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Nightshift: Alterations in sleep patterns could suppress the production of melatonin
The Danish government has begun paying compensation to women who have developed breast cancer after long spells working nights.

It follows a ruling by a United Nations agency that night shifts probably increase the risk of developing cancer.

BBC Radio Scotland's The Investigation has been hearing from experts and union leaders in Scotland who said the UK government should be doing more to tackle the dangers.

For years there has been growing evidence that night shifts are bad for you.

Among the symptoms: disturbed sleep, fatigue, digestive problems and a greater risk of accidents at work.

But these are the first government payments to women who have developed breast cancer after long spells on the night shift.

Ulla Mahnkopf is one of those who has been compensated.

Long hours

She spent 30 years as a flight attendant for the big Scandinavian airline SAS.

Long hours and disturbed working patterns came with the territory.

Then she developed breast cancer.

"It was awful telling my kids that, telling them what we were facing," she told me.

"It's not just the surgery but all the thoughts - do I survive this? I had bilateral cancer so not just one breast, two breasts."

At first she did not make the connection between her cancer and night working.

She said: "I had no idea.

"But when you think back now I can see that when I stopped flying it was like coming out of a shell, I had been living in there because of jet lag and I can see now I had a totally different life."

So far almost 40 Danish women have won compensation.

Not every case was successful: women who had a family history of breast cancer were among the ones whose claims were rejected.

The Danish authorities acted following a finding by the International Agency for Research on Cancer (IARC), an arm of the UN's World Health Organisation.

The IARC studies and ranks cancer risks.

Category One risks are known carcinogens such as asbestos. Night working now sits just one rung below that: a probable cause of cancer.

Dr Vincent Cogliano of the IARC said they reached their conclusion after looking at a wide number of studies of both humans and animals.

He said there was evidence to support the hypothesis that alterations in sleep patterns could suppress the production of melatonin in the body.

"Melatonin has some beneficial effects in preventing some of the steps leading to cancer," he said.

"The level of evidence is really no different than it might be for an industrial chemical."

Here in the UK unions estimate about 20% of the national workforce is involved in night shifts.

night shift worker - police control room
Alterations in sleep patterns could suppress the production of melatonin

Professor Andrew Watterson, an occupational health specialist at Stirling University, said we are far behind Scandinavia in recognising the dangers.

"I think we can say there is a big public health problem here," he said.

"The evidence has been good over a long period of time about cardiovascular disease and night work, gastro-intestinal problems and nights.

"Work indicates there may be risks in terms of low birth-weight babies and longer pregnancies for women.

"We don't tend to identify the damage being done where shift working is prevalent and I think that's an error. The damage is there but we don't see it and we don't count it."

At the Health and Safety Executive, chief medical officer Dr John Osmond said they were aware of the debate and have commissioned their own research.

"The HSE has been very on the ball in this area and has commissioned a very eminent epidemiologist to examine the risk of working at night and whether there is any link to breast cancer. This report will be completed in 2011."

But assistant general secretary of the Scottish TUC, Ian Tasker, thinks the UK is lagging behind.

He fears workers may be missing out on health checks to which they are entitled under the existing law.

Greater awareness

"I don't think we have enough evidence to say they're not," he said.

"But we have a feeling that perhaps employers are taking the opportunity to ensure these health checks are not carried out or, if they are, it's very much a tick-box approach to it."

In the meantime unions are calling for a greater awareness of the dangers of night shifts.

But for some workers, such as Ulla Mahnkopf, that is already too late.

She said she would have given up her job if she had known the dangers.

"I wouldn't have been flying for that many years, definitely not. Because it's cancer you can die from. So I would like to stay alive."

The Investigation is on BBC Radio Scotland at 0900 GMT on Monday.