Health Effects of Sun Exposure: What Are the Benefits of Sunlight?

Most people enjoy the feeling of sunshine on their skin or spending long days at the beach.

But while sunlight has many positive benefits to overall health, including vitamin D production, mood support, and cognitive function, excessive exposure to ultraviolet radiation from the sun also has several potential downsides to consider.

In this article, we’ll discuss the pros and cons of sun exposure, including how to safely reap the benefits of sunshine without falling into risky territory.

Top Health Risks of Sun Exposure

Although there are benefits of sunlight, there are also plenty of risks of sun exposure to consider, including developing skin cancer, premature aging, and heat-stress-related illnesses.

That said, these downsides will likely only occur if you are exposed to the sun for too long, too often, or without adequate sun protection.

Increased Risk of Skin Cancer

Most people know that a leading risk of excessive sun exposure is developing skin cancer. While there are potentially other causes, 90% of skin cancers are from too much sun. 

The same ultraviolet (UV) rays that can benefit us in moderate amounts also have the potential to harm us.

As with most things in life, moderation is key, and the dose makes the poison. With excessive sun exposure, UV rays are absorbed into the skin, leading to redness, burns, and, eventually, cancer growth.

According to researchers from The University of Texas M. D. Anderson Cancer Center, the first step in UV-induced carcinogenesis is DNA damage, which disrupts normal cellular processes. 

This DNA damage leads to mutations, followed by inappropriate gene expression. Skin cells can then grow uncontrollably because they are resistant to apoptosis, a regular programmed cell death that eliminates unneeded cells and prevents cancer cell growth. 

While UVB (ultraviolet B) rays pose a much greater risk to skin cancer development than UVA (ultraviolet A) rays, excess UVA radiation can accelerate the damaging effects of UVB by generating free radicals and causing DNA damage in the skin.

The most common skin cancers include:

• Basal cell carcinoma: This form of skin cancer begins in basal cells, which are small, round skin cells in the base of the epidermis, the outer layer of the skin. Basal cell carcinoma looks like a flesh-colored round growth, a pearl-like bump, or a pinkish patch of skin. It’s the most common type of skin cancer and often develops after years spent in the sun or using tanning beds. While basal cell carcinoma spreads slowly and is less likely to metastasize (spread), it can grow deeper under the skin if untreated, causing destruction to surrounding tissues and even fatality. 
• Squamous cell carcinoma: This skin cancer forms in squamous cells—flat skin cells in the outer part of the epidermis that constantly shed as new ones form—and is more likely to metastasize. Squamous cell carcinoma looks like red firm bumps, scaly patches, or sores that continually reopen, with more common occurrences on skin with frequent sun exposure, like the face, neck, arms, ears, and chest. 
• Melanoma: The most serious and deadliest form of skin cancer, melanoma has the greatest tendency to metastasize or spread throughout the body. Melanoma can develop within a mole you already have, which is why it’s essential to check your moles for changes in Asymmetry, Border, Color, Diameter, and Evolution—aka the “ABCDEs” of melanoma warning signs. Melanoma can also appear suddenly as a new dark spot on your skin, and early treatment and diagnosis are critical.

There are also several less common types of skin cancer, including dermatofibrosarcoma protuberans (DFSP), Merkel cell carcinoma, and sebaceous carcinoma. 

According to the Skin Cancer Foundation, 1 out of every 5 Americans will develop some type of skin cancer by age 70, and having 5 or more sunburns in your life doubles your risk for melanoma. On the bright side, the 5-year survival rate for melanoma is 99 percent when detected early—getting your skin checked by a dermatologist annually is ideal. 

Premature Aging

If you’ve ever encountered a self-proclaimed beach bum in their later years, you know the effects that excess sun exposure can have on the skin. 

Ultraviolet A (UVA) rays from the sun penetrate deeply into the skin and can cause DNA damage and free radical production, which is the leading cause of photoaging—another term for skin with sun damage.

Photodamage from UVA occurs in the deepest layers of the skin—the dermis—and it can take years before the damage becomes visible. This is why people who loved to tan in their youth don’t see the full extent of their sun-worshipping ways until much later in life.

However, some signs of photoaging can begin to develop as early as your 20s (and get worse as the years go by), including:

• Wrinkles
• Age spots, liver spots, and freckles
• Loss of skin tone (decreased elasticity)  and thinner, drier skin
• Rough, uneven skin texture, including leathery skin
• Broken capillaries or spider veins, especially around the nose and chest
• Redness and blotchiness

Most of these changes occur because UVA rays damage collagen and elastin fibers that give your skin its youthful appearance, tautness, and elasticity. UVA rays also damage epidermal cells and capillaries, leading to redness and blotchiness. 

According to dermatology professors Laure Rittié and Gary J. Fisher at the University of Michigan Medical School, “In general, alterations of skin structure and function appear earlier and are more pronounced in photoaged than in chronologically aged skin. Evidently, photoaging is a cumulative process and, as such, is more severe in older individuals.”

Cataracts

Overexposure to UV radiation can also cause cataracts. Although not the only cause, about 20 percent of cataract cases are due to excessive sun exposure. 

Cataracts are characterized by a clouding of the eye’s lens and are a leading cause of vision loss, as they impact the eye’s ability to focus on light.

In one study of almost 10,000 people living in India, sun exposure significantly increased the risk of cataracts. The prevalence of cataracts increased with greater lifetime sun exposure. Specifically, 66.4% of those in the highest sun exposure group developed cataracts, while 16.7% of people in the lowest category did. 

Excess UV radiation can also cause other eye problems, including pterygium (tissue growth that can block vision), skin cancer around the eyes or eyelids, and macular degeneration. 

The best way to minimize your risk of UV-induced cataracts and eye damage is by protecting your eyes from the sun, including wearing UV-blocking sunglasses and limiting exposing your eyes to the sun when it’s at its strongest (typically between 10 a.m. and 4 p.m.)

Sunburn and Heat Exhaustion

Excessive and prolonged exposure to the sun, especially during midday, can cause sunburns, heat exhaustion, or heat stroke. 

Sunburns develop when UV radiation exceeds the protection your skin’s melanin can provide. A moderate amount of UV radiation causes the skin to tan, but sunburn is your skin’s response to UV-induced sun damage. 

While you may think a sunburn is simply an annoying part of vacation, it increases your risk of skin cancer and photoaging. Severe sunburns can also cause dehydration and shock, which can include fainting, low blood pressure, and weakness.

Excess sun can also lead to heat-stress-related illnesses, including heat exhaustion and heat stroke.

Heat exhaustion is the first stage, characterized by headaches, dizziness, nausea, heavy sweating, and weakness. It can progress into heat stroke, which is very serious and ​​occurs when the body can no longer control its temperature. Common symptoms of heat stroke include confusion, loss of consciousness, profuse sweating, and seizures, and it must be medically treated immediately. 

Are There Benefits of Sun Exposure?

While those risks certainly don’t sound great, there are also plenty of benefits that come from moderate sun exposure (keyword: moderate). 

For a detailed look at the benefits of sun exposure, head over to this article. 

Briefly, the benefits of moderate sun exposure include:

• Increased vitamin D production
• Improved mental health and mood, including a reduced risk of Seasonal Affective Disorder 
• Circadian rhythm regulation
• Improved sleep 
• Increased bone strength
• Improved cardiovascular and metabolic health 
• Improved cognitive function (in the short and long term)

How to Safely Get Sun Exposure

Sun safety is incredibly important, no matter the season or weather outside. 

To safely get sun exposure, don’t go outside without sun protection for more than 10 to 15 minutes, or possibly less if you have fair skin. People with fair skin are at higher risk of developing adverse effects from more sun exposure. 

Avoid going outside without sun protection during the time of day when the sun’s damaging rays are the strongest, typically during the peak hours of 10 a.m. and 4 p.m. 

Other sun safety tips include:

• Wear sunscreen. Use a broad-spectrum sunscreen of SPF 30 or more that protects against both UVA and UVB rays. You should be applying sunscreen every two hours or more often if you go swimming or are sweating. Use mineral-based sunscreen with ingredients like zinc oxide or titanium dioxide that physically reflect UV rays. Don’t forget your scalp, ears, back of neck, and lips (use an SPF chapstick). Don’t be fooled if it’s cloudy out—wear sunscreen in all weather. 
• Wear protective clothing. Shirts with long sleeves, pants, wide-brimmed hats, and sunglasses can protect you from the sun during outdoor activities. Look for protective clothing with a UV protection factor (UPF) or made of a tightly woven fabric.
• Avoid tanning beds. It’s not the 2000s anymore; no one should be using a tanning bed! Enough said. 
• Seek shade. Use umbrellas or seek other sources of shade to provide additional sun protection during the hottest part of the day. 
• Be aware of your medications. Many over-the-counter and prescription medicines increase the skin’s sensitivity to UV rays, so be aware of their side effects on light sensitivity. Some medications that increase sun sensitivity include some antibiotics, birth control pills, topical benzoyl peroxide, and retinol products. 

Sunlight FAQs