- The Danish scientist and heliotherapist Niels Ryberg Finsen realised that the sun had an important impact on his health after seeing how cats were attracted to lying in the sun. In 1903 he won the Nobel Prize for light-therapy work. Soon after, 36 heliotherapy centres were opened in the Alps and soon after having a tan became fashionable. So, a walk in the sunshine is good for us!
- Nowadays, as we spend most of our time indoors, up to 70% of people are believed to have a vitamin D deficiency. It is created when UVB rays hit our skin and goes to our liver and then to our kidneys to become a hormone called calcidiol 25(OH)D3, and lasts up to 3 weeks. So, our bodies need constant sunshine to keep our serum levels stable. It’s recommended to have between five and 30 minutes of light on your face, neck and arms every day depending on your skin type and UV index.
- It was noticed during Covid that low levels of vitamin D were linked to poorer recovery and that it is needed for good functioning of our innate immune system, the defense system which allows us to deal with germs, allergens and fends off many viruses. Whereas, our acquired immunity system develops as we’re exposed to pathogens, triggering the production of antibodies (making vaccines work).
- A deficiency of sunshine (not vitamin D) has also been linked to heart disease, hypertension, osteoporosis, several cancers, depression, dementia and multiple autoimmune diseases. A Swedish study found that a lack of sunlight could be as dangerous as smoking.
- Researchers believe that photons from sunlight activate our T-cells, vital components of our immune system, by mobilising nitric oxide from our skin and transferring it to our circulatory system. Our skin carries twice as many T-cells as our blood. The blue light in sunshine reaches the surface of our skin and the dermis underneath, enabling rapid activation of the T-cells there.
- Sunlight also has an important role in setting our circadian rhythms and moderating our production of melatonin, helping us to wake and sleep.
- So, sunshine has important effects unrelated to vitamin D, suggesting that taking supplements as a substitute isn’t enough. However, scientists continue to debate how far to depend on just one or the other. One suggestion is to take short walks with your face, neck and arms exposed without sunscreen, building up with gradually longer exposure. British heliotherapist, Henry Gauvin, said sunlight is ‘like a good champagne. It invigorates and stimulates; indulged in to excess, it intoxicates and poisons.’
- So, let’s go for a short walk in the sunshine, as it also triggers the feel-good hormone, serotonin, making us feel better!
- Fuente: 52 maneras de caminar: Annabel Streets – Bloomsbury Publishing