Into the Blue (and Beyond)

Ultraviolet (UV) light is a type of electromagnetic radiation that is invisible to the human eye. It is present in sunlight and is responsible for the tanning of the skin and the production of vitamin D in the body.? UV Light has a relatively short wavelength ranging from 100nm (UVC) to 400nm (UVA).? If we consider the light related part of the electromagnetic spectrum - Ultraviolet, Visible, & Infrared Light - Ultraviolet accounts for 7% by comparison to Visible Light at 39% and Infrared Light at 54%.

Whilst there are benefits to exposure to UV Light, there are also have harmful effects on the skin and eyes and this must be taken into consideration and it important to take a sensible approach to UV Light exposure.

UV light is divided into three types: UVA, UVB, and UVC. UVA penetrates the skin and is responsible for premature aging and skin damage. UVB is responsible for sunburn and can also contribute to skin cancer. UVC is the most harmful type of UV radiation, but it is mostly absorbed by the Earth's atmosphere and does not reach the surface.

Despite the risks associated with UV light there are also benefits and these include...

1.? Vitamin D production: UVB radiation from the sun helps the body produce vitamin D, which is essential for healthy bones and teeth as well as brain health.

2.? Mood regulation: Exposure to sunlight, including UV light, can boost serotonin levels in the brain, improving mood and reducing symptoms of depression.

3.? Skin conditions: UV light can be used in the treatment of certain skin conditions such as psoriasis, eczema, and vitiligo.

4.? Sleep regulation: Exposure to natural sunlight, including UV light, can help regulate the body's circadian rhythm, promoting healthy sleep patterns.

I've been particularly interested in Ultraviolet light's role in the production of vitamin D in the body.? Vitamin D is a critical component for general physical health and wellbeing as well as for good brain health.? It has been established that almost?one billion people worldwide have low levels of vitamin D and approximately 20% of the population in the UK have a vitamin D deficiency, 60% of the population are considered as having insufficient levels of vitamin D.? In a world where the average person is spending 90% of their time indoors is it any surprise that we are seeing such high numbers of vitamin D insufficiency and deficiency, and maybe it is a contributing factor to the rise in major illnesses?? It has been reported that in 2040 in the UK nearly one in five will have health conditions such as dementia and cancer, up from one in six in 2019.? Research conducted in France found that individuals exhibiting vitamin D levels below 50 nmol/L were nearly three times more likely to develop Alzheimer's disease.? Our connection to the natural world is slowly being eroded and at the same time and maybe consequently our physical and mental health and wellbeing is also deteriorating over time.

When the skin is exposed to UVB radiation from the sun, a type of cholesterol in the skin called 7-dehydrocholesterol is converted into vitamin D3 (cholecalciferol). Vitamin D3 is then transported to the liver and kidneys where it is converted into the active form of vitamin D that the body can use.

The amount of UV exposure needed for vitamin D synthesis can vary depending on several factors, such as skin type, age, geographic location, and time of day. It's recommended that people get 10-30 minutes of midday sun exposure several times per week, without sunscreen, to maintain healthy levels of vitamin D. However, people with darker skin, those living in northern latitudes, and those who spend most of their time indoors may require more sun exposure or vitamin D supplementation to meet their needs.

The image below is a sunshine calendar depicting which months you can get vitamin D from the sun depending on where you live.

From this sunshine calendar and being based in the UK, for at least 4 months in the year I am not able to naturally synthesise Vitamin D as the sun is too low in the sky.? As UV light is a short wavelength light it struggles to reach the earth when the angle of the sun is low.? In March, April, May, September, and October it is possible to synthesise vitamin D, and it is likely to take me approximately 30 minutes to produce a sufficient level of Vitamin D.? In June, July and August I will need approximately 20 minutes.

As mentioned above our synthesis of Vitamin D differs with our skin tone, people with a light skin tone will produce Vitamin D faster than people with darker skin tones.

If, on average, we spend 10% of our time outdoors (not all of it will be in daylight, and for those people in North America it's worse as they apparently only spend 7% of their time outdoors according to research), then the maximum time we are outdoors is 2.4 hours a day, yet it can take someone with a darker skin tone up to 90 minutes or 1.5 hours to synthesise Vitamin D effectively.? In the UK in January, February, November, and December no amount of time outside will allow us to produce Vitamin D and so without some element of supplementation our reserves of Vitamin D will be depleted during this period.? Maybe this depletion of Vitamin D has something connection with why we might feel a bit down or low in January or February in the northern hemisphere.? Vitamin D sufficiency is strongly connected with good brain health, and the opposite is also true when one is Vitamin D deficient.

Once we do get to the warmer and longer days of the spring and summer months, we aren't necessarily able to synthesise Vitamin D naturally at all hours of daylight, there is another variable, and it is that the UV Index needs to be 3 or above.? If you happen to own a smart watch, you should be able to have a UV Index reading available to you on your home screen.? Some weather apps for smart devices will also show the UV Index.? Last year the first time I noticed the UV Index getting to 3 or more was 1st April (2023).

Not only is the UV index a determining factor for the synthesis of Vitamin D, the angle of the sun also has an impact.? The shadow rule is a simple gauge to help anyone understand if they are producing Vitamin D.? The rule is that if your shadow is longer than you are tall then you will not be producing Vitamin D...

As with everything these days there are apps for monitoring our Vitamin D production.? One app is DMinder (https://dminder.ontometrics.com ).? Ontometrics describes D-Minder as follows - D-Minder tracks Vitamin D from the sun. The sun is by far the best source of Vitamin D, and dminder allows you to optimise levels based on your location, body type, and time of day, all while making sure you stay safe by warning you of any risk to your skin getting burned. - D-Minder was developed by Ontometrics and Michael F. Holick one of the world's leading experts in the field of Vitamin D.

I started using the app in April 2023 and since then I have been actively tracking my estimated levels which were relatively low to start off with and then grew over time.? I have to admit that I do also supplement my natural Vitamin D levels even through the summer as I am no different to the average person and I spend more time indoors than I probably should.

More recently I had to have a blood test and I took the opportunity to ask my doctor if I could get my blood level Vitamin D information as part of the results, he kindly obliged and was very pleased to see that my Vitamin D level was where I would want it to be, well within the sufficiency window.

It's also important to note that other factors can affect vitamin D synthesis, such as air pollution, cloud cover, and the use of sunscreen. Using sunscreen can block UVB radiation and reduce vitamin D synthesis, but it's still important to use sunscreen to protect the skin from harmful UV rays.? Age also has an impact, as our skin ages our ability to produce Vitamin D decreases.

I'm conscious that this was supposed to be about Ultraviolet light and it has progressed into a post about Vitamin D, and of course the two are intrinsically connected, however in the same way as I think we take light for granted I feel that we ignore all the amazing things that happen when we are exposed to light, natural light being the really good stuff!? Vitamin D has a profound impact on our health and wellbeing and has a positive impact on our bone health (Vitamin D sufficiency is essential for the transportation of Calcium to our bones), our brains need Vitamin D to function well, and research suggests that Vitamin D can help protect us against certain types of Cancer.?

When we synthesise Vitamin D naturally through exposure to UV Light it stays in our body three times longer than supplemented Vitamin D, it is a truly fascinating component to our health that should not be ignored.? If you want to know more about Vitamin D then I can recommend Dr Michael F Holick's book - The Vitamin D Solution - it is an eye opening read.

Of course if you have concerns about your vitamin D levels, you should talk to your doctor about getting tested and about potentially taking vitamin D supplements.

We must always remember that too much exposure to UV light can have harmful effects on the skin and eyes. Sunburn and skin damage can increase the risk of skin cancer, and chronic exposure to UV radiation can cause premature aging and wrinkles. UV light can also damage the eyes, causing cataracts and other eye diseases.

To protect against the harmful effects of UV light, it is important to wear protective clothing and sunscreen when spending extended time outdoors, especially during peak UV hours. It is also important to wear sunglasses that provide UV protection to protect the eyes.

As with anything in life it is important to find the right balance, not living to excess nor becoming a UV hermit, so that we can produce adequate amounts of vitamin D safely and protecting the skin from excessive UV exposure.

Just because we can't see it, don't ignore it.? UV can be an enormous power for good, and at the same time we must tread carefully as too much of a good thing can be detrimental in excess!