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In Defense of Sunlight: The Surprising Science of Sun Exposure
Upending everything we thought we knew about sun exposure, this “dazzling book” (Nature) explains the many health benefits of light and offers easy ways we can all incorporate more of it into our lives.
For decades, we’ve been told that the healthiest relationship with the sun is no relationship at all—that we should hide from direct sunlight or face the consequences. But in this groundbreaking investigation, acclaimed journalist Rowan Jacobsen presents the growing body of medical research on the substantial health benefits of appropriate sun exposure.
In this resounding call to return to common sense, Jacobsen offers seven words of Get sun. Not too much. Go outside. Weaving together decades of scientific research, this “eye-opening investigation” (Publishers Weekly) confirms what many of us instinctually moderate sun exposure isn’t something to fear—it’s what we need. In fact, sunlight is one of the simplest and most equitable treatments for a variety of health issues, from poor sleep and depression to high blood pressure and heart disease.
Part scientific examination, part cultural reckoning, In Defense of Sunlight not only traces how our misguided approach to sun avoidance developed, and how better science is now overturning those beliefs, it also offers practical advice for reaping the benefits of sun without the risks. “Clear-eyed” (The Wall Street Journal), thoroughly researched, and passionately presented, this “fantastic book” (Here & Now) can help everyone to discover one of nature’s best balms—right outside our door.
For decades, we’ve been told that the healthiest relationship with the sun is no relationship at all—that we should hide from direct sunlight or face the consequences. But in this groundbreaking investigation, acclaimed journalist Rowan Jacobsen presents the growing body of medical research on the substantial health benefits of appropriate sun exposure.
In this resounding call to return to common sense, Jacobsen offers seven words of Get sun. Not too much. Go outside. Weaving together decades of scientific research, this “eye-opening investigation” (Publishers Weekly) confirms what many of us instinctually moderate sun exposure isn’t something to fear—it’s what we need. In fact, sunlight is one of the simplest and most equitable treatments for a variety of health issues, from poor sleep and depression to high blood pressure and heart disease.
Part scientific examination, part cultural reckoning, In Defense of Sunlight not only traces how our misguided approach to sun avoidance developed, and how better science is now overturning those beliefs, it also offers practical advice for reaping the benefits of sun without the risks. “Clear-eyed” (The Wall Street Journal), thoroughly researched, and passionately presented, this “fantastic book” (Here & Now) can help everyone to discover one of nature’s best balms—right outside our door.
Audible Audio
First published June 16, 2026
About the author
Rowan Jacobsen
21 books123 followersRowan Jacobsen is the James Beard Award-winning author of A Geography of Oysters: The Connoisseur’s Guide to Oyster Eating in North America, Fruitless Fall: The Collapse of the Honey Bee and the Coming Agricultural Crisis, and The Living Shore, about our ancient connection to estuaries and their potential to heal the oceans. He has written for the New York Times, Newsweek, Harper’s, Outside, Eating Well, Forbes, Popular Science, and others, and his work has been anthologized in The Best American Science and Nature Writing and Best Food Writing collections. Whether visiting endangered oystermen in Louisiana or cacao-gathering tribes in the Bolivian Amazon, his subject is how to maintain a sense of place in a world of increasing placelessness. His 2010 book, American Terroir, was named one of the Top Ten Books of the Year by Library Journal. His newest, Shadows on the Gulf: A Journey Through Our Last Great Wetland, was released in 2011. His Outside Magazine piece “Heart of Dark Chocolate” received the 2011 Lowell Thomas Award from the Society of American Travel Writers for best adventure story of the year. He is a 2012 Alicia Patterson Foundation fellow, writing about endangered diversity on the borderlands between India, Myanmar, and China.
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Displaying 1 - 30 of 62 reviews
June 4, 2026
This is really well argued book with easy to follow science. I liked the read and it made me revisit much of my thinking around sun exposure. Persuasive. Straightforward.
September 13, 2026
I read hundreds of books a year and science books are among my favorites, but it can be hard to find ones that meet all of my requirements. Every couple of years I find one that is the perfect combination of rigorous research, new information (at least parts of it or at least to the layperson), fascinating science and an actually enjoyable voice (Never Home Alone was a previous home run for me). This one excelled in every aspect. It’s one of those books that I will talk about with so many friends and family members, and one that I will tell everyone they have to read.
Other reviewers have done a good job of summarizing some of the research, recommendations and findings in the book but it really isn’t enough. Just read it. It’s an enjoyable read and a must for doctors, parents, scientists, public policy professionals, and any of us who happen to have bodies.
I read a digital ARC of this book via netgalley.
Other reviewers have done a good job of summarizing some of the research, recommendations and findings in the book but it really isn’t enough. Just read it. It’s an enjoyable read and a must for doctors, parents, scientists, public policy professionals, and any of us who happen to have bodies.
I read a digital ARC of this book via netgalley.
June 23, 2026
When asked what's the source of all life on Earth, one could do much worse than point a confident finger at the Sun. During our daily grind, we don't give nearly enough credit to the sun, and often fail to recognize how deeply entrenched and intricate that star is in our very being. It not just gives life, but does wonders for sustaining it, protecting it, nurturing it, and when almost everything else fails - repairing it.
To say that the Sun finally as its day in the sun, would be a little too on the nose, but it is true that humanity's understanding of the ways in which our sun impacts and influences our lives has grown by leaps and bounds in the recent decades. Taking a brief trip into the prehistoric appearances of the sun, the book quickly begins to lay down facts, often ably propped up by scientific research or scientifically driven studies. We begin auspiciously enough, with the original halcyon days of field of heliotherapy, when the sun was indeed considered a certified treatment for such dreaded diseases like tuberculosis and pneumonia. This is where the book lays a strong foundation into the social stances that gave rise to the field, and that also subsequently supported those approaches. Of course, unlike other medical studies, the problem with studies to do with the medical or medicinal properties of the sun is that you can't tweak it from one round to another, and it is very difficult to isolate what in the sun's rays is harmful and what is beneficial. State sponsorship for such studies has always been rather weak, but there are some recent leader nations, who have been quick to realize possible benefits, and how to provide suitable scientific guidance to an open-minded, and educated populace.
A little before the middle of the book, sunscreen makes an appearance, with the best of intentions - the book is quick to point out, but soon creates an oversimplified and rather myopic view of the benefits of sunscreen, that coupled with the supposed benefits of UV in specific and sunlight in general, made a whole generation literally forget what the sun had come to mean to centuries of mankind history before it.
The author cites study after study that has provided incremental but concrete evidence that the sun's rays contain elements that benefit most of mankind, on most days, in the most ways. While sunburn is acknowledged as being harmful, the book makes an impassioned plea to consider changing that messaging to a more nuanced one, that even while highlighting the benefits of sunscreen also reminds that sunlight itself is not harmful. Life on Earth has evolved over billions of years, and it has had all that time to refine and re-refine how to make the best use of the single biggest source of heat and light on this planet, that is literally endless and absolutely free.
The last couple of chapters are about an experiment the author subjected himself to, and - in my opinion, that is an absolute delight. This is where this science treatise becomes a science memoir, and manages to demonstrate beyond much doubt the absolute dependency our human body has on natural sunlight, and how our circadian rhythm must have developed and first recognized for what it truly is - our body's response to best utilize the most abundant natural resource available to it - pure, unadulterated sunlight.
A fantastic, immensely erudite and well researched book into the life giving benefits of the biggest and brightest star in our terran sky.
My thanks to Netgalley, Scribner and the author for providing an eARC. The review is wholly mine.
To say that the Sun finally as its day in the sun, would be a little too on the nose, but it is true that humanity's understanding of the ways in which our sun impacts and influences our lives has grown by leaps and bounds in the recent decades. Taking a brief trip into the prehistoric appearances of the sun, the book quickly begins to lay down facts, often ably propped up by scientific research or scientifically driven studies. We begin auspiciously enough, with the original halcyon days of field of heliotherapy, when the sun was indeed considered a certified treatment for such dreaded diseases like tuberculosis and pneumonia. This is where the book lays a strong foundation into the social stances that gave rise to the field, and that also subsequently supported those approaches. Of course, unlike other medical studies, the problem with studies to do with the medical or medicinal properties of the sun is that you can't tweak it from one round to another, and it is very difficult to isolate what in the sun's rays is harmful and what is beneficial. State sponsorship for such studies has always been rather weak, but there are some recent leader nations, who have been quick to realize possible benefits, and how to provide suitable scientific guidance to an open-minded, and educated populace.
A little before the middle of the book, sunscreen makes an appearance, with the best of intentions - the book is quick to point out, but soon creates an oversimplified and rather myopic view of the benefits of sunscreen, that coupled with the supposed benefits of UV in specific and sunlight in general, made a whole generation literally forget what the sun had come to mean to centuries of mankind history before it.
The author cites study after study that has provided incremental but concrete evidence that the sun's rays contain elements that benefit most of mankind, on most days, in the most ways. While sunburn is acknowledged as being harmful, the book makes an impassioned plea to consider changing that messaging to a more nuanced one, that even while highlighting the benefits of sunscreen also reminds that sunlight itself is not harmful. Life on Earth has evolved over billions of years, and it has had all that time to refine and re-refine how to make the best use of the single biggest source of heat and light on this planet, that is literally endless and absolutely free.
The last couple of chapters are about an experiment the author subjected himself to, and - in my opinion, that is an absolute delight. This is where this science treatise becomes a science memoir, and manages to demonstrate beyond much doubt the absolute dependency our human body has on natural sunlight, and how our circadian rhythm must have developed and first recognized for what it truly is - our body's response to best utilize the most abundant natural resource available to it - pure, unadulterated sunlight.
A fantastic, immensely erudite and well researched book into the life giving benefits of the biggest and brightest star in our terran sky.
My thanks to Netgalley, Scribner and the author for providing an eARC. The review is wholly mine.
August 25, 2026
I’ve had some issues with sun damage the past few months and in the few hours I haven’t spent in dermatologists’ offices, I have developed a tendency to avoid my beloved Southern California sunlight, wanting to dive under a bush, a hedge, a car, or any solid object that might shield me from the so-called poisonous rays that might kill me. I’ve been feeling a little like Spike in BtVS, when he was trying to get from place to place in the daytime, as the blanket he’s grabbed for cover smolders and threatens to burst into flame.
I thought this book was outstanding. Chock-full of great information, entertainingly written, not the least bit dry or academic, and it was comforting to learn a lot of information that will be useful to me in the future.
Science and culture writer Rowan Jacobsen draws upon the latest science and input from dermatologists and other medical professionals to question the value of the of the current strident messaging that emphasizes the harmful effects of the sun. In fact, there are many important and vital beneficial aspects of exposure to sunlight that we are missing when we smother ourselves in sunscreen and extra clothing and hide from the sun too obsessively. There is a strong possibility that we are increasing our risks of other even more dangerous medical conditions as we obsess about avoiding skin cancer, when in fact only one kind of skin cancer (melanoma) is usually life-threatening, and then the serious risk is usually only for people with the fairest complexions.
Not all rays are created equal. The UVA we’re used to dodging is only one type, and Jacobsen clearly discussed the others and why we need them. Our mitochondria seem to like infrared light a lot, apparently. In addition to encouraging a more measured approach to fear of the sun in terms of disease, the science is showing sun avoidance may be limiting our general wellness, energy levels, moods, cognition, sleep quality, and productivity by divorcing our lives from circadian rhythms. Jacobsen also looks at the relationship of Vitamin D and nitrate oxide to sunlight and the nuances of their sources and benefits.
For the more scientifically inclined, there is a nifty little eight-page glossy illustrated section in the center of the book called “A Light Primer: Some Notes on the Physics of Photons.” And there are 51 pages of Glossary, Resources, and Notes at the back to refer to for further reading.
Certainly caution should be employed to avoid the harmful kind of rays when warranted, and Jacobsen is sure to point this out. But the modern messaging of “stay out of the sun, stay out of the sun! (or you’re going to die!)” may be over-zealous to the point of being harmful. “A one-size-fits-all approach isn’t productive,” as University of Texas dermatologist Adewole Adamson says. And anthropologist Nina Jablonski claims that overall public health would improve much more by relaxing this guideline than by enforcing it.
I know I will be adjusting my habits to be more accepting of sensible sunlight. Before this week's searing heat wave, I even had breakfast one day out on my balcony, soaking up the moderate morning light, with the butterflies playing among the blooming pink and white crepe myrtle trees below. Just lovely!
I thought this book was outstanding. Chock-full of great information, entertainingly written, not the least bit dry or academic, and it was comforting to learn a lot of information that will be useful to me in the future.
Science and culture writer Rowan Jacobsen draws upon the latest science and input from dermatologists and other medical professionals to question the value of the of the current strident messaging that emphasizes the harmful effects of the sun. In fact, there are many important and vital beneficial aspects of exposure to sunlight that we are missing when we smother ourselves in sunscreen and extra clothing and hide from the sun too obsessively. There is a strong possibility that we are increasing our risks of other even more dangerous medical conditions as we obsess about avoiding skin cancer, when in fact only one kind of skin cancer (melanoma) is usually life-threatening, and then the serious risk is usually only for people with the fairest complexions.
Not all rays are created equal. The UVA we’re used to dodging is only one type, and Jacobsen clearly discussed the others and why we need them. Our mitochondria seem to like infrared light a lot, apparently. In addition to encouraging a more measured approach to fear of the sun in terms of disease, the science is showing sun avoidance may be limiting our general wellness, energy levels, moods, cognition, sleep quality, and productivity by divorcing our lives from circadian rhythms. Jacobsen also looks at the relationship of Vitamin D and nitrate oxide to sunlight and the nuances of their sources and benefits.
For the more scientifically inclined, there is a nifty little eight-page glossy illustrated section in the center of the book called “A Light Primer: Some Notes on the Physics of Photons.” And there are 51 pages of Glossary, Resources, and Notes at the back to refer to for further reading.
Certainly caution should be employed to avoid the harmful kind of rays when warranted, and Jacobsen is sure to point this out. But the modern messaging of “stay out of the sun, stay out of the sun! (or you’re going to die!)” may be over-zealous to the point of being harmful. “A one-size-fits-all approach isn’t productive,” as University of Texas dermatologist Adewole Adamson says. And anthropologist Nina Jablonski claims that overall public health would improve much more by relaxing this guideline than by enforcing it.
I know I will be adjusting my habits to be more accepting of sensible sunlight. Before this week's searing heat wave, I even had breakfast one day out on my balcony, soaking up the moderate morning light, with the butterflies playing among the blooming pink and white crepe myrtle trees below. Just lovely!
July 21, 2026
Get sun. Not too much. Go outside.
- Rowan Jacobsen
This book makes an absolutely stellar argument that living our lives inside, with minimal sun exposure, is absolutely wrecking our health. This book might also make you feel a little bit like a complete and utter conspiracy theorist crackpot when you start nodding along to all the reasons why you should be getting more sun and not less, when that flies in the face of the messaging you've been receiving for the past 40-odd years.
The sun:
- helps regulate our hormones.
- reduces the risk of cardiovascular disease.
- regulates our circadian rhythms.
- improves our mood.
- improves our metabolic rate.
We're tall, hairless primates that evolved to walk around naked in the sunlight, such that even the microbiomes of our skin evolved with us to help protect us from the sun (along with our own melatonin production). But now we're being told that sun exposure will kill us all if we don't slather ourselves from head to toe in sunscreen. (There is even an article on the Washington Post this week with a sunscreen quiz, that insists you need to wear sunscreen indoors, because unspecified "some types" of UV rays can penetrate unspecified "some types" of glass.)
This book meanwhile, says, hey, actually, maybe go outside for 10-15 minutes or so a day, without sunscreen (humorously suggesting that 5 minutes of naked cartwheels in your backyard would do it, because you cause less skin damage when you expose more skin for less time).
In additional to all the benefits mentioned above, and it turns out that all the vitamin D goodness scientists are starting to really hone in on doesn't actually help if you consume vitamin D in supplement form, it only works when your body generates it through sun exposure.
The big thing though - don't get a sunburn. If you are strolling up to the beach for 12 hours when you normally live primarily indoors and live in a northern latitude, yes, slop on that sunscreen (but check the ingredients so if you go swimming you don't kill a coral reef). Wear a hat. Wear a long sleeved shirt. Sit in the shade. (Bonus points for sitting in the shade of lots of leafy green trees, due to the other reflected wavelengths of light.)
An even bigger takeaway is don't let your kids get sunburned. Childhood sunburns are much more strongly associated with melanoma than other burns.
Also, your ancestry might be dooming you anyway, or where you live. As someone with with Irish ancestry, lots of moles, that slight bit of natural red hair skulking in the shadows, and having spent over half my life living in a northern latitude, my odds for melanoma are already higher (this is without factoring in the childhood sunburns that I can remember).
Those of us living up north and with overall less sun exposure are also at significantly greater risk of multiple sclerosis.
I listened to this as an audiobook (entirely outside, mostly in the sun) but I've requested it from the library as an ebook too, because I want to look at Jacobsen's sources and dig a little deeper into some of the research on red light therapy.
Basically, this entire topic is utterly fascinating. I'm not throwing out my sunscreen, but I am going to approach my time in the sun more deliberately.
==
Book Bingo 2026: Eye-Opening
October 2, 2026
"Like most people, I’d had it drilled into me since childhood that the sun was bad news... But if we’re wired to seek out sunlight, there must be a reason..."
In Defense of Sunlight was an excellent look into the topic. For decades, we were told to avoid direct sun exposure as much as possible. But is that healthy? We were also conditioned to treat unprotected sun exposure as a sure path to skin cancer. But is this true?? This book seeks to answer those questions.
It is an essential, eye-opening read for anyone willing to challenge mainstream health dogmas. This book systematically dismantles entrenched anti-sun narratives by pulling directly from large-scale population studies and evolutionary biology. The writing here explains how daylight functions as a fundamental biological signal - one that directly impacts long-term mortality, metabolic health, and systemic disease prevention.
Author Rowan Jacobsen writes about science, nature, adventure, and technology for the world's top magazines and book publishers.
Rowan Jacobsen:
Jacobsen writes with a clear concise style here, so the book won't have any trouble holding the finicky reader's attention. It opens with a bang, and the pace stays lively throughout. He drops the quote above near the start of the book, and it continues:
The core argument of the thesis he lays out traces back to evolutionary biology: almost all life, and humans (specifically) evolved for billions of years under solar light exposure. Much of the energy that comes from the sun is actually biologically active light that affects many of our bodily systems and mechanics. We depend on that energy in ways that go far beyond basic Vitamin D synthesis.
He writes:
He also drops this quote, expanding further:
Some more highlights:
• Nitric Oxide & Blood Pressure: Exposure to UVA light mobilizes stored nitric oxide from skin tissue directly into the bloodstream, dilating blood vessels and lowering blood pressure independently of Vitamin D production.
• The Supplement Illusion: Oral Vitamin D pills fail to replicate the full biological impact of natural sunlight, which triggers complex hormonal, mitochondrial, and circadian signaling pathways across full-spectrum light wavelengths.
• Systemic Health Links: Sun deprivation is consistently linked to elevated risks for heart attack, stroke, diabetes, dementia, depression, Parkinson's, respiratory infections, and autoimmune conditions like MS and IBD.
• Economic & Institutional Bias: Sun safety messaging is heavily funded by industries selling protection, while public health institutions default to zero-risk models. The sun has no corporate lobby to promote its benefits.
Overall - I found the formatting of this one to be very well done as well. It is broken into well-defined chapters, and each chapter into different blurbs with relevant headers. Good job!
The chapters and topics covered here are:
Chapter 1: The Sunlight Paradox – Unpacking the medical establishment's refusal to acknowledge evolutionary UV-seeking behaviors.
Chapter 2: The Deprivation Epidemic – Mapping the direct connections between lack of light and modern chronic illnesses.
Chapter 3: The Mortality Data – Analyzing large-cohort studies (including the UK light study) isolating daylight as an independent health variable.
Chapter 4: Beyond Vitamin D – Examining the multi-systemic physiological mechanisms powered by full-spectrum light.
Chapter 5: The Economics of Fear – How dermatological guidelines prioritize complete avoidance and how product lobbying skews public perception.
Chapter 6: Nitric Oxide & Cardiovascular Health – How UVA light releases stored blood pressure-lowering compounds in the skin.
Chapter 7: Circadian Orchestration – The eyes, the suprachiasmatic nucleus, and how natural light cycles calibrate central hormonal clocks.
Chapter 8: The Red & Infrared Edge – How non-UV wavelengths penetrate deep tissue to stimulate cellular mitochondria and ATP production.
Chapter 9: The Dopamine Connection – Understanding the evolutionary neurochemistry behind UV-seeking habits and mood regulation.
Chapter 10: Skin Cancer Re-examined – Disentangling systemic burn risk from moderate, habituated solar exposure and baseline skin phenotypes.
Chapter 11: The Supplement Illusion – Why pill-based Vitamin D fails to replicate the systemic benefits of full-spectrum solar radiation.
Chapter 12: Biological Darkness – The physiological cost of indoor LED lighting and artificial light at night (ALAN).
Chapter 13: Quantum Biology of Light – Exploring emerging models of sub-cellular solar energy conversion.
Chapter 14: Practical Solar Protocols – Establishing safe exposure thresholds, latitude considerations, and seasonal adjustments.
Chapter 15: Reclaiming the Sun – A pragmatic framework for integrating natural daylight into modern life without burning..
********************
In Defense of Sunlight was a sharp, data-backed look into a fascinating subject matter. The writing, research, and overall presentation of this one were fantastic. I would easily recommend it to anyone interested.
In a cheecky homage to Michael Pollan's 2008 book In Defense of Food: An Eater's Manifesto, the author summarizes his thesis here:
"Get sun. Not too much. Go outside."
~ Nice.
5 stars, and a spot on my "favorites" shelf.
In Defense of Sunlight was an excellent look into the topic. For decades, we were told to avoid direct sun exposure as much as possible. But is that healthy? We were also conditioned to treat unprotected sun exposure as a sure path to skin cancer. But is this true?? This book seeks to answer those questions.
It is an essential, eye-opening read for anyone willing to challenge mainstream health dogmas. This book systematically dismantles entrenched anti-sun narratives by pulling directly from large-scale population studies and evolutionary biology. The writing here explains how daylight functions as a fundamental biological signal - one that directly impacts long-term mortality, metabolic health, and systemic disease prevention.
Author Rowan Jacobsen writes about science, nature, adventure, and technology for the world's top magazines and book publishers.
Rowan Jacobsen:
Jacobsen writes with a clear concise style here, so the book won't have any trouble holding the finicky reader's attention. It opens with a bang, and the pace stays lively throughout. He drops the quote above near the start of the book, and it continues:
"...But that wasn’t how the Harvard doctors saw it. They acknowledged that the discovery implied some “potential evolutionary benefit… that reinforces UV-seeking behavior,” but they didn’t want to touch that one with a ten-foot parasol. Instead, they focused on how this helped explain why it was so hard to break people of their sun habits. There was even talk of treating recreational tanning as a form of drug abuse."
The core argument of the thesis he lays out traces back to evolutionary biology: almost all life, and humans (specifically) evolved for billions of years under solar light exposure. Much of the energy that comes from the sun is actually biologically active light that affects many of our bodily systems and mechanics. We depend on that energy in ways that go far beyond basic Vitamin D synthesis.
He writes:
"In the world of journalism, I seemed to be the only one who was captivated by the news. And the more I dug around, the more astonished I got. The science consistently showed that people who received ample amounts of sun exposure lived longer, healthier lives than people who didn’t. Sun deprivation was linked to heart attack, stroke, diabetes, dementia, depression, Parkinson’s, myopia, respiratory infections, certain cancers, and autoimmune conditions such as multiple sclerosis and inflammatory bowel disease."
He also drops this quote, expanding further:
"In the case of the UK light study, even after adjusting for everything from exercise and diet to smoking and sleep duration, the sun getters were still 17 percent less likely to die. As the authors put it in their paper, “Personal day light exposure appears to be an independent predictor of mortality risk.”
Why? That’s what this book is about. The short answer is that the human body evolved in an environment of abundant sunlight, and we are designed to make use of that solar energy in various ingenious ways—ways that we are finally starting to understand.
If you’re wondering why you’ve never heard about any of this, well, join the club. After years of following the research and wondering why it wasn’t making its way into the public sphere, I’ve concluded that part of the problem is simply that the sun has no lobby. There are a lot of people whose job it is to tell you about the risks of too much sunlight, and a lot of companies hoping to sell you some product to protect yourself from it. In contrast, it’s nobody’s job to tell you about the good stuff..."
Some more highlights:
• Nitric Oxide & Blood Pressure: Exposure to UVA light mobilizes stored nitric oxide from skin tissue directly into the bloodstream, dilating blood vessels and lowering blood pressure independently of Vitamin D production.
• The Supplement Illusion: Oral Vitamin D pills fail to replicate the full biological impact of natural sunlight, which triggers complex hormonal, mitochondrial, and circadian signaling pathways across full-spectrum light wavelengths.
• Systemic Health Links: Sun deprivation is consistently linked to elevated risks for heart attack, stroke, diabetes, dementia, depression, Parkinson's, respiratory infections, and autoimmune conditions like MS and IBD.
• Economic & Institutional Bias: Sun safety messaging is heavily funded by industries selling protection, while public health institutions default to zero-risk models. The sun has no corporate lobby to promote its benefits.
Overall - I found the formatting of this one to be very well done as well. It is broken into well-defined chapters, and each chapter into different blurbs with relevant headers. Good job!
The chapters and topics covered here are:
Chapter 1: The Sunlight Paradox – Unpacking the medical establishment's refusal to acknowledge evolutionary UV-seeking behaviors.
Chapter 2: The Deprivation Epidemic – Mapping the direct connections between lack of light and modern chronic illnesses.
Chapter 3: The Mortality Data – Analyzing large-cohort studies (including the UK light study) isolating daylight as an independent health variable.
Chapter 4: Beyond Vitamin D – Examining the multi-systemic physiological mechanisms powered by full-spectrum light.
Chapter 5: The Economics of Fear – How dermatological guidelines prioritize complete avoidance and how product lobbying skews public perception.
Chapter 6: Nitric Oxide & Cardiovascular Health – How UVA light releases stored blood pressure-lowering compounds in the skin.
Chapter 7: Circadian Orchestration – The eyes, the suprachiasmatic nucleus, and how natural light cycles calibrate central hormonal clocks.
Chapter 8: The Red & Infrared Edge – How non-UV wavelengths penetrate deep tissue to stimulate cellular mitochondria and ATP production.
Chapter 9: The Dopamine Connection – Understanding the evolutionary neurochemistry behind UV-seeking habits and mood regulation.
Chapter 10: Skin Cancer Re-examined – Disentangling systemic burn risk from moderate, habituated solar exposure and baseline skin phenotypes.
Chapter 11: The Supplement Illusion – Why pill-based Vitamin D fails to replicate the systemic benefits of full-spectrum solar radiation.
Chapter 12: Biological Darkness – The physiological cost of indoor LED lighting and artificial light at night (ALAN).
Chapter 13: Quantum Biology of Light – Exploring emerging models of sub-cellular solar energy conversion.
Chapter 14: Practical Solar Protocols – Establishing safe exposure thresholds, latitude considerations, and seasonal adjustments.
Chapter 15: Reclaiming the Sun – A pragmatic framework for integrating natural daylight into modern life without burning..
********************
In Defense of Sunlight was a sharp, data-backed look into a fascinating subject matter. The writing, research, and overall presentation of this one were fantastic. I would easily recommend it to anyone interested.
In a cheecky homage to Michael Pollan's 2008 book In Defense of Food: An Eater's Manifesto, the author summarizes his thesis here:
"Get sun. Not too much. Go outside."
~ Nice.
5 stars, and a spot on my "favorites" shelf.
July 15, 2026
I highly recommend reading this book if you care about any aspect of your health.
July 23, 2026
Real solid
July 26, 2026
For the past half century, the prevalent message about sunlight is that it should be avoided whenever possible. Such stems from advices given to those with European ancestry who are now living in sunny countries such as most of the United States and Australia. According to author Rowan Jacobsen and Dr. Richard Weller (who wrote the book’s foreword), this one-size-fits-all approach has been a disservice to a substantial percentage of the population (i.e., those categorized as Types III through VI on the Fitzpatrick scale - pretty much most everyone who doesn’t have pale white skin). Mr. Jacobsen instead contends that insufficient sun exposure deprives us of numerous benefits that evolution came to confer, including: healthier immune function; increased metabolism and mitochondrial function; lower blood pressure; and better mood. In contrast, the book discusses numerous studies (controlled for age, diet, exercise, smoking, and socioeconomic status) demonstrating how sun deprivation is linked to heart attack, stroke, diabetes, depression, myopia, certain cancers, and autoimmune conditions.
Several mechanisms may be in play to explain this. When our skin is exposed to sunlight, it produces a molecule called proopiomelanocortin (POMC, pronounced pom-see), which is the precursor to essential compounds manufactured in the skin including melanin, cortisol (which contrary to popular belief is not bad in and of itself but rather a hormone which helps us handle stressors), and endorphins. UV rays also result in our body’s production of Vitamin D* as well as nitric oxide, the former of which is a critical hormone our bodies need to function properly (e.g., bone density, immune function, mood regulation), and the latter is important for mitochondria and proper blood vessel dilation. Further, approximately half of 50% of sunlight is infrared and near-infrared light, which is now trending vis-a-vis the study of photobiomodulation (light therapy to stimulate, heal, and regenerate cells).
A discussion about sun exposure must include skin cancer. Mr. Jacobsen certainly recognizes the connection but seeks to distinguish the different types. Squamous cell and basal cell carcinomas comprise about 98% of skin cancer cases, and are non-lethal as they affect the more superficial layers of the skin. Melanoma is the more dangerous form, and strangely those with the lowest survival rates seem to get the least sun exposure. This is possibly due to the potential protective qualities that Vitamin D has: a 2018 study found that those with Vitamin D deficiency were 25x more likely to contract melanoma. Also worth noting is that melanoma is far more prevalent in White people (28 per 100K) than Hispanics (5 per 100K) or Black and Asian people (1 per 100K). Unfortunately, science and medicine might have previously been incorrect in assuming that only UVB caused skin cancer, because what followed were sunscreens that blocked UVB (necessary for Vitamin D production) while letting UVA in, which can also be harmful. (Today’s sunscreens are now “full spectrum”.)
If Mr. Jacobsen is correct about the importance of sufficient sun exposure, it may take some time for the messaging to get through. The medical world is (perhaps rightfully) cautious about big changes or doing an about-face from its prior position. Regardless of the accuracy of this book, medical science is not a fixed body of knowledge - it continually evolves based on experimentation and accumulation of evidence. Consider how until quite recently we were advised to avoid eggs due to cholesterol fears, or to avoid fats in favor of carbohydrates.
The book closes with a simple prescription about sunlight: Get ample sunlight in lieu of artificial indoor lighting, especially in the morning, but never come close to burning.
*Almost an entire chapter is devoted to a discussing of studies and experiments showing how oral Vitamin D supplementation is ineffective in lieu of sunlight.
Several mechanisms may be in play to explain this. When our skin is exposed to sunlight, it produces a molecule called proopiomelanocortin (POMC, pronounced pom-see), which is the precursor to essential compounds manufactured in the skin including melanin, cortisol (which contrary to popular belief is not bad in and of itself but rather a hormone which helps us handle stressors), and endorphins. UV rays also result in our body’s production of Vitamin D* as well as nitric oxide, the former of which is a critical hormone our bodies need to function properly (e.g., bone density, immune function, mood regulation), and the latter is important for mitochondria and proper blood vessel dilation. Further, approximately half of 50% of sunlight is infrared and near-infrared light, which is now trending vis-a-vis the study of photobiomodulation (light therapy to stimulate, heal, and regenerate cells).
A discussion about sun exposure must include skin cancer. Mr. Jacobsen certainly recognizes the connection but seeks to distinguish the different types. Squamous cell and basal cell carcinomas comprise about 98% of skin cancer cases, and are non-lethal as they affect the more superficial layers of the skin. Melanoma is the more dangerous form, and strangely those with the lowest survival rates seem to get the least sun exposure. This is possibly due to the potential protective qualities that Vitamin D has: a 2018 study found that those with Vitamin D deficiency were 25x more likely to contract melanoma. Also worth noting is that melanoma is far more prevalent in White people (28 per 100K) than Hispanics (5 per 100K) or Black and Asian people (1 per 100K). Unfortunately, science and medicine might have previously been incorrect in assuming that only UVB caused skin cancer, because what followed were sunscreens that blocked UVB (necessary for Vitamin D production) while letting UVA in, which can also be harmful. (Today’s sunscreens are now “full spectrum”.)
If Mr. Jacobsen is correct about the importance of sufficient sun exposure, it may take some time for the messaging to get through. The medical world is (perhaps rightfully) cautious about big changes or doing an about-face from its prior position. Regardless of the accuracy of this book, medical science is not a fixed body of knowledge - it continually evolves based on experimentation and accumulation of evidence. Consider how until quite recently we were advised to avoid eggs due to cholesterol fears, or to avoid fats in favor of carbohydrates.
The book closes with a simple prescription about sunlight: Get ample sunlight in lieu of artificial indoor lighting, especially in the morning, but never come close to burning.
*Almost an entire chapter is devoted to a discussing of studies and experiments showing how oral Vitamin D supplementation is ineffective in lieu of sunlight.
August 28, 2026
"Most of [the energy that animates us] fell to Earth, embedded itself in a plant, and then found its way to you. But some of it found you directly. Either way, we are lumps of mud, animated by light, having a conscious experience of the universe. And we depend on constant infusions of light to keep the fun going."
The entire time I was reading this book, I--a person with a PhD in cancer biology--wanted to scream: YES!!!! FINALLY!!! It's frustrating how incredibly intuitive it was to me that the "sun is dangerous and nothing more" made no evolutionary sense. I've had arguments with other PhD students about the artificiality of the biological models that determined we must "never" expose our skin to sun, because the only outcome is cancer. I argued that a single layer of non-adaptive cells cannot be a stand-in for our own complex skin, which had to co-evolve with sun rays. I argued that sun screen is not needed for everyone all the time, and that skin tone matters. And I argued that using sun screen all the time does expose us to a class of chemicals that haven't been properly tested and vetted. I was told I was naive or stupid, and I ended up keeping it to myself that I occasionally partook in one of the "most dangerous carcinogens." The entire time I worried that our "no sun rays on skin without protection, ever" approach will be as damaging as our obsession with anti-bacterial soaps. And here it is--the time for reckoning.
Turns out, the scientists who urge for a NUANCED approach to sun exposure can no longer be silenced. Turns out that, as every evolutionary biologist could have guessed, we co-evolved with the sun and therefore we both can protect ourselves from it rather efficiently and need it to stay healthy and sane. Jacobsen explains calmly how we can overdo both sun exposure and sun protection. He clarifies the classes of skin cancer and their distinct risk factors (for melanoma it's sun burns in childhood). He doesn't use inflammatory language for long--he'll joke about the need to relax our old dogmas, without ever saying "everybody needs to stop using sun screen right now!" What we need is to understand who is at risk, and what are the healthy doses. He explains how our skin thickens and darkens in the sun, how DNA damage is stopped and DNA maintenance is increased with gradual careful sun exposure. He acknowledges the people at highest risk: those with very pale skin, living at low latitudes. But he also explains what radiation harm us and heal us. He explains why getting vitamin D from a pill is not a fix for lack of sun exposure. Because sun exposure gives us more than a simple hormone: it gives us a healthier metabolism, precursors for much needed neurotransmiters that affect our mood, and helps our immune system stay fit without overreacting. That's not even mentioning the way the sun affects our circadian rhythm.
In the end, the book is a warning that we cannot just pretend like our most common companion throughout evolution can be removed from our lives without some significant negative effects on our overall health. I did wish the book spent more time on classifying people based on their risk factors (including a mention of people who need to take draconian means to avoid sun: e.g. people with genetic maladies such as Porphyria, Li-Frameni syndrome, or people taking medication that enhances photosensitivity such as certain cancer drugs). But overall I thought this was a very well researched and well explained book about why we need to bring nuance, not just a high-SPF lotion, to the conversation about skin health. Remember, no organ exists in isolation. We are one giant consortium, and we contain multitudes.
The entire time I was reading this book, I--a person with a PhD in cancer biology--wanted to scream: YES!!!! FINALLY!!! It's frustrating how incredibly intuitive it was to me that the "sun is dangerous and nothing more" made no evolutionary sense. I've had arguments with other PhD students about the artificiality of the biological models that determined we must "never" expose our skin to sun, because the only outcome is cancer. I argued that a single layer of non-adaptive cells cannot be a stand-in for our own complex skin, which had to co-evolve with sun rays. I argued that sun screen is not needed for everyone all the time, and that skin tone matters. And I argued that using sun screen all the time does expose us to a class of chemicals that haven't been properly tested and vetted. I was told I was naive or stupid, and I ended up keeping it to myself that I occasionally partook in one of the "most dangerous carcinogens." The entire time I worried that our "no sun rays on skin without protection, ever" approach will be as damaging as our obsession with anti-bacterial soaps. And here it is--the time for reckoning.
Turns out, the scientists who urge for a NUANCED approach to sun exposure can no longer be silenced. Turns out that, as every evolutionary biologist could have guessed, we co-evolved with the sun and therefore we both can protect ourselves from it rather efficiently and need it to stay healthy and sane. Jacobsen explains calmly how we can overdo both sun exposure and sun protection. He clarifies the classes of skin cancer and their distinct risk factors (for melanoma it's sun burns in childhood). He doesn't use inflammatory language for long--he'll joke about the need to relax our old dogmas, without ever saying "everybody needs to stop using sun screen right now!" What we need is to understand who is at risk, and what are the healthy doses. He explains how our skin thickens and darkens in the sun, how DNA damage is stopped and DNA maintenance is increased with gradual careful sun exposure. He acknowledges the people at highest risk: those with very pale skin, living at low latitudes. But he also explains what radiation harm us and heal us. He explains why getting vitamin D from a pill is not a fix for lack of sun exposure. Because sun exposure gives us more than a simple hormone: it gives us a healthier metabolism, precursors for much needed neurotransmiters that affect our mood, and helps our immune system stay fit without overreacting. That's not even mentioning the way the sun affects our circadian rhythm.
In the end, the book is a warning that we cannot just pretend like our most common companion throughout evolution can be removed from our lives without some significant negative effects on our overall health. I did wish the book spent more time on classifying people based on their risk factors (including a mention of people who need to take draconian means to avoid sun: e.g. people with genetic maladies such as Porphyria, Li-Frameni syndrome, or people taking medication that enhances photosensitivity such as certain cancer drugs). But overall I thought this was a very well researched and well explained book about why we need to bring nuance, not just a high-SPF lotion, to the conversation about skin health. Remember, no organ exists in isolation. We are one giant consortium, and we contain multitudes.
Read
September 19, 2026This fascinating book details how societal and medical opinions of sunlight has changed in the last 200 years, digs into some details on what the three wavelengths of sunshine seem to actually do on and in our bodies (a lot of amazing stuff!), lays out the ways big companies have pushed and misrepresented the skin care and sunscreen products, and shares the author's personal experiences in trying a few things to overcome insomnia.
To summarize the book:
Avoid sunburn like the plague (but not by using sunscreen, if possible).
Get outside at dawn.
Get outside during the day.
Get outside at dusk.
Your body and brain will thank you.
To summarize the book:
Avoid sunburn like the plague (but not by using sunscreen, if possible).
Get outside at dawn.
Get outside during the day.
Get outside at dusk.
Your body and brain will thank you.
September 21, 2026
Incredibly interesting
August 10, 2026
I don't care about your airstream vacation dude. Give me the facts and the science behind it.
July 5, 2026
This was a VERY interesting book. Exposure to sunlight has been demonized. We are told that we should avoid direct sunlight wherever possible or face terrible medical consequences over time. This is a total overreaction but it’s very effective for marketing purposes. There is big money in selling sunscreens and clothing that blocks sunlight and since the sun does not have a marketing agency, the sun has become a villain.
The author is NOT suggesting that we expose ourselves to many hours of sunlight, avoid sunscreen, or avoid sun blocking clothing. But avoiding the sun, staying inside in artificial light all the time is not healthy. Exposure to sunlight in moderation, has some significant health benefits.
A couple of examples:
Sunlight hitting the skin produces Vitamin D, a hormone which regulates calcium in the body and is essential for strong bones and a number of basic biological processes. People with higher blood levels of Vitamin D have lower rates of diabetes, obesity, osteoporosis, heart attack, stroke, depression, cognitive impairment, autoimmune diseases, colorectal cancer and respiratory infections. Popping a Vitamin D pill is not even close to being as effective as exposure to sunlight.
The main molecules in the body that successfully absorb the near infrared light from the sun are found in the mitochondria, the site of cellular respiration which produces energy for the cell. Infrared light penetrates the skin (and clothing) and energizes our mitochondria. Every activity of our bodies requires energy, including but not limited to motion, cognition and healing. If the mitochondria wear out, our bodies wear out. Infrared light comprises 53% of the solar spectrum, more than all other visible light combined. The LED lights that are the norm in most office buildings have much less infrared light than sunlight. Photobiomodulation (also called red-light therapy) is used in thousands of clinics around the world to treat wound healing, hair loss, and cognitive disorders such as Parkinson’s disease. Dentists use red light therapy (red laser) on our gums during some dental procedures because gums heal faster when exposed to red light. Anytime we are outside in daylight, photons of infrared light are pouring into us, energizing our mitochondria, even through our clothing. Years ago, that used to happen a lot every day but now that we spend most of our time indoors, it happens a LOT less which is not good.
There is SO much interesting science in this book that made So much sense. Again, the author is not saying to sit out and sunbathe all day. The author is an award winning science writer whose work has appeared in MIT Technology Review, The Best American Science and Nature Writing and many others.
His advice: Get Sun. Not too much. Go outside.
The author is NOT suggesting that we expose ourselves to many hours of sunlight, avoid sunscreen, or avoid sun blocking clothing. But avoiding the sun, staying inside in artificial light all the time is not healthy. Exposure to sunlight in moderation, has some significant health benefits.
A couple of examples:
Sunlight hitting the skin produces Vitamin D, a hormone which regulates calcium in the body and is essential for strong bones and a number of basic biological processes. People with higher blood levels of Vitamin D have lower rates of diabetes, obesity, osteoporosis, heart attack, stroke, depression, cognitive impairment, autoimmune diseases, colorectal cancer and respiratory infections. Popping a Vitamin D pill is not even close to being as effective as exposure to sunlight.
The main molecules in the body that successfully absorb the near infrared light from the sun are found in the mitochondria, the site of cellular respiration which produces energy for the cell. Infrared light penetrates the skin (and clothing) and energizes our mitochondria. Every activity of our bodies requires energy, including but not limited to motion, cognition and healing. If the mitochondria wear out, our bodies wear out. Infrared light comprises 53% of the solar spectrum, more than all other visible light combined. The LED lights that are the norm in most office buildings have much less infrared light than sunlight. Photobiomodulation (also called red-light therapy) is used in thousands of clinics around the world to treat wound healing, hair loss, and cognitive disorders such as Parkinson’s disease. Dentists use red light therapy (red laser) on our gums during some dental procedures because gums heal faster when exposed to red light. Anytime we are outside in daylight, photons of infrared light are pouring into us, energizing our mitochondria, even through our clothing. Years ago, that used to happen a lot every day but now that we spend most of our time indoors, it happens a LOT less which is not good.
There is SO much interesting science in this book that made So much sense. Again, the author is not saying to sit out and sunbathe all day. The author is an award winning science writer whose work has appeared in MIT Technology Review, The Best American Science and Nature Writing and many others.
His advice: Get Sun. Not too much. Go outside.
Review of advance copy received from Netgalley
Short Yet Thoroughly Documented Clarion Call Inspired By Pollan's In Defense Of Food. In this text, Jacobsen explicitly sets out to do for sunlight what Michael Pollan once did for "real food" several years ago... and largely nails it. The writing here is engaging and explains the science at a level that most will be able to understand it yet doesn't shy away from the more complex areas of the science either. At just under 300 pages with just over a quarter of even that being documentation, this is an easy one day read for many people... and yet will also be one that many readers will want to sip and savor and perhaps spread out over a much longer reading period.
Perhaps, even, via reading it for a few minutes per day as the sun rises or sets... which is a particular period Jacobsen shows does quite a bit for the human body.
In all honesty, I read this book when I did - days before the dreaded "Spring Forward" of "Daylight Saving Time" - hoping for a much stronger anti-DST argument here, which isn't as present as I had hoped... but that actually points to the actual strengths of the text, as Jacobsen is more concerned that you get outside at all than *when* you get outside, though he does indeed go into detail about what the sun's light at different times of the day can do for you and does in fact make at least some case for the earlier sunrises of so-called "Standard" time, while also pointing out the science of living on the eastern vs western edges of a time zone, among many other topics.
Overall a very thorough text covering all aspects of the science of the interaction of the sun and the human body, this is absolutely one book everyone needs to read and make their own calls about... and perhaps even recommend it to your medical providers. I know I'll be recommending my own docs read this.
Very much recommended.
Perhaps, even, via reading it for a few minutes per day as the sun rises or sets... which is a particular period Jacobsen shows does quite a bit for the human body.
In all honesty, I read this book when I did - days before the dreaded "Spring Forward" of "Daylight Saving Time" - hoping for a much stronger anti-DST argument here, which isn't as present as I had hoped... but that actually points to the actual strengths of the text, as Jacobsen is more concerned that you get outside at all than *when* you get outside, though he does indeed go into detail about what the sun's light at different times of the day can do for you and does in fact make at least some case for the earlier sunrises of so-called "Standard" time, while also pointing out the science of living on the eastern vs western edges of a time zone, among many other topics.
Overall a very thorough text covering all aspects of the science of the interaction of the sun and the human body, this is absolutely one book everyone needs to read and make their own calls about... and perhaps even recommend it to your medical providers. I know I'll be recommending my own docs read this.
Very much recommended.
Review of advance copy received from Netgalley
"In Defense of Sunlight" discussed scientific studies on the benefits and dangers of sunlight to human health using a historical framework. In the 1800s, scientists realized that lack of sunlight in badly polluted cities was causing rickets in children. Doctors started treating diseases like tuberculosis with sunlight, and the recommendations moved toward nude sunbathing for your health. Scientists discovered vitamin D. So, of course, people made vitamin D pills and UV lamps as health products but discovered neither quite lived up to hopes (though a narrow wavelength UV light can be used to treat multiple sclerosis!).
The author covered the skin cancer scare that lead to the current recommendations as well as the history of sunscreen, its variable effectiveness at blocking UV, and research into if it really does stop skin cancer. He also showed why the actual science is much more nuanced than 'everyone should always wear sunscreen.' You can get many health benefits from the sun while most sun-exposure cancers won't kill you, so informed sun exposure (especially for darker-skinned people) is desirable. After covering recent scientific studies on why getting sun on your skin provides various health benefits, he covered the latest science-based recommendations for how much sun your skin type should get and when is the best times to get it.
Though there is a lot of good scientific information in this book (thank you!), it's an easy read and the science is explained in terms a high schooler could understand. I knew I enjoyed the joint-deep warmth of the sun, and now I better understand why I'm drawn to sun exposure, especially in the morning. It helps your body in a multitude of ways. Overall, I'd highly recommend this informative and interesting book.
I received a free ebook review copy of this book from the publisher through NetGalley.
The author covered the skin cancer scare that lead to the current recommendations as well as the history of sunscreen, its variable effectiveness at blocking UV, and research into if it really does stop skin cancer. He also showed why the actual science is much more nuanced than 'everyone should always wear sunscreen.' You can get many health benefits from the sun while most sun-exposure cancers won't kill you, so informed sun exposure (especially for darker-skinned people) is desirable. After covering recent scientific studies on why getting sun on your skin provides various health benefits, he covered the latest science-based recommendations for how much sun your skin type should get and when is the best times to get it.
Though there is a lot of good scientific information in this book (thank you!), it's an easy read and the science is explained in terms a high schooler could understand. I knew I enjoyed the joint-deep warmth of the sun, and now I better understand why I'm drawn to sun exposure, especially in the morning. It helps your body in a multitude of ways. Overall, I'd highly recommend this informative and interesting book.
I received a free ebook review copy of this book from the publisher through NetGalley.
July 22, 2026
This is a fascinating book about the science of exposure to the sun. It is filled with scientific facts and examples of how exposure to the sun affects us. For quite some time, it has been drummed into us that exposure to the sun is bad, it will give us skin cancer, and we need to lather on tons of sunscreen multiple times a day, every day to avoid catastrophic results such as skin cancer. The author makes the argument that this is a total overreaction. It is basically a marketing ploy by the makers of sunscreen in order to make money. He says that while we should not bake in the sun for hours and risk getting sunburn, which is definitely not a good thing, exposure to sunlight can be very beneficial in many ways. Exposure to sunlight produces vitamin D which has many benefits. People with higher blood levels of Vitamin D have lower rates of diabetes, obesity, osteoporosis, heart attack, stroke, depression, cognitive impairment, autoimmune diseases, colorectal cancer and respiratory infections. And taking a Vitamin D pill is not even close to being as effective as exposure to sunlight. And the need for using sunscreen varies greatly depending on your skin type. Those with very fair skin have a greater need for using it than those with darker skin. The key is to avoid getting sunburn.
There is SO much interesting information in this book. The author is not saying we should sit out and sunbathe all day long, but we should not avoid sun exposure all together. His advice is to get some sun, not too much, go outside. I highly recommend this book.
There is SO much interesting information in this book. The author is not saying we should sit out and sunbathe all day long, but we should not avoid sun exposure all together. His advice is to get some sun, not too much, go outside. I highly recommend this book.
July 28, 2026
Rowan Jacobson’s book, “In Defense of Sunlight: The Surprising Science of Sun Exposure,” is a great resource that dives deep into the evidence and numerous studies about how much sun we need. It breaks down complex scientific terms and shows how sun exposure is essential for our well-being. From his research, Jacobson has found that getting a little bit of sun in moderation isn’t something to worry about. In fact, it’s something our bodies really need. The book points out the serious health problems that can come from not getting enough sunlight, like higher chances of high blood pressure, depression, heart disease, diabetes, dementia, and multiple sclerosis, along with trouble sleeping because of disruption of sleep patterns due to an off-kilter internal clock caused by inadequate sunlight.
Jacobson’s extensive years of reporting and research have provided him with access to numerous significant studies that are often overlooked due to potential biases in the sun care industry. Jacobson challenges the idea that we should always hide from the sun. Instead, he shares a growing number of medical studies that show that getting the right amount of sun can be really good for our health. He stresses the importance of knowing the health risks of avoiding the sun completely. Jacobson makes it clear that he’s not saying we should worship the sun. He gives us a simple seven-word tip: “Get sun, not too much, go outside.” Simply a fascinating read!
Jacobson’s extensive years of reporting and research have provided him with access to numerous significant studies that are often overlooked due to potential biases in the sun care industry. Jacobson challenges the idea that we should always hide from the sun. Instead, he shares a growing number of medical studies that show that getting the right amount of sun can be really good for our health. He stresses the importance of knowing the health risks of avoiding the sun completely. Jacobson makes it clear that he’s not saying we should worship the sun. He gives us a simple seven-word tip: “Get sun, not too much, go outside.” Simply a fascinating read!
September 14, 2026
This is one of the latest books on sunlight and health, alongside Torkil Færø’s The Sun Cure. It is informative and rewarding, exploring recent research into sunlight and sun exposure. Like much of the research that has come before it, the book offers hope and encouragement both to those who long for more sunshine and to those who have been taught to regard the sun as dangerous. Its message is clear: the sun is not something we need to fear.
Rowan Jacobsen writes in a style reminiscent of Michael Pollan, although Jacobsen engages more directly with the science. He even offers his own version of Pollan’s famous advice, “Eat food. Not too much. Mostly plants”: “Get sun. Not too much. Go outside.”
It is also fascinating to read about the author’s journey from insomnia to sound, restorative sleep. He learned to use sunlight and artificial light in ways that helped synchronize his body’s circadian rhythm.
I love the sun, and I find books about sunlight especially interesting because many of them challenge the conventional paradigm—a paradigm that often encourages us to fear the sun rather than embrace it. Read this book and be inspired. One new thing I learned was that infrared light, unlike UVB radiation, can penetrate clothing to some extent. This suggests that we may receive some of its potential health benefits simply by spending time outdoors in daylight.
A very good book!
Rowan Jacobsen writes in a style reminiscent of Michael Pollan, although Jacobsen engages more directly with the science. He even offers his own version of Pollan’s famous advice, “Eat food. Not too much. Mostly plants”: “Get sun. Not too much. Go outside.”
It is also fascinating to read about the author’s journey from insomnia to sound, restorative sleep. He learned to use sunlight and artificial light in ways that helped synchronize his body’s circadian rhythm.
I love the sun, and I find books about sunlight especially interesting because many of them challenge the conventional paradigm—a paradigm that often encourages us to fear the sun rather than embrace it. Read this book and be inspired. One new thing I learned was that infrared light, unlike UVB radiation, can penetrate clothing to some extent. This suggests that we may receive some of its potential health benefits simply by spending time outdoors in daylight.
A very good book!
Review of advance copy received from Netgalley
In Defense of Sunlight is a fascinating and eye-opening book about something most of us take for granted: sunlight. Instead of just warning about sun exposure, the author looks at the many ways sunlight supports our health and well-being.
What I loved most about this book is how clearly it explains the science. The author breaks down complex topics in a way that is easy to understand while still feeling well researched and thoughtful. It explores how sunlight affects sleep, mood, and overall health, and it really made me rethink how much time I spend outside during the day.
The book is packed with information but still very readable. It’s the kind of book you could read quickly, but it’s also one that makes you pause and reflect on small daily habits. By the end, I found myself appreciating sunlight in a whole new way.
Overall, this was an engaging and informative read that makes a strong case for the importance of getting outside and connecting with natural light.
Thank you to NetGalley and the publisher for the ARC in exchange for my honest review.
What I loved most about this book is how clearly it explains the science. The author breaks down complex topics in a way that is easy to understand while still feeling well researched and thoughtful. It explores how sunlight affects sleep, mood, and overall health, and it really made me rethink how much time I spend outside during the day.
The book is packed with information but still very readable. It’s the kind of book you could read quickly, but it’s also one that makes you pause and reflect on small daily habits. By the end, I found myself appreciating sunlight in a whole new way.
Overall, this was an engaging and informative read that makes a strong case for the importance of getting outside and connecting with natural light.
Thank you to NetGalley and the publisher for the ARC in exchange for my honest review.
July 25, 2026
I give it 5 stars, because this is a book that had to be written. Jacobsen is starting a debate we need to have.
How did humans evolve over thousands of years thriving in the sunlight, and suddenly we have to stay inside to survive? We aren’t getting the complete picture.
Jacobsen is a journalist, not a scientist. Before this debate is over, I suspect several items of evidence he offers will be successfully challenged. And I cringed as I read parts where he praised some of the shaky medical practices used to treat tuberculosis a hundred years ago. But I believe he will prevail on his main point. The current recommendations for restricted access to sunlight make little sense for people with darker skin. For those with lighter skin, the entire medical profession has to be honest about the dangers of restricted sunlight, as well as the benefits when it comes to skin cancer.
This short book is a must read. Many vested interests will hate it and attack it. That’s fine. Let’s have the debate, and hope it’s an honest one.
How did humans evolve over thousands of years thriving in the sunlight, and suddenly we have to stay inside to survive? We aren’t getting the complete picture.
Jacobsen is a journalist, not a scientist. Before this debate is over, I suspect several items of evidence he offers will be successfully challenged. And I cringed as I read parts where he praised some of the shaky medical practices used to treat tuberculosis a hundred years ago. But I believe he will prevail on his main point. The current recommendations for restricted access to sunlight make little sense for people with darker skin. For those with lighter skin, the entire medical profession has to be honest about the dangers of restricted sunlight, as well as the benefits when it comes to skin cancer.
This short book is a must read. Many vested interests will hate it and attack it. That’s fine. Let’s have the debate, and hope it’s an honest one.
September 11, 2026
Great summary of the latest, surprising science about the role of the sun in human health. Evidence strongly suggests that the modern habit of spending most of our time indoors in artificial lighting is a root cause of myriad health problems, and our fear of skin cancers, while still valid, has been greatly exaggerated and may actually produce net negative public health outcomes. We evolved under the sun; it's not an alien cosmic killer.
I spend a lot of time in the South Carolina sun, and this book offers evidence and practical suggestions for modified approaches for how to garner the physiological and cognitive benefits of the solar spectrum of visible and near infrared light while avoiding hazardous overexposure to UVA and UVB wavelengths. Gone are the days of slathering on SFP 30-50 every time I go outside. A more nuanced approach centered on the mantra "get outside, don't burn" can address a mind-blowing array of health challenges.
I spend a lot of time in the South Carolina sun, and this book offers evidence and practical suggestions for modified approaches for how to garner the physiological and cognitive benefits of the solar spectrum of visible and near infrared light while avoiding hazardous overexposure to UVA and UVB wavelengths. Gone are the days of slathering on SFP 30-50 every time I go outside. A more nuanced approach centered on the mantra "get outside, don't burn" can address a mind-blowing array of health challenges.
June 18, 2026
A quiet revolution is challenging the long-held “zero-sun” policy, revealing that moderate sun exposure offers significant health benefits. This book presents scientific evidence that modest sun exposure is crucial for overall well-being and to avoid harm.
This engaging and easy-to-read book is a wonderful corrective to the common understanding about sunscreen use. I was shocked to learn that sunscreen is not proven to reduce melanoma—only the less deadly forms of skin cancer.
As a fair-skinned person living in the tropics, I won’t change my behavior regarding sunscreen use as a result of reading this book—though I will make more of an effort to get sun every day. Darker-skinned people, however, might want to discuss their personal sunscreen regimen with their dermatologist.
Thanks, NetGalley, for the ARC I received. This is my honest and voluntary review.
This engaging and easy-to-read book is a wonderful corrective to the common understanding about sunscreen use. I was shocked to learn that sunscreen is not proven to reduce melanoma—only the less deadly forms of skin cancer.
As a fair-skinned person living in the tropics, I won’t change my behavior regarding sunscreen use as a result of reading this book—though I will make more of an effort to get sun every day. Darker-skinned people, however, might want to discuss their personal sunscreen regimen with their dermatologist.
Thanks, NetGalley, for the ARC I received. This is my honest and voluntary review.
July 8, 2026
Enlightening. No pun intended.
No, but seriously, Rowan Jacobsen’s In Defense of Sunlight is a sharp, well written challenge to decades of standard public health advice.
Jacobsen argues that our collective "zero-sun policy" has created a massive, unseen health crisis, moving far beyond Vitamin D to show how moderate solar exposure lowers blood pressure, regulates sleep, and combats depression.
Crucially, the book rejects lazy "one-size-fits-all" messaging, explaining how blanket anti-sun warnings accidentally harm people with darker skin tones, who face minimal melanoma risks but suffer heavily from sunlight deprivation.
Written with deep scientific literacy and wit, this eye-opening book replaces fear-mongering with a brilliant seven-word rule of thumb:
"Get sun. Not too much. Go outside."
No, but seriously, Rowan Jacobsen’s In Defense of Sunlight is a sharp, well written challenge to decades of standard public health advice.
Jacobsen argues that our collective "zero-sun policy" has created a massive, unseen health crisis, moving far beyond Vitamin D to show how moderate solar exposure lowers blood pressure, regulates sleep, and combats depression.
Crucially, the book rejects lazy "one-size-fits-all" messaging, explaining how blanket anti-sun warnings accidentally harm people with darker skin tones, who face minimal melanoma risks but suffer heavily from sunlight deprivation.
Written with deep scientific literacy and wit, this eye-opening book replaces fear-mongering with a brilliant seven-word rule of thumb:
"Get sun. Not too much. Go outside."
August 5, 2026
⭐️3.5 stars on Fable.
As someone who avoids sunlight and turned their bedroom into a blacked out dungeon, I found this illuminating. I’ve known that I should be getting more sunlight, but I was ignorant to all of the benefits it has. Med school really indoctrinates you with the “less sun, more sunscreen, here’s your vitamin D” approach given how prevalent skin cancer is in the US. What I liked about this book, though I think it was at times a bit repetitive with the point, is that its main claim is modern humans don’t get nearly enough sunlight and could benefit from moderate amounts of sun exposure with sunscreen (preferably in the morning, not afternoon). That sounds reasonable to me and the studies cited were pretty interesting. Will be enjoying my morning coffee in the sun from now on. Solid read.
As someone who avoids sunlight and turned their bedroom into a blacked out dungeon, I found this illuminating. I’ve known that I should be getting more sunlight, but I was ignorant to all of the benefits it has. Med school really indoctrinates you with the “less sun, more sunscreen, here’s your vitamin D” approach given how prevalent skin cancer is in the US. What I liked about this book, though I think it was at times a bit repetitive with the point, is that its main claim is modern humans don’t get nearly enough sunlight and could benefit from moderate amounts of sun exposure with sunscreen (preferably in the morning, not afternoon). That sounds reasonable to me and the studies cited were pretty interesting. Will be enjoying my morning coffee in the sun from now on. Solid read.
Review of advance copy received from Netgalley
Absolutely fascinating! This book delivers the nitty gritty science in a way that is readable, accessible, and interesting. Everyone should read this, especially since it takes public policy and health so long to adapt to new evidence and discoveries.
The key take aways: the sun is not something to be feared, but an essential source of health and vitality. We need a more nuanced approach than “avoid the sun and wear sunscreen every day.” Depending on skin tone, location, and life circumstances, your sun exposure might need some radical changes in order to gain all the benefits to your heart, metabolism, and more.
I would highly recommend this book to anyone interested in optimizing their health.
The key take aways: the sun is not something to be feared, but an essential source of health and vitality. We need a more nuanced approach than “avoid the sun and wear sunscreen every day.” Depending on skin tone, location, and life circumstances, your sun exposure might need some radical changes in order to gain all the benefits to your heart, metabolism, and more.
I would highly recommend this book to anyone interested in optimizing their health.
August 24, 2026
Yeaaaaa! I can still enjoy the sun. This is a well written, informative book on the tremendous benefits of sun exposure. He also addresses the risks of sun exposure, highlighting where we still need to be careful and debunking some of the claims that have been overly hyped. All of this is done in a very scientific manner, underscoring the issues with certain types of research (ie. observational studies) that frequently must be used in this area of study. Here are the benefits: Lowers BP and better CV health,
Improve mood and reduce stress, Healthier immune function and reduced chronic inflammation, Increased metabolism and mitochondrial function, Better sleep, Enhanced energy alertness and cognition. And here's his overall mantra: Get sun, not too much, go outside.
Improve mood and reduce stress, Healthier immune function and reduced chronic inflammation, Increased metabolism and mitochondrial function, Better sleep, Enhanced energy alertness and cognition. And here's his overall mantra: Get sun, not too much, go outside.
September 8, 2026
The sun was a part of the reason I had achieved full remission from a severe form of psoriasis. And ever since I used that crude treatment that involved intermittent sun exposure (among other things) I was just awe-struck by its potential for healing.
So when I heard of this book, I had to read it. I know the American Academy of Dermatology has clearly marked UV exposure from the sun as a carcinogen. And as a result, many people choose to protect themselves against the sun at all times. But this book chronicles recent studies that make the convo around sun and health far more nuanced.
Highly recommend.
So when I heard of this book, I had to read it. I know the American Academy of Dermatology has clearly marked UV exposure from the sun as a carcinogen. And as a result, many people choose to protect themselves against the sun at all times. But this book chronicles recent studies that make the convo around sun and health far more nuanced.
Highly recommend.
September 26, 2026
This was such an interesting and well researched book. It will change the way you look at the sun and sun exposure! Sun exposure plays such an important role in our lives!
The sections about sun exposure, sunscreen, sunburns, and melanoma were particularly interesting. Childhood sunburns are bad and I’m personally doing everything to prevent my son from getting them, while still allowing him to be outside as much as possible! It’s all very thought provoking!
If you enjoy science, especially science related something that affects everyday life, then I highly recommend picking up a copy of this book!
The sections about sun exposure, sunscreen, sunburns, and melanoma were particularly interesting. Childhood sunburns are bad and I’m personally doing everything to prevent my son from getting them, while still allowing him to be outside as much as possible! It’s all very thought provoking!
If you enjoy science, especially science related something that affects everyday life, then I highly recommend picking up a copy of this book!
July 3, 2026
So there’s been some stirrings about the benefits of sun (versus all that we’ve heard since the 80s about using sunscreen)...so I was intrigued to read this book diving deeper into the concept with some scientific data.
It is a short read, and I’d recommend the audio and print if you are interested in reading more about the topic.
It does spend quite a bit of time walking you the reader through the timeline of “sunscreen” and “sun benefits”....so that might be helpful (or redundant if you already know it).
Jacobsen does dwell on the idea of sleep- including a dark sky sleep study he does- I found that interesting!
I would like to still continue reading more on this consent.
It is a short read, and I’d recommend the audio and print if you are interested in reading more about the topic.
It does spend quite a bit of time walking you the reader through the timeline of “sunscreen” and “sun benefits”....so that might be helpful (or redundant if you already know it).
Jacobsen does dwell on the idea of sleep- including a dark sky sleep study he does- I found that interesting!
I would like to still continue reading more on this consent.
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