The Doctor's notebook | Action Medical Research

Touching Lives - July 2008

The Doctor's notebook

Why is it so dangerous to spend too much time in the sun? We’re all aware of the risk of developing skin cancer, which is a real risk and should be taken seriously, but overexposure to the sun can have more immediate effects on our health too. Heat exhaustion and heat stroke can come on very suddenly after too long in the sun, and can have serious consequences if untreated. Another effect can be an allergic reaction in the form of red, itchy patches on the skin, called polymorphic light eruption. And a lesser-known consequence is an increased risk of developing cataracts.

What precautions should we take? The basic rule for avoiding ill effects from the sun is not to let yourself get burnt. Avoid being out in the full sun between 11am and 3pm — generally the hottest part of the day. Cover up in a t-shirt, hat, sunglasses with UV protection and, of course, use a sun cream — of at least factor 15. It’s also very important for parents to ensure that children are fully protected, and that babies under six months old are kept out of direct sun completely.

What are the signs of heat exhaustion or heat stroke? Heat exhaustion can cause headaches, dizziness, nausea and vomiting, muscle weakness or cramps, pale skin, and a high temperature. Heat stroke can result from untreated heat exhaustion, or come on suddenly without warning. They share many symptoms, but someone with heat stroke could also suffer an intense thirst, sleepiness, hot, red and dry skin, a sudden rise in temperature, confusion, aggression, convulsions and even loss of consciousness.

What should you do? If you suspect that you or someone you are with may have heat stroke, move them to a cool place, and increase the ventilation by opening windows and switching on fans. Loosen their clothes and sprinkle them with cool water to reduce their temperature as quickly as possible, and make sure they keep hydrated. In the event of unconsciousness, you should call the emergency services.

What are the latest figures regarding skin cancer and the sun? Skin cancer is the most commonly diagnosed cancer in the UK. The statistics are usually looked at under two categories — one is non-melanoma skin cancer (NMSC) which is the most common type of skin cancer, and most easily treated of all cancers. It tends to affect people in areas where the skin is often exposed such as the head, neck, forearms and hands. Figures show that in 2004, 72,000 cases of NMSC were registered in the UK. Malignant melanoma is more serious, but far less common, with around 8,000 people in the UK diagnosed each year. Although malignant melanoma makes up only 11 per cent of skin cancer cases, it is responsible for around 80 per cent of skin cancer deaths. Overall, around 80 per cent of melanomas are due to exposure to sunlight.

So, are there any benefits to spending time in the sun? Yes, there are, not least of which is the fact that it can make us feel happier! Sunlight stimulates the pineal gland in the brain, which produces chemicals called ‘tryptamines’ that improve our mood. Also, ultraviolet light from the sun is our main source of vitamin D, good for our bones, muscles and immune system, and, ironically, may also help combat the development and spread of cancerous tumours. You don’t have to stay out of the sun altogether — but be sensible and take the recommended precautions to enjoy the sun safely.

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