UV rays and your body 
There is a great debate going on at the moment about the role of UV light in our wellbeing.
Certainly it is possible to get too little sun, especially by the elderly and those who spend their outdoor lives in a full body covering. We know this can lead to deficiencies particularly in Vitamin D which in turn can lead to bone problems and yes lower resistance to cancers.
Equally certainly, it is possible to get too much sun which often leads to headaches, can lead to sunburn and to a variety of skin problems. Most modern thinkers agree that it is much easier for most people to get too much sun than too little!
One little realised but fairly obvious theory relates to the role our eyes play in all this. The hormone (MSH) that stimulates tanning is produced by the pitutary gland which has links to the eyes. The amount of UV light falling in your eyes determines the amount of MSH released and so the level of activity of your melanin producing glands - your natural tanning. If you cover your eyes with shades then that fools the body into thinking the levels of UV light falling on you are low! So if you want to tan then every five minutes or so, take off your sunglasses for thirty seconds!
If you do get sunburn you are actually getting a long term problem. Not only does sunburn take hours to come out fully, which is why it may actually feel worse days after you got it, but there is evidence of links between sunburn and DNA damage.
There is also a strong link between sunburn in childhood and skin cancers later - but not in everybody!
There is evidence that many patients with non skin-related problems, including cancers, benefit medically from exposure to sunshine. But again how much and when is debated.
It is becoming very clear that the levels of sun exposure which lead to both benefits and dangers are very variable, almost individual. In other words, what is of benefit to your darker skinned neighbour could easily be dangerous for your lighter skin self.
The difference between Suntan and Sunburn
- Suntan
- The opportunity for the skin to adjust (pigment) - positive psychological benefits in many people, but frankly, not many medical benefits. Benefiting from the rays of the sun and tanning should not be confused.
- Sunburn
- The skin's defense mechanisms are overwhelmed - never a good idea.
Types of sun barriers
The American Academy of Dermatology recommends as a minimum:
- 4" (10cm) brim hat,
- Sunglasses,
- Physical or chemical block applied to the skin.
What is the difference between a physical and chemical block?
A physical block sits on the skin's surface.
This could be an item of clothing (like a close woven T shirt) or a sun cream or lotion.
If you are choosing clothing then go for a close weave in a dark colour. It turns out that thickness, weight or material does not make much difference, it is the closeness of the weave that is key to keeping out UV rays.
Typical components of sunscreen providing a physical block are Titanium Dioxide and Zinc Oxide - either can often leave a white film on your skin. This type of sun protection cream or lotion is absorbed only into the top layer of the skin. Light falling on the skin is either absorbed into the sunblock material or reflected away from the body back into the atmosphere in a similar way that a coating of mirrors would do.
Titanium Dioxide and Zinc Oxide are generally regarded as being non-irritating but are quite expensive so they tend to be reserved for special small areas of the skin that are particularly vulnerable like the back of the neck, nose, ears, arms and hands. Be careful to check that the formulation protects against both UVA and UVB radiation although these should be OK.
A chemical block has the ability to be absorbed more deeply into the skin.
When sunlight falls on this sort of protection then the energy is soaked up by the chemicals. This is why these chemicals need to be regularly replaced. Such chemicals often come with long names and the cream completely disappears when rubbed into the skin. With these sunscreens it is especially important to be careful that they protect against both UVA and UVB radiation - "broad spectrum" is the term to look out for.
Whenever you are using a new chemical ingredient in a sunscreen, it is a good idea to check for an allergic reaction by trying some on a small patch of skin first.
