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The Science of Sunlight and How it Can Impact Longevity

By Kiran Kumar, September 19, 2022

Sun exposure and aging have a strange relationship. In some cases, sunlight can promote overall health and extend lifespan. In other cases, it can lead to life-threatening chronic illness and accelerate aging.

So how do we strike a balance between not enough sun, and way too much? And what are the different ways sunlight can help or harm us?

The Controversy Behind Sunlight

Many people avoid sunlight like the plague. There is scientific evidence that demonstrates how prolonged sun exposure, without adequate protection, can accelerate aging and damage skin cells. However, with the right precautions, sun exposure isn’t all that bad and actually comes with a plethora of benefits!

How Sunlight Can Promote Health and Longevity

There are multiple biological elements that react and rely on sun exposure to support overall well-being and longevity! Let’s take a closer look at a few of them.

Circadian Rhythms

Circadian rhythms regulate and synchronize our 24-hour cycle of biological processes. Headquartered in the hypothalamus, a small region in the brain, a consistent circadian rhythm is critical for both health and longevity. (Read more about the importance of circadian rhythms for longevity here!)

Circadian rhythms are mainly internal, but they do respond to light exposure. Essentially, light informs our hypothalamus that it’s daytime and it adjusts our internal clock accordingly. Exposure to natural light stimulates cortisol production, and inhibits melatonin production to keep you bright-eyed and bushy-tailed! 1

That’s why being in the sunlight during the daytime, and in the darkness during nighttime, validates our circadian rhythms and encourages longevity.

Vitamin D Levels

The UV radiation that comes with sun exposure boosts our vitamin D Levels. UV type B radiation mingles with a specific skin protein, referred to as 7-Dehydrocholesterol, and converts it into an active form of vitamin D2.

Only some foods contain vitamin D, such as fatty organic fish and organic egg yolk. This makes sun exposure our most important source of vitamin D. 3

There is evidence to suggest that healthy vitamin D levels can help prevent a number of serious illnesses. This includes stroke, hypertension, type I diabetes and rheumatoid arthritis. 4,5 Vitamin D can also fight infections such as the flu and COVID-19. 6

Vitamin D even promotes a better mood! There is a powerful correlation between low vitamin D levels and poor mental health. Although it’s not clear whether the deficiency induces poor mental, vitamin D supplementation is able to battle depression-like symptoms and anxiety. 7 Vitamin D may also support diet-induced weight loss, specifically belly fat. 8

Mental Health

Daily walks on the treadmill just don’t have the same oomph to them. But strolling outdoors on a nice sunny day can really put a smile on your face.

Spending time in the golden sunlight can stimulate the production of serotonin, a chemical that behaves as a natural antidepressant and lowers your risk for depression and anxiety. 9 Light exposure also elevates cortisol production and inhibits melatonin production, increasing alertness! This means that the sun actually nurtures better mental health.

How Sunlight Can Promote Disease and Aging

Too much sun, with insufficient protection, leads to sun damage. Sun damage is known to increase an individual’s biological age, accelerating aging at the cellular level. 10

Cellular Senescence

Sun exposure, without proper care, can actively generate zombie cells.

Zombie, or senesecent, cells come about when a normal cell takes a lot of DNA damage and enters a transient state called senescence. Cellular senescence should routinely trigger apoptosis (programmed cell death) but, occasionally cells will go rogue and stay alive. These little rebels become a big issue.

DNA damage can naturally accumulate with time or can be accelerated by stressors such as free radicals. (Read more about using antioxidants to fight free radicals here!) UV radiation from sunlight is a predominant stressor and source of DNA damage. This radiation creates severe breaks in DNA structure and prematurely sends cells into senescence.

Prolonged cellular senescence is one of the nine fundamental hallmarks of aging.11 Zombie cells cause inflammation and are known contributors to several age-related diseases including arthritis, several cardiovascular illnesses, and cancer. 12

Skin Cancer

Cancer cells are often a result of DNA mutations. Our cells have genes that are designed to prevent tumors and cancer such as the p53 gene. If these genes mutate, you are left with a cancer-prone cell. 13

When UV radiation damages DNA, it is subsequently repaired. Sometimes, the damaged DNA molecule is replaced incorrectly, creating a mutation. So, UV radiation can induce DNA mutations and produce cancerous cells. That’s how sun-damaged skin increases the risk of skin cancer. 14

The Perfect Balance

Sunlight is all about moderation, and proper care. Here are some steps you can take to get your fill of sunlight, without taking too much damage:

  • Keep an eye on the UV index in your region. Avoid excessive sun exposure when the index is at five or higher.
  • Always wear sunscreen, even when it’s overcast. UV radiation is still around you and can still damage your skin, even when it’s cloudy. Try to stick with an SPF of 30 or higher, and remember to reapply.
  • Keep your skin covered. A thin cover can go a long way, especially dark colored fabrics.
  • Know your skin. If your skin is lighter, and more sensitive to sunlight, you may not need as much time outdoors to fill your quota. If you have darker, pigmented skin, you can spend much more time basking in the sun! 15
  • Maintain skin health. Maintaining a healthy diet can promote skin health and resistance to sun damage. Consider integrating tomatoes, sweet potatoes, berries, and fatty fish into your diet. 16

Typically, for light-skinned individuals, you should not exceed 30 minutes of direct sun exposure daily. Darker-skinned individuals need to spend more time in the sun, sometimes hours, to absorb some of the benefits. This varies based on the UV index and time of day. 15

Sunlight is obviously a force to be reckoned with, but also one we can take advantage of!

Takeaways

  • Sun exposure has a number of benefits. Being in the sun during the daytime validates our circadian rhythms and encourages longevity. UV radiation also boosts our Vitamin D and serotonin levels. This reduces the risk of several chronic and mental illnesses.
  • Too much UV radiation exposure, with insufficient protection, damages cellular DNA. This turns the cell into a zombie cell, one of the main reasons we age. Zombie cells can also turn into cancerous cells and increase the risk of skin cancer.
  • Depending on your skin type and pigment, you should spend a different amount of time in the sun. Always use sunscreen and keep an eye on the UV index to prevent sun damage but promote healthy sun exposure!
References

1 https://www.cdc.gov/niosh/emres/longhourstraining/light.html

2 https://www.skincancer.org/blog/sun-protection-and-vitamin-d/

3 https://www.hsph.harvard.edu/nutritionsource/vitamin-d/

4 https://pubmed.ncbi.nlm.nih.gov/31172459/

5 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281985/

6 https://pubmed.ncbi.nlm.nih.gov/32252338/

7 https://pubmed.ncbi.nlm.nih.gov/32945627/

8 https://academic.oup.com/ajcn/article/92/5/1017/4597479

9 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3779905/

10 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6663583/

11 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3836174/

12 https://www.nature.com/articles/nrd.2017.116

13 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4915101/

14 https://my.clevelandclinic.org/health/diseases/10985-sun-exposure-and-skin-cancer

15 https://www.ncbi.nlm.nih.gov/books/NBK321117/

16 https://www.cnn.com/2019/05/17/health/healthy-skin-diet-sunscreen-drayer-food/index.html

 

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