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Benefits of Sunlight for Physical Health

Boosts Vitamin D Levels

The best-known benefit of sunlight is a boost in vitamin D levels. When skin is exposed to the sun’s rays (UVB), a chemical reaction occurs that ultimately leads to the creation of Vitamin D. Vitamin D, also called the sunshine vitamin, plays an important role in hundreds of processes in the body, including calcium metabolism, neuromuscular function, and the body’s ability to fight infections. Vitamin D deficiency often results from reduced exposure to direct sunlight, below what is recommended or ideal. 

Improves Bone Health

Sun exposure is the main source of vitamin D production in the skin. Vitamin D plays an essential role in the absorption of minerals such as calcium and phosphorus, which are needed for bone mineralization. Prolonged and severe vitamin D deficiency is a known cause of rickets in children and osteomalacia in adults (weakened bones). Therefore, sunlight exposure is important for healthy bones and to prevent osteoporosis (weak and brittle bones).

Supports the Immune System

As mentioned, exposure to UV rays in sunlight is essential for vitamin D synthesis. There is scientific evidence that vitamin D modulates immune responses. Deficiency of vitamin D is linked to an increased incidence of autoimmune diseases and a higher risk of infections. 

Regulates Blood Pressure

The American Heart Association reports that exposure to UV sunlight is linked to lower blood pressure (specifically, systolic blood pressure or the first number in a blood pressure reading). This effect is small but significant and more prominent in people with light skin compared to those with darker skin.

Promotes Wound Healing

Exposure of the skin to UV light causes increased blood flow in the tiny blood vessels under the skin’s surface. It also has a bactericidal effect (kills bacteria). This helps in healing skin wounds by bringing white blood cells to the wound site and creating an inflammatory response.

Relieves Symptoms of Skin Conditions

Psoriasis is a skin disorder in which gray or silver scales develop due to an overgrowth of skin cells caused by increased activity of the immune system. Many people with psoriasis report an improvement in their symptoms in the summer months or after moving to a sunny climate. Scientists believe sunlight helps psoriasis symptoms because UVB rays have anti-inflammatory effects and reduce the rate of skin cell turnover.

Note: Sunlight exposure can be an eczema trigger for some people, but moderate sun exposure may help clear up eczema for others. Read more: “Eczema Vs Psoriasis: What’s The Difference?”

Lowers Cancer Risk

Excessive sun exposure is a well-known cause of skin cancers such as basal cell carcinoma, squamous cell carcinoma, and melanoma. 

However, while too much sun exposure increases the risk of skin cancer, sunlight exposure protects against other types of cancer. People living at lower latitudes with more sun exposure have a decreased risk of many types of cancer, including Hodgkin lymphoma, breast cancer, ovarian cancer, pancreatic cancer, colon cancer, prostate cancer, and others. 

Other Health Benefits

Low vitamin D levels are linked to a range of medical conditions. More research is needed, but it is possible that sun exposure and vitamin D production may have a protective effect against conditions such as: 

• Multiple sclerosis

• Type 1 diabetes mellitus

• Metabolic syndrome (a group of conditions that increases the risk of type 2 diabetes and cardiovascular disease)

• Rheumatoid arthritis

• Asthma

• Infectious diseases

Mental Health and Emotional Advantages of Sunlight

Elevates Mood and Energy Levels

Sun exposure can elevate mood and energy levels by increasing serotonin levels in the brain. Serotonin is a neurotransmitter (natural chemical) that plays a role in regulating happiness, hunger, sleep, body temperature, sexual function, learning, and memory.

Reduces Anxiety and Combats Depression

Seasonal affective disorder (SAD) is a type of mood disorder that occurs in certain seasons (typically the fall and winter months in the northern hemisphere when there is little sunlight). Scientists have found that less sunlight and shorter days lead to neurochemical changes in the brain that increase the risk of developing depression. Lack of natural sunlight exposure is one of the main reasons why people develop seasonal affective disorder. 

Spending time outdoors or sitting near a window can ease the symptoms of SAD and major depression. If increased sunlight exposure is not possible, light therapy with artificial light sources may help. 

Improves Sleep Patterns

Light plays a vital role in regulating the circadian rhythm, which is the body’s internal clock that controls sleep-wake patterns. In addition, light affects the production of melatonin—the brain makes this sleep-promoting hormone in response to darkness. 

Exposure to natural sunlight ensures that your circadian rhythm is closely synchronized with natural daylight hours. This allows you to stay awake during the day and sleep when it’s dark. In contrast, poorly timed exposure to artificial lights, such as light from a cell phone screen before bedtime, can throw your circadian rhythm out of whack and misalign your sleep-wake cycle.

Enhances Cognitive Function

Studies have found that decreased exposure to sunlight is associated with an increased risk of cognitive impairment. Therefore, UV light exposure may promote cognitive function, including your ability to think, remember, learn new things, concentrate, and make decisions. 

How Much Sunlight Do You Need Per Day?

Factors that Influence Your Sunlight Needs

Many of the health benefits of sunlight are linked to vitamin D production in the skin. The process of vitamin D synthesis in the skin is influenced by various factors, including:

• Exposure to UV Radiation (UVR): Your UVR exposure depends on various factors such as latitude, altitude, atmospheric ozone levels, pollution levels, and season. For example, the amount of UVB radiation declines at higher latitudes, leading to reduced vitamin D production. During the colder winter months of the year, people wear more clothing, thus reducing sun exposure.

• Amount of Skin Exposed to the Sun: Behavioral and cultural factors affect dressing practices. The use of sunscreen can also affect vitamin D synthesis and the health benefits of sunlight. Additionally, the amount of body fat can affect sunlight absorption by the skin.

• Skin Type: The amount of melanin affects the ability of the skin to produce vitamin D. In a person with fair skin, half an hour in the summer sun in a bathing suit can lead to the release of 50,000 IU (international units) of vitamin D into the blood circulation within 24 hours. The same amount of sun exposure in a tanned individual produces about 25,000 IU of vitamin D, and in a dark-skinned person under 10,000 IU of vitamin D. Therefore, people with darker skin tones need 5-6 times more sun exposure than people with lighter skin for equivalent vitamin D production.

Recommended Daily Sun Exposure

Research suggests that 8-30 minutes of sun exposure around midday in the spring and summer months with 25% of the body exposed (face, neck, arms, and hands) is enough to make sufficient amounts of vitamin D. However, up to 2 hours of sunlight exposure at noon is necessary for the winter months when only about 5-10% of the body is exposed. 

Note: People with darker skin tones need to spend more time in the sun to make the same amount of vitamin D as fair-skinned individuals.

Risk Factors for Inadequate Sun Exposure

Risk factors for inadequate sun exposure and vitamin D production include disabilities that make it harder to spend time outdoors, age (infants may not go outdoors enough, and elderly individuals make vitamin D less efficiently), dark skin, and living in northern latitudes during the winter.

Safe Ways to Enjoy Sunlight

Best Times of Day for Sun Exposure

Studies have shown that the body makes vitamin D most efficiently around noon. This is also the time when the sun is at its highest point and UVB rays are strongest. Therefore, you need to spend less time in the sun at noon to make enough vitamin D compared to other times of the day.

Use of Sunscreen and Protective Clothing

The use of sunscreen and protective clothing (long-sleeved shirts and pants, hats, sunglasses) can decrease the formation of vitamin D in the skin. The exact effect of sunscreen depends on how much of your body you apply sunscreen, how thick a layer of sunscreen you apply, and the SPF level. Doctors still recommend the use of sunscreen to protect against the harmful UV rays (UVA).

Balancing Sunlight and Shade

Too much sunlight can be harmful. Public health experts, therefore, advise striking a balance between getting enough sun to make vitamin D without increasing your risk of skin cancer. Your aim should be to get moderate sun exposure, for example, 8-30 minutes of midday summer sun at least 3 times a week.

Concerns About Sunlight Exposure

Risks of Too Much Sun

Excessive sun exposure is a known cause of skin cancer. It can also damage the eyes, negatively affect the immune system, cause premature aging of the skin (photo-aging), and increase the risk of heat stroke.

Sun Safety Tips

The American Academy of Dermatology recommends the following sun safety tips:

• Wear protective clothing such as long-sleeved shirts and pants, a wide-brimmed hat, sunglasses, and lip balm when outdoors. 

• Use a broad-spectrum, water-resistant sunscreen with at least SPF 30 (Sun Protection Factor) on exposed skin. When wearing sunscreen, don’t forget to reapply it every 2 hours and after sweating or swimming.

• Stay in the shade between 10 am and 4 pm when the sun's rays are strongest. A good rule of thumb is to seek shade if your shadow is shorter than you. 

• Be extra cautious around snow, sand, and water. The reflection of the damaging rays of the sun can increase your risk of sunburn. 

• Get vitamin D by eating a healthy diet and/or taking vitamin D supplements.

Alternatives to Natural Sunlight

The use of a light therapy box can provide relief from conditions such as seasonal affective disorder (SAD). This device provides a type of light therapy that mimics natural light and causes chemical changes in the brain to uplift mood.

Doctors advise against using tanning beds. The ultraviolet light in tanning beds is linked to a higher risk of skin cancer and premature skin wrinkling.

Frequently Asked Questions About Sunlight

What are the 5 benefits of the sun?

The top 5 health benefits of sunlight include increased vitamin D formation, stronger bones, enhanced immunity, improved mood, and better sleep quality.

What does sunlight do for the body?

Getting enough sunlight can have significant health benefits for the body. Many of the benefits of sunlight for human health are linked to its ability to help the skin make vitamin D. Vitamin D is an essential nutrient that plays an important role in hundreds of processes in the body, including bone health and immunity.

Why is sunlight good for the brain?

Exposure to sunlight releases a hormone called serotonin in the brain. Serotonin helps to boost mood and energy levels and keeps you calm and focused.

How much sun do I need a day?

The recommended UV radiation exposure is 8-30 minutes of midday natural sunlight several times a week. People with a darker skin tone may need a little more. Caution should be taken in individuals taking medication that causes photosensitivity.