• Those with high levels of melatonin less likely to develop deadly disease

• Hormone helps regulate our sleep cycle and affects body’s 24-hour clock

• Study led by scientists at Harvard School of Public Health in Boston

Sleeping well may help to protect men from prostate cancer, scientists claim.

Those who had high levels of the sleep hormone melatonin were 75 per cent less likely to develop an advanced form of the deadly disease, a study found.

Our bodies produce melatonin when it is dark. It helps to regulate our sleep cycle and affects many functions tied to the body’s 24-hour clock, or circadian rhythm.

People with too little melatonin tend to have trouble getting to sleep and wake up in the night.

Scientists tested the melatonin levels of 928 Icelandic men, then monitored them over seven years. In that time, 111 were diagnosed with prostate cancer, including 24 who had advanced cancer.

Advanced prostate cancer that has started to spread is often aggressive and is likely to be fatal.

The researchers found men whose melatonin levels were higher than the middle of the range were 75 per cent less likely to develop advanced prostate cancer than those with levels below the middle mark.

Study leader Sarah Markt, from the Harvard School of Public Health in Boston, US, said: ‘Sleep loss and other factors can influence the amount of melatonin secretion or block it altogether.

‘Health problems associated with low melatonin, disrupted sleep, and disruption of the circadian rhythm are broad, including a potential risk factor for cancer.’

More research should be done into how melatonin affects cancer risk, she said, adding: ‘Our results require replication, but support the public health implication of the importance of maintaining a stable light-dark and sleep-wake cycle.’

Dr Matthew Hobbs, of Prostate Cancer UK, said: ‘Over 40,000 men are diagnosed with prostate cancer each year in the UK.

‘Improving our ability to distinguish which of those men are at risk of aggressive cancer that is likely to spread to other parts of the body from those with low-risk cancer is of crucial importance.

‘However, this study is a long way away from developing a test based on melatonin levels.’

A separate study of 572 prostate cancer patients found those who walked at a faster pace before being diagnosed had a better prognosis.

They had larger and more even blood vessels in their tumours, which the US researchers said can make cancer easier to treat.

It is known that physically active men with prostate cancer have a lower risk of recurrence and death, but until now scientists have not been able to explain why this should be the case.

Published at the Daily Mail, January 19, 2014.

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