It's completely pointless for the general public, the media, or anyone else to take any particular advice or truth from any single medical study. Even if it's a good study, and you know how to evaluate if its good, even if it's highly plausible and has a mechanism of action it's almost never the case that a single study will be likely to make a strong enough case to jump to a conclusion or even consider a conclusion highly likely.
What results? "People who go outside live longer"? "People who can afford to leave Sweden to go sunbathing live longer"? I agree with the point about single studies, but even if you have multiple studies they still have to be good studies that answer the actual question you had (which in this case is probably "should I wear a hat and sunscreen?").
No, I agree that touching grass is associated with being good for you, I just disagree that higher levels of UV exposure are what makes it good for you. Touching grass has been a confounding variable in every association study I've read which claims to be about sun exposure, and the phrase "sun exposure" is ambiguous enough that it's often misinterpreted as "UV exposure".
This is a glib and dismissive response that tells me nothing. It's about as helpful as "do your own research". Mate, I have done my own research, everything I can find is either a vague association study or has a tiny underpowered treatment group and reeks of publication bias.
If Google Scholar is providing you with papers (other than this one, which is about rich Swedish people/Swedish people who go outside more) that prove your hypothesis (which you haven't even stated, just hinted at) then you should either link to those papers or not reply.
I was just replying to the lazy untrue grandparent comment about this being a single study. I'm glad I don't need to do your research for you.
As for the discussion, there are multiple lines of evidence pointing to the fact that sunlight does in fact reduce mortality. First, this study controls for exercise, and also found that use of tanning beds reduces all cause mortality, so overall it's a pretty good study. We also know that vitamin D status is negatively correlated with mortality. We also know that nitric oxide reduces blood pressure, and is released from the skin by sunlight.
Seems kind of like a no brainer given what we know about skin cancer, but I'm kind of surprised if you control for that if it had any other great "opportunity" to increase your lifespan when you control for obvious ones like exercise, diet, and controlling stress. I'm not a big outside lover, but I do take a daily walk to hopefully get bit of vitamin D from it. I mostly exercise indoors and my hobbies are almost all indoors.
I’d say not at all, this is pretty common advice, but maybe depends on what you mean by unorthodox, exactly. The advice is fairly good (and routine) for studies and papers from any discipline. All kinds of things can cause a single paper, single set of authors, single methodology, single dataset, etc., to come to misleading conclusions. The study can even be accurate in their measurements but not representative in subtle ways that are important. Before using someone’s results or making decisions based on it, it’s good to wait for confirmation from someone else, and even more so for a meta analysis of multiple publications.
No, the orthodox advice is to get your information from your doctor or, if he's a doofus, directly from the local professional association (e.g. American Heart Association), who do the work of reviewing and weighing the literature for you.
Unorthodox but probably not wrong. Replication is key. They might have overlooked something obvious or unexpected, or they might have faked data, and we would never know without an attempted replication.
Before anyone gets too excited about another opportunity to say the line about correlation:
> We acknowledge several major limitations of this study. First, it is not possible to differentiate between active sun exposure habits and a healthy lifestyle, and secondly, the results are of an observational nature; therefore, a causal link cannot be proven.
Though a single study doesn’t create a causal link anyways. When they write that, it contributes to the meme that a study can reveal causation rather than march the convergence of evidence towards causal inferences.
All studies investigate correlation and that’s okay. Though this discussion overshadows that study’s actual problems.
I wager it’s only on HN because its title is an excuse for everyone to hone their hobby horse opinion on sun exposure.
I mean, perhaps we don't need to say it because they say it explicitly.
Which makes me think that the title about "avoidance of sun exposure" is misleading, even if not deliberately so. "Avoidance" in the general lexicon usually means conscious choices to deliberately not expose yourself to something. Is someone who is, say, obese and bedridden "avoiding" sun exposure?
Sure. This is in every single study using surveys or statistics and yet everyone thinks the paper is making a casual argument. The paper itself actually does do that. So the whole limitations part is just ass covering for the fact that the authors are lying.
Why call it anything else. I mean it's like me writing a long paper proving that thermodynamics is flawed and then ending the paper with some acknowledgement that one of the key arguments has a logical flaw which renders the whole proof incorrect. So then the whole paper is worthless.
They do adjust the results for certain lifestyle factors, in particular exercise and smoking. They are just pointing out that they can't correct for all lifestyle factors.
I've read in "Lies My Doctor Told Me" by the MD Ken Berry that there isn't a single paper that shows that sun exposure is bad.
In particular the current consensus is that Vitamin D is essential to health and so this is considering that sun is avoided but replaced by pills, as the protective role of vitamin D is well-proven. But there are many other health benefits that are triggered by sun exposure (the skin metabolism activates and it goes down to influence gene expression).
So I've looked a few articles (at least 7, including some reviewing existing research), and sure enough there wasn't a single paper that actually showing that sun exposure is bad. They all relied on showing on something related to sunlight, most of the time that suntanning with artificial UV beds is really bad. But there it lacks a convincing argument that this transfers to 'the real product', as this is the equivalent of saying that carrots are good/bad for people based on some people ingesting large quantities of carotene in pills. And we know from diet that these kinds of arguments do break down when extrapolating only part of one molecule to a whole, natural product (eggs are a famous example).
If somebody has done more research on this please elaborate, I haven't spent too much time because the research seemed in all cases fairly low quality (questionnaires?) and a lot contained confusing arguments (it's not always clear how dark-skinned the individuals are, or how removed from their natural habitat they are, like some Swedish in Australia or Kenyan in the UK, although some do make an effort in that regard).
Well, the conclusion of this study appears to be that it doesn't. Or rather, if I'm reading this right, they're saying the increase in deaths due to skin cancer is just a statistical artifact: more women in the sun exposure group died of skin cancer, not necessarily because the sun caused the skin cancer, but because the women who stayed indoors died of cardiovascular disease instead.
My favorite quip regarding this statistical effect is the observation that the cyanide diet is very effective at reducing deaths due to cardiovascular disease (cyanide kills you much faster, so winds up hogging all the credit).
To avoid the mistake, insist on seeing all cause mortality numbers.
except the reality for the vast number of people isn't about needing to moderate, it's about getting outside period, instead of glued to their devices inside
you can look at the epidemic of myopia as a related indicator that kids especially are not outside enough
so this whole safetyism nagging about melanoma is ridiculous when they can just go to regular dermatologist screenings and avoid sunburns
Sunlight filtered by a window is very different from natural sunlight.
There are two main reasons this is a very poor indicator for sunlight exposure:
- since UV that is filtered out by glass will cause good metabolic reactions, this example takes out the positive of sunlight
- sunlight has a natural "stop it" mechanism. Feeling that you are getting a sunburn would naturally cause you to avoid sunlight, creating therefore a macro regulation mechanism. This is absent from light behind a glass.
So this is showing the exact point I was making that people take something that is not natural sunlight and falsely equate the two.
- sunlight has a natural "stop it" mechanism. Feeling that you are getting a sunburn would naturally cause you to avoid sunlight, creating therefore a macro regulation mechanism. This is absent from light behind a glass.
You seriously suggest the we have mechanism to prevent sunburns? Like the thing people get all the time while at the beach?
It must be very inefficient mechanism since all I remember is that when I notice it i am already sun burned.
So you suggest that even after getting sunburns, people do not avoid sunburns, and are thus at a much lower level of cognitive function than most of the animal kingdom?
You haven't replied to any of the points I'm making, all while making gross scientific errors such as equating glass filtered sunlight to sunlight, so I won't interact any further.
> Four predetermined questions were posed regarding sun exposure: (i) How often do you sunbathe during the summertime? (never, 1−14 times, 15−30 times, >30 times); (ii) Do you sunbathe during the winter, such as on vacation to the mountains? (no, 1−3 days, 4−10 days, >10 days); (iii) Do you use tanning beds? (never, 1−3 times per year, 4−10 times per year, >10 times per year); and (iv) Do you go abroad on vacation to swim and sunbathe? (never, once every 1–2 years, once a year, two or more times per year). The four questions were dichotomized into yes/no in the analysis (i.e. sometimes versus no or never). We created a four-score variable as a measure of sun exposure depending on the number of ‘yes’ responses to the above questions on a scale from 0 (avoid sun exposure: reference) to 4 (greatest sun exposure). Sun exposure habits were categorized into three groups: zero ‘yes’ responses (avoidance of sun exposure; the main study group); ‘yes’ responses to one or two questions (moderate exposure); and ‘yes’ responses to three or four questions (greatest exposure).
Of note, the surveys are of Swedish women and were conducted in Swedish. There could be some translation nuance for the word "sunbathe" which doesn't map well to English, or other cultural differences to explain the "but no one I know actually sunbathes..." thought that I immediately jump to.
> other cultural differences to explain the "but no one I know actually sunbathes..." thought that I immediately jump to.
Having grown up in Denmark that thought sounds odd to me. People really don’t sunbathe where you’re from?
What do people do on the beach, or in the park all summer? Not to mention at the tanning salon, before going on vacation to sunbathe at the beach (can’t look pale when sunbathing!)
Just to affirm the parent post, yes, sunbathing has also been rather rare everywhere I lived:
- South Dakota (USA)
- Arizona (USA)
- San Diego California (USA)
- Ankara (Turkey/Türkiye)
I saw evidence that people sunbathed in some of these locations (it’s obvious on the beaches at least), but as far as I know none of my personal friends sunbathed. I suspect it’s just a cultural thing.
Perth at peaks is about 2 average points higher than Auckland [0]. UV index does happen at peaks too.
I've met plenty people here who "never wore a hat their life" and look like a prune. Personally I'm more comfortable at home than trying to find a shade everywhere you go.
Don't know about Australia but when I was on Kerguelen island which is at the same latitude as my homeplace on the coast of France, there was a very noticeable difference in UV content, you could absolutely burn in just an hour without protection (and it happened often).
There are lots of other occasions to receive unhealthy doses of sunlight. And there are some activities that are like sunbathing, but people might not regard it as such, like reading a book, waiting at a bus stop, drinking a coffee outside, or walking at the beach.
Because asking a group of people how often they sunbathe is a horrible way to measure sun exposure. Dishonest answers, imperfect memory, differing definitions of sunbathing, and the idea itself that sunbathing and tanning is a proxy for overall sun exposure when they likely don't even make up a significant fraction of a person's UV exposure. Bad, bad, bad.
Because Correlation Is Not Causation™, and if they're doing correlation against self-reported data that involves people estimating things it's even less reliable. It still has value, yes, but that value is in finding things for more rigorous methods to examine, not in trying to draw conclusions from such shaky materials.
Is sunbathing even much of a thing anymore? I feel like I heard of people sunbathing in their yards or at the beach when I was younger (~20 years ago) but not so much now
I'm a middle-aged white-skinned American and I do it sometimes. Probably about 20 minutes per week in the summer?
I'm not trying to get a deep dark tan or anything. I just want to make my back and my chest match my arms and face a little bit more closely. Otherwise people laugh at you at pool parties!
I haven't delved deeply into the papers here. I'm not a doctor. But have seen in a few places that there is a correlation between latitude and all source mortality. Maybe it isn't just 'people that go outside tend to have a healthy lifestyle and that is why their mortality is lower'. A great Ted Talk on this (now a few years old) can be found here: https://www.ted.com/talks/richard_weller_could_the_sun_be_go...
It is a strange hypothesis. Living under a rock and avoiding sun exposure might kill you before you are able to reproduce. But, if you get past that point you will live long life under said rock.
For that to work, they don't have to be ancient. Just fit enough long enough to be too much of a net burden to the younger generations. The menopause seems to coincide with the age where people used to become grandparents.
Furthermore, people getting too old might make it harder for collective cultural knowledge to evolve. Which is fine in good times, but disadvantageous in volatile circumstances.
Longevity is a component in reproductive success since until quite recently in humans evolutionary past, the family played a crucial role in upbringing of the young generation. The more grandparents were missing, the harder it was for the young to survive since they tended to be less cared for.
It's possible that sick weak people are just too tired to want to go outside. In which case it's ill health that causes less sun exposure not the reverse.
Surprised no one is mentioning vitamin D. As I understood it, sun exposure is one of the few ways the body is supplied with this vitamin in a usable form.
Vitamin D is essential for the immune system so a correlation between a lack of sun exposure and ill-health seems almost so obvious it's a wonder it needs studying. What would be useful is the exact parameters around sun exposure/vit D metabolism.
Avoidance of sun exposure is mostly connected to more time spent indoors, where the ventilation is lower with higher CO2 buildup, viral exposure, and indoor pollution (mostly VOCs, but also Ozone, and also particulate and NO2 pollution (for gas stoves) from kitchens, etc.). However, outdoor time would have slightly more exposure to vehicular pollution, but likely less to nanoparticles in the case of gas stove usage (https://www.earth.com/news/gas-stoves-release-more-harmful-n...).
I may be wrong, but I understand vitamin D2 is a vitamin, but "vitamin D3" is in fact a hormone.
A vitamin is a building block, which by itself does nothing; a hormone is a directive, which instructs the body to do something - adrenaline, for example.
Vitamin D2 is a precursor / building block for the hormone D3.
So, outdoorsy people live longer because of the other health benefits of outdoorsy lifestyle, but are risking more skin cancer? But the risk of skin cancer isn't enough to outweigh the benefits?
Melanoma risk is driven by a number of factors. A white 40-something female who doesn’t tan and has heavy freckling has a risk close to 1% of developing a cancerous lesion in 5 years. If that person tans dark and has no freckles, that risk is 90% less.
My wife list a battle with melanoma - in her case a single severe childhood burn likely increased her risk by another 25-30%.
Given human instincts are so strong for getting a bit of sun you'd think there must be evolutionary advantage for doing so. Sunbathing, flying to different countries to get sun, the preference for sun tanned skin to pasty, and the whole difference in appearance between black people and whites seems to be an evolutionary response to letting more light in.
Presumably because we need the sun to make vitamin D.
My loose (and quite possibly wrong) understanding is that this is based on the notion of tanned skin being associated with lower-class women who spent time laboring outside and getting smelly/dirty versus rich and noble women who could sit inside all day.
In America, there is sometimes (often?) discrimination even within an ethnic group based on skin tone, e.g. lighter-skinned vs. darker-skinned African-Americans.
> Sunbathing, flying to different countries to get sun, the preference for sun tanned skin to pasty, and the whole difference in appearance between black people and whites seems to be an evolutionary response to letting more light in.
Aren't all of those purely cultural things that have actively changed over the last ~century?
I have one of the classic severe photodermatoses and, well, tough luck for me, I guess. I must take some fairly annoying measures if I wish to avoid pain and disfigurement.
As to the Vitamin D angle, the more I look into it, the more I see that it is a balancing act, and you need other supplements in a particular ratio for it to be more effective.
If you follow current WHO guidelines for sun exposure, you will avoid UV almost anywhere on planet. Apple’s Weather app (based on those guidelines) recommends all day sunscreen in Stockholm this entire week; same in Singapore, where it is overcast and rainy.
This Swedish paper’s summary does not differentiate between UV and sun, but assuming it concerns UV—the guidelines will seriously have to change, and ASAP:
> Nonsmokers who avoided sun exposure had a life expectancy similar to smokers in the highest sun exposure group, indicating that avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking.
It should be obvious that the linear no-threshold model of radiation danger is so weak that other findings are possible. After all, the human body has some repair mechanisms. Vitamin D is just the most well-known positive effect of sunlight.
Is there a correlation vs causation error here? Diet and exercise were not controlled.
Asian culture avoids sun exposure and sometimes exercise yet are healthier than their Western counterparts who have an unhealthy diet high in fats and sugar in addition to a sedentary lifestyle.
> similar sHR values were obtained when including exercise for those women who answered the second questionnaire in 2000
A bigger caveat tough is this is for Southern Sweden which is rather further north than where the average person in Asian lives. Even if one tries to avoid the sun, the considerably higher UV level and brighter sunlight likely someone is getting more sun than someone who avoids it in Sweden.
While the article seems focused on Vitamin D production, exposure to bright light has a wide range of positive effects on people from mood and sleep regulation to wound healing.
"Asian culture". Have you seen how the superelderly cohorts on Okinawa etc actually live? It's all outdoors.
Yes pasty sedentary 40 year old office workers in Beijing avoid the sun. That's not a longitudinal analysis, lifestyles have changed rapidly in the past generation.
Okinawans are a specific subset of centenarians with distinct lifestyle and diet, not quite representative.
What I mean is that Eastern Asian culture in general avoid the sun because pale skin is considered "more beautiful" vs. tanned for Western culture - ex: using umbrellas to cover sun.
Also, myopia epidemic in Asian countries is due to upbringing with strong emphasis in studying indoors but lacking encouragement for sports or outdoors activities: https://news.ycombinator.com/item?id=38782482#38783161
I hear that but what I am saying is that the cohorts whose longevity is being measured (ie, people dying now who were born in ~1950) grew up in an utterly different world and did not spend their adolescence indoors avoiding the sun, they were mostly rural, agricultural, poor, and outdoors.
We have no idea what the longevity of the current ~30yo urban east asian will be, but the lifestyle is so radically different than their grandparents that I don't think there's any value in connecting the two.
Are you saying that pretty much everyone trends healthier than anyone with a comparably more unhealthy diet, high in fats and sugar, with a more sedentary lifestyle?
I ask because, looking around at Americans, so genetically from all over the planet, with a large fraction from Europe, there's a huge dynamic range in diet and exercise levels and it really seems to correlate with the huge dynamic range in external presentation of fitness.
