– Could a good nights sleep help fight Alzheimers?

Melatonin is known as the hormone that is vital for sleep, but it may also cut your risk of cancer, help prevent Alzheimers and Parkinsons, and reduce the sagging skin and thinning hair that accompany ageing.

Melatonin works by helping to break down the bodys active and energetic hormones, slowing brain activity and allowing us to rest.

But researchers now believe the hormone – found in walnuts, grapes and porridge – could protect against the potentially harmful magnetic fields created by power cables, reduce cholesterol, boost the immune system and help children suffering from autism.

You dont hear much about melatonins bid for super hormone status in Britain because, unlike in the U.S., where it can be bought over the counter in supplement form, here, the drugs watchdog, the MHRA, has ruled it should be prescription only.

However, from this month, you will be able to buy a weaker melatonin herbal supplement.

But you may not need supplements: keeping artificial light to a minimum in the bedroom could do the trick. The hormone, made by the pineal gland in the brain, can be produced only in darkness.

Female night shift workers have low levels of melatonin and a significantly raised risk of breast cancer. So do airline stewardesses, whose rhythms of sleeping and waking are disturbed.

On the other hand, blind women, who cant see light, are 50 per cent less likely to have breast cancer.

Melatonins anti-cancer effect may be down to the fact it is a powerful antioxidant – five times more potent than vitamin C – that mops up free radicals linked to cancer.

Experts have found there is something in the blood of women who have had a good nights sleep that can slow tumour growth dramatically.

And theres mounting evidence to suggest disruption of the melatonin rhythm may also lead to chronic fatigue and depression.

Also, people who suffer from autism have half as much melatonin in their blood as the rest of the population. This may be exacerbated by their irregular sleep patterns, which prevent their bodies from making the hormone efficiently.

In most people, melatonin production peaks at 1am – being exposed to bright light after that halts its production.

People who live in towns should have heavy bedroom curtains to keep out street lights, says Professor David Henshaw, an expert on the effects of radiation on humans at the University of Bristol.

Once you pass 65, your body will be able to make only about 10 per cent of the melatonin you did when you were 30. So could this hormone help to roll back the years?

Support for the idea came earlier this year with a study at the University of Granada in Spain, which found daily melatonin supplements kept mice young.

The reason for the benefit could again be the hormones antioxidant abilities, which is why it may help reduce the severity of Alzheimers and Parkinsons – both conditions involve inflammation and free radical damage in the brain.

Until melatonin supplements are legalised in Britain, people should try to increase melatonin consumption through food and drink such as red wine, fruit, vegetables and cereals, says the lead researcher Professor Dario Acuna Castroviejo. It has recently been discovered that melatonin is present in many plants, perhaps to defend against UV light.

And it may not be a coincidence that those with the highest concentrations, such as St Johns Wort, sage and feverfew, have been used for centuries in herbal medicine.

The latest research suggests melatonin is not just active in the brain but in the gut, cornea of the eyes and immune system, where its made by white blood cells when they are dividing, and is thought to strengthen the immune response.

Melatonins role in putting you to sleep is just the start of its job, says electromagnetism expert Professor Roger Coghill, of the Coghill Research Laboratories in Wales.

As we sleep, our body is carrying out repairs on half a billion cells and to do that it needs energy. But just as power stations cause pollution, so energy production in the body pumps out damaging free radicals. Melatonin helps to mop them up.

If hes right, then not having a normal amount could cause a wide range of problems. It was his belief in the importance of melatonin that led him to develop the melatonin herbal supplement Asphalia.

It comes from the grass Festuca arundinacea, which has the highest melatonin content of any plant. So far there has been only one small controlled study, which showed it improved sleep.

But Coghill believes it could be used to protect against the effects of electric and magnetic fields (EMF) given off by power cables and possibly household electrical goods.

A government report earlier this year by the SAGE group of experts warned that EMF could cause various cancers, including childhood leukaemia, and advised against new buildings near power lines.

Theres evidence EMF can disrupt melatonin production at the same time as increasing free radical damage, says Professor Henshaw of SAGE.

Its a double whammy. You have more free radicals and less antioxidant to mop them up.

However, the National Radiological Protection Board says laboratory evidence that magnetic fields could block melatonin was inconsistent and most of the evidence from human studies argues against it.

No trials have shown that taking a supplement would make a difference to electromagnetic radiation. And the same is true for the other claims about the benefits of melatonin on cancer, ageing and brain disorders.

CancerResearch UK is sceptical about the role of melatonin, suggesting the raised risk of breast cancer in air hostesses could be due to risk factors such as having no children or having them later in life.

However, there is some evidence melatonin may be beneficial as part of a treatment regime for cancer. Researchers analysed the results of ten controlled trials involving 600 patients with cancers of the brain, breast, lung and kidneys, who had been treated with large doses of melatonin.

Overall, the risk of dying at one year was reduced by 34 per cent. But while questions remain over just how beneficial melatonin might be, there is also a dispute about its potential side-effects.

Experts such as Coghill claim it is incredibly safe, but U.S. researchers discovered recently that melatonin is involved in switching on a sex hormone in the brain that causes ovaries and testes to shrink in birds.

This shows melatonin is as powerful as any steroid, says Assistant Professor George Bentley of the University of California, Berkeley.

We just dont know what effect it has on other brain chemicals. People should be very careful when taking it as a supplement.

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