutaneous form of tuberculosis—being essentially cured through 2 sessions of light therapy.
At the time, tuberculosis did not have any known cure because the first antibiotics to treat tuberculosis would emerge in 1943. Finsen was determined to find out the curing properties of light, from a scientific lens. He was able to eliminate the short-waves of the light, concentrate it, and restrict the blood flow of patients via an invented device to provide treatment for approximately 804 patients. Out of these, over 70 percent were cured or nearly cured from light alone.
For his efforts, he was awarded the 1903 Nobel Prize in medicine. This historical context is not lost on me as I was researching this topic—that the UVA and UVB rays may not only provide mental health benefits (i.e., protection against SAD) but also very real, tangible physical benefits such as being bactericidal.
Chads say that light does everything under the sun
When I was trying to research the Chad Health portion of this newsletter, I got pulled in so many directions to take this discussion. My takeaway is that Chads generally believe that “more sun is better, but make sure you use the right type of sunscreen to protect yourself.”
Obviously, it doesn’t capture all of the nuance which they talk about (and you can click on the links to learn more their opinions). There are studies, mostly animals or in vitro studies, which show that there is increase in male sex hormones and nitric oxide when there is exposure to sunlight, which Chads use to justify their love for sunlight.
Chads also mention that sunscreen is not the devil—but you have to make sure that it isn’t disrupting your endocrine system and causing an increase in estrogenic derivatives. The FDA has done studies in 2019 and 2020 which show that common active ingredients in sunscreen (avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate) are systemically absorbed above a threshold which is generally recognized as safe and effective (GRASE).
Chads also believe that the right type of sunscreen is important—Dr. Paul Saladino mentions that avoidance of seed oils helps with preventing sunburn and using topical cholesterol can prevent sun damage.
Trads believe in sunscreen and also extol the importance of timing
Dr. Brian Diffey, an expert in sunscreen science, mentioned that the FDA study which showed active ingredients in the plasma was flawed because the subjects were putting on the equivalent of 2 bottles on sunscreen on a day. Also, another one of his criticisms of the Chad Health philosophy is that whichever UV filter you are using, you won’t be putting it on in nearly enough quantities—nor do we know the long-term effects of sunscreen. Even further, the organic (avobenzone, etc.) and inorganic (zinc oxide) flavor of sunscreen filters all end up in the blood, the jury is still out on whether that poses a real risk and in what dose.
Moving onto the other part of the article, light exposure via the sun is also very important not only because of the physical benefits of sex hormone production / nitric oxide, but also for the mood benefits. Dr. Peter Attia and Dr. Andrew Huberman recently had a journal club podcast where they discussed a Nature Mental Health article which mentioned how daytime light exposure and night-time dark exposure helped decrease self harm, PTSD, hypomania / mania, and MDD.
They mentioned that the 100,000 lux sun light at noon isn’t particularly what you want to get, but rather the solar light at the beginning and ends of the day, when the “solar angle” is low. The study, which used 85,000 people (on the older side, admittedly, in the 50s and 60s) and measured ambient light exposure with accelerometers, controlled for activity levels.
Interestingly enough, in the hospital, light exposure at night and less light exposure during the day causes iatrogenic harm: sometimes patients undergo ICU psychoses, becoming delirious because it’s hard to get cues about when to wake and sleep. Also, it probably doesn’t help that you’re getting multiple CBCs and CMPs at all hours of the day in the ICU, along with vital checks. In fact, the more time you spend outdoors, the better your sleep cycle gets—according to a 400,000-strong observational study from the UK Biobank.
Trad Health enthusiasts understand that the UV part of the sunlight spectrum has beneficial effects in small doses, but don’t endorse it nearly as much as the Chads do. Short wavelength UVB and longer wavelength UVA induce vitamin D production and other chemicals that protect skin cells. Furthermore, the UV radiation is anti-inflammatory, immune suppressing, and anti-proliferative. The daylight part of the sunlight spectrum can also be useful in the treatment of skin conditions, for example in combination with the photosensitizing agent, methyl aminolevulinic acid, for "daylight" photodynamic therapy (PDT) to treat actinic keratoses. One physician even talked about how heliotherapy helped his patient wean off of oxygen when suffering from COVID-19.
My takeaway: get outside as much as you can, but put on some sunscreen
I think that the sun really does have healing power. There’s no beating around the bush that the sun is very very important, and that avoiding the sun at all times will impact your sleep, your physical health, and your mental health. You’re playing a dangerous game if you haven’t seen the sun in a few days, because it can affect how you think (crazily enough). Where I don’t agree with the Chad Health narrative is where they deny the real benefits of sunscreen. I haven’t seen enough evidence to eschew sunscreen in favor of tallow, largely because the concentration in the plasma doesn’t come near the amount that I use for my sunscreen.
Furthermore, I really agree with Dr. Huberman’s recommendation to get more sun in the morning and night. It avoids the chance to get sunburn, while also satisfying the sunlight requirement. I am definitely using that more, especially since I have left my sunny vacation and now I’m back in the cold and the dark.
THE PRESCRIPTION
My Jet Lag Protocol: I used this jet lag protocol by Dr. Peter Attia to allow myself to adjust to a half-day time difference. It worked wonders!
One-minute-a-day focus: Based on Dr. Andrew Huberman’s focus principle (focus on one point), this website helps you do exactly that
Don’t let them stop you: One of my favorite YouTubers is trying to rehab his foot. I think this is a great video if you’re nursing an injury.
FIGURE OF THE WEEK
The upshot: Protein metabolism can be stretched to longer limits (i.e., a higher dose of protein > 70 g) if the type of protein is changed (i.e., from whey to casein)
Context: As Dr. Peter Attia explains in his post (See Source, Original Article)
The work by Trommelen et al. does not contradict conventional wisdom regarding protein utilization, but rather, it helps to provide valuable nuance. Although we can’t conclude from this study that anabolic responses to protein intake have no upper limit, the data reveal that “maximum” AA utilization for protein synthesis – as determined from earlier studies with whey protein – may be stretched depending on the form of protein consumed, potentially to a much higher ceiling than previously imagined.
JOURNAL CLUB
Rapamycin review: A review of rapamycin and why it’s such a great drug. But is it ready for prime time?
Show me who you really are: Finding blood-based biomarkers is hard, especially for one of the most elusive diseases on the planet.
Don’t eat: Fasting helps mimic an earlier age phenotype in 2 clinical trials with 140 participants, although it can cause lower lean body mass / reduction in weight.
REMEMBER, IT’S JUST COMMON SENSE.
Thanks so much for reading! Let me know what you thought by replying to this email.
See you next week,
Shree (@shree_nadkarni)