Sun exposure is responsible for most of the visible aging of your skin—far more than all other factors combined. Yes, UV rays from the sun are the primary cause of wrinkles, pigmentation, sun spots, reduced skin elasticity, the degradation of skin texture, and many other signs of skin aging. In fact, many scientific estimates have shown that up to 80-90% of how young or old you look for your age is due to how much sun exposure you’ve sustained. And this has been shown repeatedly, in different parts of the world, over many years and in many different clinical studies. Here, we summarize the results from 11 different scientific research papers.
1. Sun Exposure May Cause Up To 90% Of The Visible Changes Attributed To Aging
The World Health Organization’s report called “Sun Protection: A Primary Teaching Resource” is dedicated to teaching people all about the health risks of UV radiation and how to protect yourself. In it the authors include information about sunlight, tanning, sunburn, skin cancer, eye inflammation, cataracts, and the fact that UV rays can reduce the effectiveness of your immune system—increasing your risk of getting sick. But they also briefly discuss the aging effect of the sun:
“Chronic overexposure to the sun can change the texture and weaken the elasticity of the skin. Sun induced skin damage causes premature wrinkling, sags and bags, and easy bruising. Up to 90% of the visible changes commonly attributed to ageing may be caused by sun exposure.”
2. UV Exposure Seems To Be Responsible For 80% Of Visible Facial Aging Signs
In this study, 298 Caucasian women were divided into two groups based on their history of sun exposure: either sun-seeking, or sun-phobic. They were also graded on the four main categories of visual aging signs: wrinkles/texture, lack of firmness of skin tissue, vascular disorders, and pigmentation heterogeneities (unevenness). The goal of the study was to determine how much of the visual signs of aging were due to sun and ultraviolet exposure as opposed to other external factors such as gravity and pollution, or lifestyle factors like diet, tobacco, illness, and stress.
The researchers found that there was a strong correlation between sun exposure and apparent age across all age groups. In particular, pigmentation disorders and wrinkles/texture are the most strongly linked to ultraviolet (UV) exposure. The conclusion:
“Clinical signs of aging are essentially influenced by extrinsic factors, especially sun exposure. Indeed UV exposure seems to be responsible for 80% of visible facial aging signs.”
3. Identical Twins With Significant Differences In Sun Exposure Have A Perceived Age Difference Of Over 11 Years
This research paper presents an overview of the current literature and research on the theories of facial changes of skeleton, soft tissue, and skin over time. As such it is a robust review. But in one part of the paper focused on aging, the medical doctors discuss an example of 61 year old twins who have experienced different levels of sun exposure. One twin had approximately 10 hours per week greater sun exposure than the other, while the later had a body mass index slightly higher than the former. The twin with greater sun exposure was perceived to be 11.25 years older.
4. Sun Damage Affects All Layers Of Your Skin
The objective of this study was to distinguish between skin changes produced by natural aging and skin changes produced by habitual sun exposure.
As it turns out, skin changes brought on by age are readily distinguishable from skin damage caused by sunlight. Sun exposure damages five major parts of the skin. This damage can cumulatively be termed dermatoheliosis, and it involves the epidermis (actinic keratosis), dermis (solar elastosis), blood vessels (telangiectasia), sebaceous glands (solar comedones), and melanocytes (diffuse or mottled brown patches).
“A century ago, it was considered vulgar by the middle and upper socioeconomic classes to have suntanned skin. Bodies were covered, and hats were worn to prevent sun damage. The only people who showed the effects of habitual exposure to the sun were outdoor manual workers.”
“After World War II, all this changed. Starting in the late 1940s, society decided that tanned skin looked healthy. The healthy tanned look was considered socially desirable. As a result, skin changes from habitual exposure to sunlight are now more common and more extensive and appear at an earlier age than they did in the 1940s. Elderly people now seldom exhibit skin changes associated solely with aging; some changes have been caused by habitual exposure to the sun.”
The consequences of sun exposure are both cosmetic and medical. “Cosmetic changes include leathering of the skin, increased wrinkling, and reddening. Medical changes include more frequent development of melanoma and nonmelanoma skin cancer, development of innumerable keratoses of various sorts, and the tendency of sun-damaged skin to get more easily irritated and bruised.
5. Cumulative Sun Exposure Is The Most Significant Controllable Factor In Skin Aging
In this study, relevant literature between 1977 and 2014 was studied for the principles of aging skin and how it relates to different ethnic groups. Intrinsic aging is related to an individual’s genetic background and occurs with the passage of time. On the other hand, extrinsic aging is associated with individual habits and relates to environmental exposures, health, and lifestyle; extrinsic aging includes sun exposure, diet, tobacco use, and exercise.
Regardless of skin type, the main signs of aging can be described clinically as wrinkles/texture, lack of firmness/elasticity and sagging skin, vascular disorders, and pigmentation heterogeneities—including sunspots. Yet differences in the concentration of epidermal melanin makes darkly pigmented persons more vulnerable to dyspigmentation, while a thicker and more compact dermis makes facial lines in darkly pigmented persons less noticeable.
The researchers conclude that of all extrinsic aging factors, cumulative sun exposure is the most significant, and skin of darker color is less susceptible to sun-induced damage. This is underscored by the fact that the appearance of aging in skin of color is less severe and typically occurs 10 to 20 years later than those of age-matched lighter-skinned counterparts.
6. Facial Sun Damage Is Significantly Correlated With How Old Women Look For Their Age
In this study, 102 pairs of female Danish twins were studied, along with 162 British females. The results show that how old women look for their age is significantly associated with skin wrinkling, hair graying, and lip height. The study also found that the appearance of facial sun-damage is significantly correlated with how old women look for their age—primarily due to its relationship with the appearance of wrinkles.
From the publication:
“The appearance of skin wrinkling is one of the main features indicative of the severity of sun-damage present in faces, predominantly when it appears alongside other features typical of sun-damage in exposed body sites. To determine the strength of relationship between sun-damage and perceived age, grading of the images for the presence of features consistent with sun-damage was carried out. Sun-damage was significantly and strongly correlated to the perceived age data generated from facial images in both the Danish twin and British populations supporting evidence that sun-exposure is associated with looking older for one’s age. In addition, both facial skin wrinkling and wrinkle depth in the crows feet area were significantly and strongly correlated to sun-damage in both populations after controlling for chronological age, similar to findings reported in the literature. Hence, chronic sun-exposure was likely to have caused some of the differences in skin wrinkling apparent between the younger and older looking [images of individuals].”
7. Repeated UVA Exposure Through A Glass Window Causes Photoaging
In this study, individuals with photoaging differences between one side of their face and the other–due to overexposure of one side of their face to sun through a window—were studied. The purpose of the analysis was to assess the visual impact on the skin of repeated ultraviolet-A (UVA) exposure of sunlight through a window. This is significant because UVA rays penetrate glass while UVB rays do not, so the difference in photoaging between the sides of the participants’ faces was due to UVA rays. Furthermore, UVA rays may not be blocked or absorbed by sunscreen lotions very well.
The results showed significant differences were observed for wrinkles, skin roughness, skin heterogeneity, skin hydration, and skin laxity (looseness) between the side of the face exposed to sunlight (UVA rays) through glass and the side that was not. The authors conclude that, “this study suggests the potential benefit of daily UVA protection during nondeliberate exposure indoors as well as outside.”
8. Your Wrinkle Number May Be A Good Marker Of Total Sun Exposure In Life
This study analyzed the facial skin condition of over 800 women and men living in a small community in Japan. It used quantitative methods to evaluate facial skin for hyperpigmentation, pores, texture, and wrinkling, and compared these to lifestyle information collected using a structured questionnaire.
Of all lifestyle factors, only two were predominately associated with skin condition among both men and women: smoking status and sun protection. Furthermore, the authors state that extrinsic aging (aging that isn’t genetic and therefore isn’t inevitable), “is the result of exposure to environmental factors, primarily ultraviolet irradiation.” And the number of wrinkles an individual has may be a good indicator of the amount of sun the individual has been exposed to in his or her life.
9. Your Number Of Wrinkles Is Significantly Related To Your Total Hours Of Lifetime Sun Exposure
In this study, two populations of people—one from a high sun exposure environment, and one from a low sun exposure environment—were examined. The two groups were examined for hyper-pigmentation and wrinkling using high-resolution digital video imaging. As expected, the people from the environment with high sun exposure had darker skin, higher facial hyper-pigmentation, and more facial wrinkles. Most significantly, the number of wrinkles was highly correlated with the total hours of life spent outside. Non-melanoma skin cancer was also highly strongly related to higher levels of UV exposure.
Just like in the previous study, these authors summarize that the number of wrinkles a person has may be a good indicator of total sun exposure in life.
10. Women With Lower Levels Of Sun Exposure Look 8-16 Years Younger Than Those With Higher Levels Of Sun Exposure
In this clinical study, 602 women ranging in age from 5 to 65 years who had lived their whole lives in either Kagoshima (in southern Japan) or Akita (in northern Japan) were analyzed. Using a variety of high resolution imaging and measuring technologies, the women were evaluated for facial skin wrinkling, hyperpigmentation, skin surface roughness (texture), skin color, skin hydration, sebum levels, and skin temperature. Kagoshima receives approximately 1.5 times more annual UVB radiation than Akita.
The authors conclude:
“Compared with Japanese women living in Akita [less sun], Japanese women living in Kagoshima [more sun] had significantly longer facial wrinkles, higher number of wrinkles, larger hyperpigmented spots, higher number of spots, rougher facial skin texture, more yellow foreheads and upper inner arms, darker foreheads, and less stratum corneum hydration in the cheeks and arms. When compared on an age-for-age basis, the average 40-year-old Kagoshima women has the same level of facial wrinkling as a 48-year-old Akita women, a delay of 8 years for living in the northern latitude. For facial hyperpigmentation, the delay is 16 years; the average 40-year-old Kagoshima women has the same level of facial hyperpigmentation as a 56-year-old Akita women. The results further testify to the skin damaging effects of sun exposure and may be useful in public health education to promote everyday sun protection.”
11. Repetitive Exposure To Solar UVR (Ultraviolet Radiation) Is Among The Principal Environmental Factors That Hastens The Aging Process Of Your Skin
Much of this research paper focuses on the many ways damage is done to stem cells in the skin by UV radiation (like that from the sun), and the relationship between stem cell damage and premature skin aging and cancer. A highlight of the paper includes these insights:
“Repetitive exposure to solar UVR (ultraviolet radiation) is among the principal environmental factors that can hasten the aging process of the skin, accompanied by progressive impairment of epidermal stem cell function…UVR is known to be a mutagen; long-term overexposure to sunlight is associated with photoaging and formation of skin cancers. Interestingly, both photoaging and cancer-inducing effects of UVR are mediated through UVR’s direct and indirect toxicity to the DNA.”
And the researchers summarize that:
“While melanin and enzymatic antioxidants serve as endogenous defense of the skin against UVR, accumulative exposure to UVR can overwhelm the skin’s defense mechanism. Exogenous and dietary antioxidants such as vitamin C (ascorbic acid), vitamin E (α-tocopherol), beta-carotenes, and different phytochemicals, particularly polyphenols derived from plants-based food and beverages, as well as herbal products that play a crucial role in maintaining redox homeostasis and antioxidant intervention, are thus proposed as being useful in delaying skin photoaging and helping to prevent skin cancer.”
Conclusion & What You Can Do
It’s obvious the sun damages your skin more than any other factor. So there is one natural conclusion from this research: don’t spend too much time in the sun if you don’t want to overly age your skin. While that may or may not be realistic, you can spend less time in the sun. And protect yourself when you are in the sun–especially since the UV radiation that reaches us only seems to be increasing, and the nutrients we get in food that help protect us from UV exposure keep decreasing. You can also use an anti-aging pill that provides certain antioxidants from foods and plants proven to help protect your skin (and eyes) from sun damage. Even small changes in your habits over time can have a beneficial effect.
1. World Health Organization Sun Protection – A Primary Teaching Resource 2003 http://www.who.int/uv/publications/en/primaryteach.pdf
2. Effect of the sun on visible clinical signs of aging in Caucasian skin http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3790843/
3. The Science and Theory behind Facial Aging http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4174174/
4. Elderly and sun-affected skin: Distinguishing between changes caused by aging and changes caused by habitual exposure to sun http://www.ncbi.nlm.nih.gov…11421052.pdf
5. Aging Differences in Ethnic Skin http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4756870/
6. Why Some Women Look Young for Their Age http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2779449/
7. Assessment of cumulative exposure to UVA through the study of asymmetrical facial skin aging http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2946854/
8. Lifestyle Factors and Visible Skin Aging in a Population of Japanese Elders http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3924128/
9. Influence of chronic UV exposure and lifestyle on facial skin photo-aging–results from a pilot study. http://www.ncbi.nlm.nih.gov/pubmed/10709362
10. Quantitative evaluation of skin condition in an epidemiological survey of females living in northern versus southern Japan. http://www.ncbi.nlm.nih.gov/pubmed/11514124
11. Ultraviolet Radiation-Induced Skin Aging: The Role of DNA Damage and Oxidative Stress in Epidermal Stem Cell Damage Mediated Skin Aging http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4842382/