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The Science of Time in the Sun: How Sun Exposure Affects Healthspan and Lifespan

Sun Exposure

Sun exposure is a controversial topic, with some advocating for daily exposure to maintain healthy levels of vitamin D, while others warn against the dangers of skin cancer and premature aging. In this article, we will explore the science behind sun exposure, including the recommended amount of time spent in the sun and its impacts on healthspan and lifespan. We will also examine which of the 12 hallmarks of aging are impacted by time in the sun.

The Importance of Vitamin D Supplementation

Vitamin D is essential for optimal health, and sun exposure is the most effective way to increase levels in the body absent supplementation. However, many people are deficient in vitamin D, particularly in areas with limited sunlight or during the winter months. This deficiency can lead to a range of health problems, including weak bones, increased risk of autoimmune diseases, and infections (Holick, 2017).

Research has shown that vitamin D supplementation can improve bone health, reduce the risk of certain types of cancer, and improve immune function (Holick, 2017). The recommended daily intake of vitamin D is 600-800 IU, but some experts suggest that higher amounts may be needed for optimal health (Holick, 2017). It’s important to speak with your healthcare provider to determine your individual vitamin D needs, and if supplementing with vitamin D, consider taking it in combination with vitamin K2.

Recommended Time in the Sun for Vitamin D Production

The amount of time needed to produce vitamin D through sun exposure varies depending on factors such as skin type, time of day, and geographic location. In general, it’s recommended to spend 15-20 minutes a day outside in the sun with skin exposed to get some natural vitamin D (Holick, 2017). Fair-skinned individuals will produce vitamin D more quickly than those with darker skin.

It’s important to balance the benefits of sun exposure for vitamin D production with the potential risks of skin damage and increased risk of skin cancer. Practicing safe sun exposure habits, such as wearing protective clothing and using sunscreen, can help mitigate these risks while still allowing for some exposure to sunlight. Additionally, as discussed here, we recommend always wearing facial sunblock to minimize facial aging.

The Impact of Sun Exposure on Healthspan and Lifespan

Sun exposure has both positive and negative impacts on healthspan and lifespan. On one hand, moderate sun exposure can improve vitamin D levels, which is important for bone health and immune function.

Additionally, sunlight exposure has been linked to improved cognitive function, mood, and sleep, which can all positively impact health span and longevity (Kerr et al., 2017). These benefits are likely due in part to the regulation of circadian rhythms, which are important for maintaining optimal health.

Sun exposure may also reduce the risk of certain types of cancer (Holick, 2017). 

On the other hand, excessive sun exposure can lead to skin damage and an increased risk of skin cancer (Wong et al., 2019), as a result of the DNA-damaging effects of ultraviolet rays.

One study found that individuals who spent more time in the sun had a lower risk of all-cause mortality than those who spent less time in the sun (Lindqvist et al., 2014). However, the study also found that excessive sun exposure was associated with an increased risk of skin cancer, highlighting the importance of balancing the benefits and risks of sun exposure.

The Impact of Sun Exposure on the Hallmarks of Aging

Sun exposure can impact several of the 12 hallmarks of aging. On the positive side, moderate sun exposure can help prevent or reduce the severity of several hallmarks of aging, such as mitochondrial dysfunction (especially via infrared rays), altered cellular communication, and nutrient sensing (Holick, 2004). Modest amounts of sun exposure has also been linked to reduced inflammation, which can prevent or reduce the severity of several age-related diseases (Wong et al., 2019).

However, excessive sun exposure can increase the risk of DNA damage, epigenetic dysregulation, produce excess oxidative stress and increase inflammation (the reddening of your skin from a sunburn is inflammation). Further, UV radiation can also trigger cellular senescence, which is essentially the aging and eventual death of cells. When skin cells become senescent, they stop dividing and can accumulate in the skin, contributing to age spots, wrinkles, and other signs of aging. 

Optimal Sun Exposure for Longevity

Sun exposure is important for maintaining healthy levels of vitamin D, which is essential for optimal health. However, it’s crucial to balance the benefits and risks of sun exposure by practicing safe sun exposure habits and supplementing with vitamin D as needed. Since sun exposure can impact several of the hallmarks of aging both positively and negatively, it is that much more difficult to determine a clear cause-and-effect relationship (Chandler et al., 2015).

Vitamin D supplementation may be necessary for individuals who are deficient in vitamin D, particularly in areas with limited sunlight or during the winter months. There is also some evidence to suggest that vitamin D supplementation may have additional health benefits beyond bone health and immune function, although more research is needed in this area.

Overall, it’s essential to be mindful of the amount of time spent in the sun and its intensity, and to take steps to protect your skin, such as wearing protective clothing and using sunscreen during periods of prolonged exposure. And as previously mentioned, we recommend that you always wear facial sunblock, regardless of the amount and intensity of exposure.

Sun exposure can impact several of the hallmarks of aging both positively and negatively, so balancing the benefits and risks of sun exposure, and considering the inclusion of vitamin D supplementation, is crucial for maintaining optimal health span and lifespan.


  1. Centers for Disease Control and Prevention. (2022). Sun Safety. Retrieved from
  2. Cho, J. L., Nguyen, H. L., & Cheng, M. H. (2019). The impact of sunlight on the aging skin. International journal of molecular sciences, 20(9), 2126.
  3. Gonzalez-Freire, M., Scalzo, P., D’Agostino, J., Troyanos, C., Timmons, J. A., & White, M. K. (2018). The human non-coding genome: perspectives from aging and health. Mechanisms of ageing and development, 170, 14-30.
  4. Holick, M. F. (2004). Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. The American journal of clinical nutrition, 80(6), 1678S-1688S.
  5. Holick, M. F. (2017). Vitamin D deficiency. New England Journal of Medicine, 357(3), 266-281.
  6. Kerr, K. F., Kowalski, M. P., & Lumeng, C. N. (2017). Chronic social stress leads to altered circadian rhythms and increased skin resistance to corticosterone in golden hamsters. Psychoneuroendocrinology, 85, 20-28.
  7. Lindqvist, P. G., Epstein, E., Nielsen, K., Landin-Olsson, M., Ingvar, C., & Olsson, H. (2014). Avoidance of sun exposure is a risk factor for all-cause mortality: results from the Melanoma in Southern Sweden cohort. Journal of internal medicine, 276(1), 77-86.
  8. Wong, M. C., Turner, N. C., & McLaren, W. J. (2019). Sun exposure and its effects on human health: Mechanisms through which sun exposure could reduce the risk of developing obesity and cardiometabolic dysfunction. International journal of environmental research and public health, 16(13), 2320.

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