Is Avoiding Sunlight as Dangerous as Smoking?
For decades, we’ve been warned that sun exposure = skin cancer. But research has uncovered a more complex story. It turns out sunlight may have life-saving benefits that challenge the “avoid sun at all costs” equation. Let’s deep dive into a Swedish study that suggests that avoiding the sun could shorten your life as much as smoking.
The Swedish Study: Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort
Lindqvist PG, Epstein E, Nielsen K, Landin-Olsson M, Ingvar C, Olsson J Intern Med. 2016;280(4):375-387. doi:10.1111/joim.12496
This 20-year study of nearly 30,000 women aged 25–64. Participants were grouped by sun exposure habits from those who avoided sun exposure at all costs to those who had the greatest sun exposure.
The findings:
Longer lives with more sun
Women who routinely soaked up the sun lived longer on average. They had significantly lower rates of death from heart disease and other non-cancer causes compared to women who avoided the sun. In other words, sunshine lovers were less likely to die of cardiovascular disease (like heart attacks or stroke) and illnesses other than cancer.
A trade-off with cancer risk
The proportion of deaths due to cancer was higher in the sun group, even though their overall survival was better. Because sun-exposed women were surviving longer, more of them eventually died from cancer, relative to the sun-avoiding group. This doesn’t necessarily mean the sun caused extra cancer; rather, by not dying early from heart disease, they lived long enough to reach ages where cancer is more common.
Sun avoidance is as bad as smoking
Non-smokers who avoided the sun had a life expectancy similar to smokers who got the most sun. In fact, over the 20-year follow-up, the total life span lost by shunning the sun was estimated at 0.6 to 2.1 years, comparable to the toll of smoking in this population. The authors concluded that avoiding the sun is a risk factor for death on a scale similar to smoking tobacco.
This caused a stir. After all, we know excessive UV exposure causes skin cancer. Could catching a few rays be that beneficial? Let’s explore some of the complicating factors.
The Skin Cancer Trade-Off
Skin cancer is the most common cancer worldwide, and UV exposure (from the sun or tanning beds) is the key culprit. Could the longevity gains from sunlight be offset by higher cancer risk? This is where things get tricky and opinions diverge.
In the Swedish study, even though the sun-exposed group had more cancer deaths by percentage, their overall mortality was still lower. Interestingly, the study did not find a higher rate of melanoma deaths in the sun-loving group versus the sun-avoiders.
Regardless, the American Academy of Dermatology (AAD) responded very firmly to the Swedish findings.¹ They expressed concern that studies like this might encourage people to seek more sun or use tanning beds, potentially raising skin cancer rates.
Dr. Abel Torres, president of the AAD, pointed out in a letter that the Swedish “no sun” group was relatively small and skewed older (ages 55–64) with more illness at baseline, so they might have had higher mortality for reasons unrelated to sun habit, In other words, perhaps sicker, older women both avoided sun and died sooner, confounding the results.The AAD also noted that all the sun exposure data were self-reported at the start of the 20-year period. People’s habits could have changed over two decades, and no updates were captured.
Crucially, the dermatology experts emphasized a point we can’t ignore: skin cancer is a major and growing public health issue. Each year in the U.S., about 5 million people are treated for skin cancers. The AAD worries that any message implying “sun exposure is good for you” might lead to more casual attitudes about UV protection, undoing decades of skin cancer prevention efforts.
Is It the Sun, or a Healthy Lifestyle?
One important question is whether sun exposure itself is the protective factor, or simply a marker of a healthier lifestyle. Think about it: if you’re the type of person who spends time outdoors hiking, gardening, or playing sports (thus getting sun), you’re probably getting exercise, fresh air, and social interaction, all of which improve health. The Swedish researchers did adjust for things like physical activity indirectly (and they even measured exercise in a subset). They argue that even after accounting for many lifestyle variables, the sun effect persisted. In their analysis, they tried different statistical models and even removed women with serious illnesses at baseline, and the benefit of sun exposure on survival remained strong.² The researchers acknowledge it’s tough to disentangle these effects completely. So, while the sunshine advantage in the data is compelling, we should be careful about leaping to causal conclusions.
So, where do we land?
On one hand, sunlight is clearly important for health, our bodies evolved to use it, and too little sun can indeed be harmful. The Swedish study and others like it are a wake-up call that zero sun may not be optimal for longevity. On the other hand, UV radiation can cause skin cancer, and indiscriminate sun-bathing or worse, tanning-bed use, is dangerous.
Moderation is key. Think of sun exposure like a vitamin – you want enough but not too much. Small, regular doses of sunlight are likely best.
Avoid burning and intense UV exposure. Dermatologists and the study authors actually agree on this point: sunburns are the enemy. The intensity of exposure matters. It’s far safer to get sun gradually (morning or late afternoon sun, or short midday exposures) than to save it all for a two-week beach vacation and fry yourself. Intermittent “binge” UV exposure and sunburn are strongly linked to melanoma. Regular moderate exposure is less so. Daily outdoor exposure aligns with our natural physiology, whereas what’s truly unnatural is cramming a summer’s dose of UV into a two-week vacation in Cancun or a 10-minute tanning bed session.
Consider your location and skin type. Sun advice isn’t one-size-fits-all. The Swedish study took place in a high-latitude country where UV levels are low most of the year (UV index <3 for ~8 months). In contrast, if you live somewhere near the equator or at high altitude (intense UV year-round), the margin for overexposure is smaller. Fair-skinned individuals (who burn easily) need to be more cautious with duration and timing than those with darker skin tones who have natural UV protection (but who, conversely, might be more prone to sunlight deficiency). Tailor your sun habits to your environment and your skin.
The challenge for health experts now is to craft guidelines that encourage people to get some sun for optimal health, while preventing the harmful outcomes of overexposure. While the guidelines slowly update, enjoy the sun sensibly: embrace regular daylight and outdoor activity, but avoid burning.
Join the waitlist for our Continuous Cortisol Monitor.
Dr. Jonathan Moustakis
Co-founder and CTO of Lume Health
References:
Torres, A. (2017), Response to ‘Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort’. J Intern Med, 281: 217-218. https://doi.org/10.1111/joim.12538
Lindqvist, P.G. and Olsson, H. (2017), Are low sun exposure habits a genuine strong risk factor for all-cause mortality or the result of bias?. J Intern Med, 281: 620-621. https://doi.org/10.1111/joim.12612
