This is not what the study said, but the in the part highlighted quite the opposite.
Q: Is it healthy to sunbathe without sunscreen?
Yes and no. Yes, for a short amount of time (depending on skin type, etc). Yes, for that short amount of time it is 'healthier' than with sunscreen, because you get the useful UV rays. No, it is not healthy to sunbath longer than your skin 'can afford it', compensate for the damages it incurs (that would strictly mean: no, sun-bathing is never a terribly good idea, limited and varied sun exposure is. Sunscreen blocks UV lights, blocks Vitamin D synthesis etc, but does not much to prevent skin cancer, so the worst conclusion to draw is: 'With sunscreen I may bathe for a looong time.'
'Suncreen […] does not do much' means — especially in the context of sun bathing as questioned, but also even within the larger context of ' adequate exposure'/avoiding cancer-risks:
Useful sunscreen recommendations are embedded in a list of measures, ranking fairly low on its own:
Risk Reduction Behaviours
Protective measures against solar ultraviolet radiation is particularly important for persons at increased risk and must be applied in the following order:
- avoidance of exposure to strong solar radiation,
- wearing suitable clothing,
- using sunscreens.
Strong Consensus (100%)
Avoidance of Strong Solar Radiation Exposures
The following measures must be taken to avoid exposure to strong solar radiation (taking into account the type of skin):
- At medium and high UV irradiance (UVI 3-7), seek shade during midday,
- In the case of very high UV irradiance (UV index 8 and higher), avoid going outdoors during the midday period if possible. If this is not possible, seek shade,
- If necessary, postpone outdoor activities to the morning and evening
- Avoid sunburn.
Strong Consensus (100%)
Wearing Appropriate Clothing
- When staying outside in the sun, suitable clothing, headwear and sunglasses should be worn for protection.
Use of Sunscreen Products
- Appropriate sunscreen products should be used for skin areas that cannot be protected in any other way. The use of sunscreens must not result in a prolonged stay in the sun.
Consensus (87%) […]
There is contradictory data on whether the risk of melanoma is reduced by sunscreen use.
Strong Consensus (97%)
— German Guideline Program in Oncology | Prevention of Skin Cancer | Version 2.1 | August 2021. PDF
That is resonant with the following finding, that does not even lift sunscreen into the abstract, but emphasises again that natural sun light and UV exposure should be sought, in a reasonable amount, (which to me excludes any prolonged sunbathing, and especially prohibits even longer sunbathing 'because my smear-on paste protects me and others'):
Collectively, this evidence indicates it would be wise for people living outside the tropics to ensure they expose their skin sufficiently to the sun. To minimize the harms of excessive sun exposure, great care must be taken to avoid sunburn, and sun exposure during high ambient UVR seasons should be obtained incrementally at not more than 5-30 min a day (depending on skin type and UV index), in season-appropriate clothing and with eyes closed or protected by sunglasses that filter UVR.
— Lars Alfredsson et al.: "Insufficient Sun Exposure Has Become a Real Public Health Problem", International Journal of Environmental Research Public Health, Jul 13;17(14):5014, 2020. doi: 10.3390/ijerph17145014. PMID 32668607
In terms of 'risk of malignant melanoma' (as perhaps the best known form of skin cancer), reliance on sunscreen is counterproductive. That is: no one should get exposed any longer with sunscreen than one would otherwise, or the risk for melanoma increases a lot. In other words, for melanoma sunscreen is much less effective than often thought, and applying sunscreen often leads to 'risk-compensation behaviour' diminishing any protective effect it might have had.
Almost the same is true for complete avoidance of sunshine. Fear communication and other factors have led some people to avoid any sunshine at any cost, which in this case is simply a shortened lifespan, since sunshine is a necessary ingredient for healthy life. the dosage makes the poison, and too little sunshine is costly for longevity, as is too much sunshine. The 'public health' 'advice' to 'avoid any sunshine unless using sunscreen' is the culprit here, as it just backfires. This advice turned out as unhealthy.
The gist is: do try get some sun, do not avoid it completely, but never overdo it, not even if your sun-blocker or your public-health-guru-promoting-bullshit promise marvellous things about it. And remember that sun screens or sun blockers are designed to block certain UV rays, which are useful for maintaining health when absorbed by the skin in the correct dosage, and not just for vitamin D, although it is concerning enough that rickets alone make something of a comeback with increased sun screen usage.
The problem with 'getting your sun' is that it will increase the rate of photo ageing, and it will increase the rate of skin cancer! That sounds bad, but also means that you may die of skin cancer when getting adequate sun exposure, but yiou would have died a few years earlier of for example cardio-vascular problems. No one will live forever, it is a trade off.
This study actually says:
Further, because there is no robust evidence to show that it is safe in terms of MM [malignant melanoma] to be exposed to the sun for longer after applying sunblocker, we question the general interpretation of the guideline that ‘as long as you use sunblock you may stay out in the sun for a long time’.
An intriguing explanation for the rising MM incidence in Sweden is that the restrictive sun exposure advice that urges reliance on sunscreen use has resulted in overexposure, which is a major risk factor for MM. More importantly, strong recommendation to avoid sun exposure may have increased the risk of CVD and noncancer/non-CVD morbidity and death in the Swedish population. Greater focus on this risk might help in generating causal data.
— P. G. Lindqvist, E. Epstein, et al.: "Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort", Journal of Internal Medicine, Oct; 280(4):375-87, 2016. doi: 10.1111/joim.12496.
The Harvard Health bloggers summarise this nicely:
Can the sun extend your life?
With summer just around the corner, this news is timely — and a great excuse to get out of the house or office and soak up some sun. But there are some important caveats about this research:
Deaths due to cancer were more common among those who spent more time in the sun (The authors suggest that the higher probability of being diagnosed with cancer among the sun worshippers was because they were surviving longer and not dying as often of other causes)
The impact of sun exposure on longevity was relatively small. Even those with the greatest sun exposure only benefited from an extra 7 months to 2 years of life.
This study detected an association between sun exposure and a lower frequency of certain causes of death; however, that’s not the same as proving that sun exposure was the cause of longer life. It could turn out that there is another explanation for these results that has little to do with sun exposure itself. For example, perhaps people with more sun exposure tend to be more active, smoke less, and have healthier diets. The researchers tried to account for other factors such as these in their analysis, but it’s always possible that something important was overlooked.
The reason why more sun exposure might prolong life or prevent heart disease deaths could not be determined by this study. Because the sun’s UV light triggers chemical reactions in the skin that lead to the production of vitamin D, it’s possible that vitamin D is responsible for the health benefits of sun exposure described in this study. And that could mean vitamin D supplements would promote longer life free of heart disease, even without sun exposure. However, that’s only speculation and prior studies have not been able to prove this.
The study did not include men. The impact of sun exposure could be quite different among men.
Before you ditch the sunscreen and head for the beach…
While there is some uncertainty about the overall importance of this study, one thing is for sure: when it comes to the impact of sun exposure on health and disease, the findings of this new report won’t be the last word. There are competing risks linked to sun exposure: skin cancer and other skin damage are clearly a risk; but there may be health benefits as well (as suggested by this study). Since this type of study cannot determine the exact reason that those with more sun exposure lived longer, we’ll need more research to sort out just how much sun exposure is best.
The authors of this study speculate that recommendations to limit sun exposure might actually do more harm than good; in fact, they suggest that avoiding the sun could have a negative health impact similar in magnitude to smoking. That’s quite a statement!
More popular takes on these findings here — Business Insider: "Why Avoiding Sunshine Could Mean An Early Death In Women" (reprint of Telegraph article), Daily Mail: "Could the sun help us live to a ripe old age? Women who soak up the rays twice as likely to be alive 20 years later than those who actively avoid them"