Scientists uncover more benefits of sun exposure

Whenever I spend time in the yard in the early morning, I close my eyes and lift my face to the sun. The warmth spreads through me, and I can feel the stress of facing another day leave my body. In Ayurveda, it is called the morning “sun salute.” Maybe you too feel this way when you spend time relaxing in the sun.

Well, now we know there’s a scientific explanation for this physical sensation. Turns out, sun exposure helps improve blood flow throughout your body. And it even reduces blood pressure. I’ll explain more about that incredible process in a moment, but first let’s back up…

As you know, sun exposure activates your skin’s production of vitamin D. Of course, this critical nutrient helps ward against depression, dementia, Type II diabetes, heart disease, and metabolic and neurological conditions. Vitamin D also lowers the risk of cancers, including skin cancer. In fact, as I reported last week, in a new study, researchers followed men and women with malignant melanoma, the one truly deadly form of skin cancer. They found men and women with low vitamin D levels had thicker tumors, a key measure of melanoma’s aggressiveness and danger.

So back to the relaxation benefits of sun exposure…

Scientists know blood pressure is commonly higher in winter months, when people have less sun exposure. We also know spending time in Nature has a positive “mind-body” effect in terms of easing stress. But we never had the all-important “mechanism of action” to explain how sun exposure eases stress and lowers blood pressure physiologically.

Remember, modern scientists can’t just accept that a treatment works. They need to know why and how it works. We call this a treatment’s “mechanism of action.”

Fortunately, British researchers recently followed the clues, like Sherlock Holmes, the quintessential British sleuth created by physician turned author Sir Arthur Conan Doyle. And they found the all-important “mechanism of action.”

To start, researchers exposed 24 healthy volunteers to ultraviolet A radiation for 30 minutes with an intensity comparable to a sunny day at noon in Southern Europe. The exposure caused a small but significant drop in the volunteers’ blood pressure. By comparison, men and women exposed to placebo UVA radiation (the same amount of heat and light, but no UVA exposure) experienced no drop in blood pressure.

The researchers also gave the volunteers blood tests before and after UVA exposure.

Turns out the real UVA exposure triggered the skin to release its stores of nitric oxide into the bloodstream.

Nitric oxide is a powerful chemical that causes the blood vessels to dilate and reduces resistance in blood vessels. Ultimately, it lowers blood pressure through simple fluid dynamics.

Nitric oxide also acts in the brain stem to reduce sympathetic stimulation, which reduces adrenalin and lowers blood pressure.

That’s one reason why doctors give nitroglycerin as a fast, effective treatment for angina pectoris. It releases nitric oxide, which again, dilates the blood vessels that supply the heart. This action supplies more blood and oxygen to the starving heart muscle tissue.

So now–we know exactly how and why sun exposure can lower stress and blood pressure. Therefore, we should begin to look at sun exposure as a way to help manage blood pressure naturally.

Of course, as I recently explained, sunscreen blocks the UV rays that activate vitamin D. It also blocks mobilization of nitric oxide to reduce blood pressure. Plus, recent reports show 80 percent of sunscreen products contain harmful ingredients and/or overstate their level of protection.

But clearly we need some sun for good health. In fact, in the later 19th century, doctors often prescribed seaside holidays to their patients for a variety of health problems.

Fortunately, you don’t need to wait for your doctor to give you the okay for some healthy sun exposure. Go ahead and spend 15 minutes in the sun every day without sunscreen. And take note of how relaxed your body feels.

We’ve just passed the summer solstice, so it’s really the perfect time to soak up some rays.


“UVA Irradiation of Human Skin Vasodilates Arterial Vasculature and Lowers Blood Pressure Independently of Nitric Oxide Synthase,” Journal of Investigative Dermatology (2014) 134, 1839–1846