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As I currently make my way through researching a new module in my Circadian Retraining Program, I’ve come across a pretty interesting review on the benefits of Sun exposure.  The review backs up one side of a ping pong contest between health authorities trying to balance the benefits of Sun exposure with the increased risk of skin cancer.

Many health authorities, incorrectly so, believe that vitamin D supplementation is a workable solution to this problem.  Unfortunately, a lot of the data with vitamin D supplementation is conflicting, leading to doubt as to whether or not we need to worry about getting Vitamin D levels in to an adequate range.

Perhaps the conflicting evidence with vitamin D hinges on using supplements to boost vitamin D levels instead of UV exposure.  Measuring vitamin D levels functions not only as a means of determining how much vitamin D you make, it also acts as a biomarker of sun exposure.  And the benefits of Sun exposure go far beyond the effects UV radiation has on the production of vitamin D.

Yes we need adequate vitamin D levels, but there are other benefits of getting Sun exposure that vitamin D supplements don’t compensate for.  Based on my research I’ve come to this conclusion.

To make matters worse, my research has led me to the conclusion that UV exposure directly to the skin causes many of the physiological health benefits and helps set the circadian rhythm.  In other words, using sunscreens to block UV rays has risks associated with it that may interfere with peripheral clocks, particularly in the skin.

But that doesn’t remove the risks associated with too much UV exposure.  Thus, an intelligently and logically laid out plan is necessary to optimize UV exposure.

Benefits of Sun exposure

The review covers some of the non-vitamin D mediated benefits of Sun exposure on the skin.  This includes:

1. Colorectal cancer(CRC)-Sun exposure AND vitamin D lower colorectal tumor surface area in mice but only sun exposure led to a decrease in the percentage of tumors that turned malignant.  In humans, supplemental D had no effect on CRC risk but those with blood levels >40ng/mL had a 42% reduced risk of CRC compared to those with levels <10ng/mL.
2. Breast cancer-Women with the highest UVB exposure had half the risk of breast cancer than those with the lowest.  Vitamin D studies are conflicting and inconclusive.
3. Prostate cancer-Sun exposure but not vitamin D status is protective against prostate cancer.
4. Lymphoma/Non-Hodgkins lymphoma-Sun exposure but not vitamin D status is protective against lymphoma and non-Hodgkins lymphoma.
5. Cardiovascular disease(CVD) and obesity-The benefits of Sun exposure on CVD risk don’t appear to come from vitamin D.  The primary protection may coome from the generation of nitric oxide in the skin, which lowers blood pressure.
6. Multiple Sclerosis(MS)/Type 1 diabetes(T1D)/Arthritis-Sun exposure lowers the risk of MS, T1D, and arthritis through vitamin D independent processes.
7. Liver disease-Vitamin D levels are inversely associated with NAFLD, but supplementation doesn’t provide full protection, indicating vitamin D independent processes also being involved.

The review is quite interesting and based on what I’m putting together for the program, sun exposure to the skin is a factor people need to start paying attention to, both magnitude and timing.  You can check it out here.

Based on my research, skin exposure to the Sun may also play a role in increasing REM sleep.  I should point out, again, that you need to address this in an intelligent way.  Especially if you’re fair-skinned, work in an office, or in an area where UV radiation is absent for portions of the year, like the East coast of the US.  But I truly believe that blindly avoiding the Sun is something that will have a negative impact on your health.