The impact of sunlight on our health

As summer gets fully underway it is important to be aware of the benefits and risks of exposure to our brightest star.

The Sun, or more accurately, sunlight, has a big impact on our health, and differing levels of exposure can lead to different outcomes. In this blog we explore the impact of sunlight on our health and wellbeing.

Vitamin D:

Most essential vitamins that we can’t produce our ourselves we consume through our food. However, Vitamin D is mainly synthesized in the skin when we are exposed to UVB rays in daylight. How much Vitamin D we produce depends on several factors which impact how many rays penetrate the skin; excess body fat, clothing, sun cream and skin pigmentation will all influence the number of rays absorbed.

For most individuals (particularly Caucasians) just half an hour in the summer sun with unprotected skin will provide us with 1.25 mg of Vitamin D over the subsequent 24 hours. This is less for those with darker skin tones. Considering the UK guidelines are 10 mcg (0.01 mg) it is pretty easy to rack up our recommended daily amount by spending a small amount of time in the summer sun. In the winter this is much more challenging as there is less daylight, the sun is weaker, and we typically have more covered or protected skin.

If we don’t get enough Vitamin D this can affect bone density, risking osteoporosis in later life. Additionally, a study in 2008 pointed to evidence that Vitamin D may have a positive impact on the immune system by finding that low levels of Vitamin D were also linked with a risk of TB, which is fairly prevalent in some central London boroughs.

Serotonin and Melatonin:

When the sun goes down and daylight fades, the body increases production of melatonin which helps us to sleep. Melatonin reduces inflammation, infection and cancer risk, and is one of the reasons why sleep is so crucial to our health. Interestingly, if you are exposed to more daylight earlier in the day then melatonin production increases earlier in the evening which is linked to improved sleep.

On the other hand, more serotonin is produced with more exposure to daylight and higher levels are linked with better mood and psychological wellbeing. This is thought to be one of the reasons for the spike in negative mental health in the winter months.

Cancer Risk:

Whilst on the whole sunlight exposure is generally good for us, there can be too much of a good thing. Skin cancer is one of the most common form of cancers worldwide, particularly in countries with higher daylight hours across the year.
Skin cancer risk is increased with increased exposure (unprotected) to UVR rays which can cause mutations in skin cells. However, conversely, getting the adequate Vitamin D from sunlight can actually reduce the risk of many other cancers by between 50-77% depending on the studies you follow, so there is a balance to be struck.

Other effects:

There is some evidence that adequate levels of Vitamin D may reduce the risks of multiple sclerosis and Type 1 Diabetes, and there are lots of other less well studied links between the protective effects of sunlight and a reduction in hypertension, metabolic disease and others. However more research is needed.

Getting the balance right:

Overall, well balanced sunlight exposure is very good for us and can improve our health by:

  • Improving sleep
  • Reducing inflammation and stress
  • Reducing chronic disease risk
  • Improving psychological health
  • Maintaining bone health

However too much, or not enough protection can be detrimental to our health. The key guidelines to safe exposure are:

  • Use the early morning and late afternoons when the sun is at its weakest as the key times to be in the sun
  • Use clothing to protect skin exposed for more than 30 minutes, especially between 10 am and 2 pm.
  • Use a sunscreen of SPF 15 or higher throughout the day in the summer months, reapplying every 2-3 hours
  • Stay well hydrated!
  • Use sunglasses to protect your eyes

 

Words of wisdom:

“Shadows cannot see themselves in the mirror of the sun” – Eva Perón