Friday, January 24, 2014

Why shift work is linked to so many health problems such as cancer and diabetes: Study finds it damages 1,500 genes

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http://www.dailymail.co.uk/health/article-2542780/Working-shifts-damage-1-500-genes-New-finding-explain-shift-work-associated-health-problems.html
 EMMA INNES

Shift work is thought to increase risk of cancer, heart disease and diabetes - and scientists say the finding that it damaged 1,500 genes may explain why
Shift work is thought to increase risk of cancer, heart disease and diabetes - and scientists say the finding that it damaged 1,500 genes may explain why

Shift work could damage almost 1,500 genes - explaining why it has been linked to a range of health problems, a study shows.

Disruption to the timing of sleep - also caused by jet lag - is feared to increase the risk of breast cancer, heart disease, diabetes and other life-threatening illnesses.

The researchers found disrupting the body’s natural 24 hour cycle disturbed the rhythm of genes.

To assess the effect on the body of this disruption, researchers placed 22 participants on a 28-hour day schedule without a natural light-dark cycle.

As a result their sleep-wake cycle was delayed by four hours each day until they were sleeping 12 hours out of sync with a normal day.

Blood samples showed that after this experiment the volunteers had a six-fold reduction in the number of genes that displayed a ‘circadian rhythm’ - a rhythm with an approximately 24 hour period.

Professor Derk-Jan Dijk, of the Sleep Research Centre at the University of Surrey, said: ‘We have found about six per cent of genes have a circadian rhythm - this means their activity is higher at certain times of the day than others.

One study showed night shifts triple the risk of heart disease. Mental health problems, cancer, depression, diabetes, obesity and strokes have also been linked to poor sleeping habits
One study showed night shifts triple the risk of heart disease. Mental health problems, cancer, depression, diabetes, obesity and strokes have also been linked to poor sleeping habits
‘We think those triggered mainly by day could be concerned with the immune function and those at night are involved in regulating other genes.

‘The study has important implications because we now need to discover why these rhythms exist and think about the consequences of that.

‘If we put people through these protocols we are influencing very basic processes deep down which could explain why shift work has been implicated in increasing the risk of a range of health problems.’

The human body is believed to have about 24,000 genes - suggesting more than 1,400 could be vulnerable to a change in sleeping habits. 

Professor Dijk said all the participants were in their 20s and the study was carried out in very carefully controlled lab conditions.

He said: ‘It would be nice to involve more people but you can see why this would be quite difficult. We were taking blood samples round the clock. It’s a trade-off.’

He hopes his findings, published in Proceedings of the National Academy of Sciences, will be a ‘stepping stone’ to larger studies in the future.

Professor Dijk said: ‘By disrupting sleep - and eating patterns - we are changing molecular processes by causing disturbances in the rhythm of genes.

‘This research may help us understand the negative health outcomes associated with shift work, jet lag and other conditions in which the rhythms of our genes are disrupted.

‘The results also imply sleep-wake schedules can be used to influence rhythmicity in many biological processes which may be very relevant for conditions in which our body clocks are altered such as in ageing.’

Doctors have been worried for years that our 24/7 culture could have unintended consequences for human health with more than four million people – 17 per cent of employees - in the UK now working shifts.

One study showed night shifts triple the risk of heart disease while mental health problems, cancer, depression, diabetes, obesity and strokes have also been linked to poor sleeping habits.

Study co-author Dr Simon Archer said: ‘Over 97 per cent of rhythmic genes become out of sync with mistimed sleep which really explains why we feel so bad during jet lag or if we have to work irregular shifts.’

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