UV rays are essential if our bodies are to make the vitamin D needed to keep our bones healthy and strong. When exposed to UVB rays, skin cells produce vitamin D, a vitamin that prevents calcium and phosphorus deficiencies. Why is this so important? To prevent osteoporosis caused by bone density loss and to improve bone growth in children. 15 - 30 minutes' sunshine a day is enough to keep up your levels.

Sunshine cheers us up. When our eyes register sunshine, our brain responds by producing serotonin, a neurotransmitter that governs our mood, sleep patterns and appetite. Light therapy is recommended for anyone suffering from SAD (Seasonal Affective Disorder).In other words, sunshine makes us feel good. Having a golden glow helps, but when our happy chemicals are boosted, we're able to enjoy life's little pleasures.

Light is a powerful body clock regulator. Depending on how light it is, our eyes tell our brains what to do - wake us up, send us to sleep, alter our body temperature, produce/reduce hormones, kick-start our memory...). Sunlight sets our bodies to follow a 24hr cycle and our internal body clock works around this natural rhythm.

When light shines onto our retinas, a signal is sent to the brain, which is in turn transmitted to a small gland. When this gland realises that daylight is fading, it produces melatonin, the hormone that makes us feel sleepy. Put simply, natural light levels control how much melatonin our bodies produce. If we're exposed to bright lights at night, our bodies produce less melatonin, making it harder to fall asleep.

Doctors may recommend sunshine or artificially produced UV rays to deal with certain skin conditions including psoriasis and vitiligo. Treatments involve using light therapy. A doctor will assess how much light you need, the type of UV ray to be used and any potential risks. Treatments require a visit to a specialised clinic - sorry, girls, Balearic beaches aren't involved...; Even though basking in sunshine has it's pros, remember it can also be harmful, so make sure you always apply a sunscreen suited to your phototype and avoid going out during the hottest times of the day.