How erratic work schedules impact your health

Shift work, night work, changing routines — all of them come at a huge cost to your health and fertility, writes Dan Buckley.

BEING paid extra for working the ‘graveyard’ shift may help pay the bills — but it comes at huge cost to your health, an increasing body of research shows.

Erratic work schedules that disturb a person’s body clock — known as the circadian rhythm — can increase the risk of contracting deadly diseases like cancer and diabetes.

The latest study to add to the growing evidence of serious health implications finds that working overnight or different shifts is associated with a higher risk for type 2 diabetes.

The highest risk was linked to rotating shifts, where different parts of a 24-hour shift cycle are worked, rather than a fixed pattern.

In their analysis, published in the British Medical Journal, researchers found that working rotating shifts, rather than consistent work hours, was associated with a 42% increased risk for type 2 diabetes. Overall, they concluded that people working unconventional schedules may increase the risk of developing type 2 diabetes by an average of 9%. For men, that risk increases to 37%.

“Some potential biological mechanisms may explain the link between shift work and diabetes,” the researchers write in their study.

“First, shift work may interfere with the normal synchrony of the light/dark cycle, sleeping and eating patterns, which might cause a mismatch of circadian rhythms.”

The researchers say shift work may put men at greater risk of diabetes because levels of the male sex hormone, testosterone, are controlled by the body’s natural circadian rhythm. Lower testosterone can cause insulin resistance and therefore raise the risk of the disease.

“The result suggests that male shift workers should pay more attention to the prevention of diabetes,” say the researchers. “Rotating shifts are especially detrimental to one’s health because inconsistent work schedules also mean erratic sleep and therefore an inconsistent sleep-wake cycle, which is associated with insulin resistance.”

The meta-analysis is based on data from 12 previously published studies involving more than 226,600 adults. Among that number, 14,600 study participants were confirmed to have type 2 diabetes.

Other studies have linked shift work to a number of other serious health problems.

Last year, researchers in Canada found that women who work nights for more than 30 years may be at a higher risk of breast cancer than other women.

The study, also published in the British Medical Journal, analysed the careers of 1,134 women with breast cancer and 1,179 women without the disease. Late night and rotating shift work can have a serious impact on women’s health, particularly her fertility. A study last year, involving 119,000 women, found female shift workers had a 22% greater risk for menstrual problems and as much as 80% higher risk for low fertility than women who kept normal work hours.

Expectant mothers who worked at night also experienced higher rates of miscarriages, researchers at the University of Southampton found.

In a 2012 study, men who work nights were found to be almost three times more likely to develop prostate cancer than those who do day shifts. They are also at much greater risk of a number of other types of cancer, with higher rates of tumours in the bowel, bladder and lungs.

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