Intro. [Recording date: May 18, 2026.]
Russ Roberts: It’s May 18th, 2026, and I’m thrilled to welcome back author Rowan Jacobsen. Last time, in October 2021, he shared insights from his book Truffle Hound, which turned out to be a fan favorite in our annual poll. This time, he’s here to discuss his latest work, In Defense of Sunlight: The Surprising Science of Sun Exposure.
Rowan, welcome back to EconTalk.
Rowan Jacobsen: Thanks, Russ. It’s great to be here again. Here’s hoping for another top spot this year!
Russ Roberts: We’ll see about that! You might need to employ some voting shenanigans like last time—just a little multiple-choice magic.
Rowan Jacobsen: Hey, it worked last time!
Russ Roberts: Today, we’re diving into health-related topics. Just a quick reminder: while I may have a Ph.D. in economics, I’m not dispensing medical advice here. As usual, take everything with at least a grain—or perhaps a mountain—of salt. Rowan’s take on sun exposure challenges long-held beliefs, so let’s get into it.
Rowan, what’s the central thesis of your book?
Rowan Jacobsen: The crux of my argument is that the accumulation of scientific knowledge has reached a point where we need to rethink the conventional wisdom regarding sun exposure. The guidelines of the past few decades no longer align with the latest scientific findings.
Russ Roberts: Many people, especially the younger generation, have been taught to view the sun as a villain, leading to skin cancer—a fact that, while scientifically supported, deserves a nuanced discussion. The prevailing advice is to avoid the sun, and if you must venture outdoors, slather on sunscreen and don protective clothing. Would you say that’s an accurate reflection of current attitudes?
Rowan Jacobsen: Absolutely. Over the years, the recommendations have only intensified. Yes, the sun can increase skin cancer risk, which we all acknowledge. Consequently, health authorities have advised minimizing sun exposure, and recently, the narrative has shifted towards virtually eliminating any unprotected exposure. This alarmist stance is why I felt compelled to write this book. The media has been promoting a blanket message to avoid the sun at all costs, regardless of individual circumstances, which doesn’t capture the evolving research.
Russ Roberts: A concise summary of your book might be: The sun is not inherently harmful; in fact, it can be beneficial. While there are risks, informed individuals should understand these trade-offs. Does that reflect your argument?
Rowan Jacobsen: Yes, exactly! When you referred to the sun as a killer, I wanted to interject that it’s also a source of health and vitality, a perspective that has been largely overlooked.
Research now provides robust evidence that moderate sun exposure can enhance health in various direct and indirect ways, which is often excluded from discussions. When we’re told the sun is dangerous because it raises skin cancer risk, that’s true, but it’s only one aspect of overall health and longevity.
To illustrate, consider this metaphor: if orthopedists warned against exercise due to the risk of knee injuries, suggesting that people avoid physical activity entirely, they would neglect the broader health benefits of exercise.
Russ Roberts: Before reading your book, I might have thought sunlight was only good for improving mood, like how people often say, “Get outside in the morning light for a mood boost.” We’re all aware—especially in regions with long winters—of how sunlight can impact emotional health.
However, your book reveals more compelling insights, particularly regarding sunlight’s potential roles in skin, heart, and autoimmune health. Admittedly, my skepticism kicks in when I hear such claims, particularly as they appear to contradict the dominant narrative. Yet, the volume of research behind your assertions is substantial, indicating this isn’t mere quackery.
Rowan Jacobsen: That’s what initially drew me to this topic, prompting me to dedicate a book to it. There’s decades of research across various disciplines highlighting sunlight’s benefits, yet these findings often go unacknowledged in public discourse. Scientific specialization means researchers publish studies suggesting potential benefits of sun exposure without furthering the conversation, resulting in these studies fading into obscurity.
So, when I noticed a wealth of research on this topic, it became clear that no one was synthesizing this information into a coherent understanding, which motivated my focus on the subject.
And, being skeptical is important. I shared your initial hesitation too, as claims diverging from expert advice prompt questions about validity. I hope my book stimulates a broader dialogue rather than presenting a definitive conclusion.
Russ Roberts: It’s wise to remain skeptical of expert opinions. As you mentioned, the sunscreen industry is massive; there’s substantial profit to be made. It’s crucial to approach this with balance and thoughtfulness, especially considering the complexities of health.
Russ Roberts: One of the intriguing aspects of your book is the historical perspective on how societal views of sunlight have evolved. In the early 20th century, there was a romanticized belief in sunlight’s healing powers—termed heliotherapy. This belief gained traction as sunlight was associated with combating diseases like tuberculosis. Can you elaborate on this movement and its significance?
Rowan Jacobsen: Absolutely! I discovered a captivating history I wasn’t initially aware of. In the early 1900s, the concept of heliotherapy was flourishing in both Europe and the United States, largely in response to tuberculosis, which was a significant health crisis at the time. In fact, tuberculosis accounted for one in every four deaths in Europe during the late 19th century.
A doctor from the Faroe Islands made a groundbreaking discovery that concentrated sunlight could combat cutaneous tuberculosis, leading to its widespread acceptance. Simultaneously, the rise of rickets—a disease linked to insufficient sunlight exposure—was recognized. Children in urban tenements, lacking sunlight, were developing rickets, which caused severe developmental issues.
Both conditions could be treated with sunlight, leading to the establishment of heliotherapy clinics across Europe and the U.S. People flocked to sunny locales like the Swiss Alps, not just for the fresh air, but for the therapeutic benefits of sunlight. The medical community embraced this idea, endorsing sunlight as essential for overall health, leading to radical changes in public health policy and educational environments.
Russ Roberts: Let’s discuss skin cancer prevalence, then we can return to Vitamin D. Skin cancer rates have surged globally, particularly in the U.S. However, the reasons behind this increase are complex and often overlooked. Can you clarify what we know and the nuances involved?
Rowan Jacobsen: Skin cancer encompasses three main types: squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and melanoma. The latter accounts for approximately 2% of skin cancer cases, but it’s the most concerning due to its associated mortality rates.
Historically, SCCs and BCCs were not common prior to World War II, primarily affecting sailors and farmers. However, post-war, there was a dramatic rise in skin cancer cases, partly due to improved public health measures allowing people to live longer, but also because of increased scrutiny and diagnosis. As life expectancy increased, more individuals were at risk of developing skin cancer simply due to aging.
With the rising skin cancer rates, a panic ensued, leading the medical community to blame increased sun exposure and advocate for sun avoidance. This narrative has intensified over the decades.
Russ Roberts: However, this explanation is complicated by the fact that 20th-century lifestyles shifted significantly. People spent more time indoors, with the rise of office work and a decrease in outdoor professions. There’s also the issue of increased diagnoses—can you speak to this?
Rowan Jacobsen: Here’s a fascinating tidbit: the best predictor of whether someone will be diagnosed with skin cancer isn’t sun exposure, but rather the number of dermatologists in their county. The more dermatologists there are, the more diagnoses you’ll see. As we become more vigilant in identifying skin issues, we inevitably discover more cases.
While this increased vigilance can lead to earlier diagnoses, which is beneficial, it’s essential to recognize that this trend contributes significantly to the rising incidences of skin cancer. The early studies on skin cancer rates often lacked context, erroneously assuming that people in the past were less exposed to the sun. In reality, historical records show that sun exposure was common, particularly among those living in coastal areas.
Russ Roberts: To summarize, the rise in skin cancer rates, particularly between carcinoma and melanoma, may be more attributed to increased diagnoses rather than a true epidemic. What do we know about mortality rates associated with skin cancer?
Rowan Jacobsen: When it comes to melanoma, there’s widespread agreement among researchers that overdiagnosis is a significant issue. While it’s crucial to identify potential melanomas, many diagnosed cases might not pose a threat. Interestingly, mortality rates associated with melanoma have remained stable over the last several decades, despite the rising incidence of diagnoses—an indicator of overdiagnosis.
Studies have demonstrated that dermatologists are increasingly lenient in their classifications of what constitutes melanoma, contributing to rising statistics. However, catching potential melanomas early is still beneficial, as it allows for timely treatment.
Russ Roberts: The introduction of sunscreen to the market coincides with this uptick in skin cancer. Historically, sunscreen was a modern invention, and prior to its existence, people relied on natural methods to protect themselves from the sun. Why hasn’t the widespread use of sunscreen mitigated the skin cancer epidemic?
Rowan Jacobsen: This is an inconvenient truth that has lingered around the sunscreen industry for quite some time. Despite the rise in sunscreen use, skin cancer rates continue to climb. Epidemiological studies often correlate increased sunscreen usage with higher skin cancer incidences, but it’s essential to consider who typically uses sunscreen—those with fairer skin who may already be at higher risk.
This creates a classic case of reverse causation—those who use more sunscreen often spend more time in the sun. However, it’s clear that sunscreen isn’t providing the protective benefits we were led to believe.
Russ Roberts: Let’s delve into SPF. What exactly does SPF represent, and why might its implications be more complex than we assume?
Rowan Jacobsen: SPF stands for Sun Protection Factor. It indicates how much longer you can stay in the sun without burning compared to not using sunscreen. For instance, if you usually burn after 10 minutes without sunscreen, applying SPF 30 allows you to stay out for 300 minutes without burning. However, this only applies to UVB rays, which are primarily responsible for sunburn.
Historically, early sunscreens focused solely on UVB protection, neglecting UVA rays, which also contribute to skin cancer risk. As our understanding of UV exposure evolved, it became clear that blocking both types of rays is essential for effective sun protection.
Russ Roberts: The improvements in sunscreen formulations should have made a difference. What’s the current state of sunscreen effectiveness?
Rowan Jacobsen: Recent advancements have indeed improved modern sunscreens, particularly in Europe and Asia, where formulations tend to be superior to those available in the U.S. Newer sunscreens effectively block both UVB and UVA rays, and observational studies are beginning to show better outcomes associated with contemporary sunscreen use.
Although the early formulations were often ineffective and sometimes counterproductive, the newer products are more reliable. They should be considered a complement to a comprehensive sun safety strategy.
Russ Roberts: We’ve discussed Vitamin D in the context of sun exposure. What’s the latest understanding of its importance, especially considering the challenge of obtaining sufficient levels through supplements?
Rowan Jacobsen: The narrative around Vitamin D has evolved. While observational studies indicated that low Vitamin D levels correlate with higher rates of various diseases, clinical trials have often failed to demonstrate that raising Vitamin D levels through supplementation effectively reduces these risks.
This conundrum suggests that while natural sunlight exposure may yield health benefits, artificially raising Vitamin D levels via pills might not replicate those advantages. The implication is that we may be missing out on other beneficial effects of sunlight beyond just Vitamin D.
Russ Roberts: Your book contains personal anecdotes that highlight the transformative power of sunlight. Can you share your thoughts on how sunlight affects our overall well-being, particularly in the context of modern life?
Rowan Jacobsen: Absolutely. Understanding the science behind sunlight and becoming more comfortable with it can enhance daily life. Realizing that fears surrounding sun exposure may be unnecessarily exaggerated can significantly improve one’s quality of life.
From an evolutionary standpoint, humans have thrived under sunlight for millennia. It’s worth questioning whether the contemporary fear of sunlight is justified, especially given that our ancestors spent significant time outdoors, benefiting from natural light.
Russ Roberts: As we conclude, what practical advice do you have for individuals regarding sun exposure? It’s essential to navigate the balance between health benefits and risks.
Rowan Jacobsen: My advice is to embrace moderation. Zero sun exposure is detrimental to health, just as sunburns are harmful. A pragmatic approach is to avoid burning while still allowing for incidental sun exposure, which can be beneficial. Each individual’s circumstances—such as skin tone and geographical location—should inform their sun exposure strategy.
People with darker skin can tolerate more sun than those with fair skin, who should be particularly cautious. The general recommendations regarding sun safety often default to the most vulnerable populations, but we’re beginning to understand the need for tailored advice.
Russ Roberts: My guest today has been Rowan Jacobsen. His book, In Defense of Sunlight, offers valuable insights into the multifaceted relationship we have with sunlight. Thank you, Rowan, for joining me on EconTalk.
Rowan Jacobsen: Thank you, Russ! It was a pleasure.
