US study identifies health concerns for shift workers

A 14-year study conducted by Chronobiology International on more than 7000 subjects in the US on how biological rhythms affect the systems of living things concludes that shift-work constitutes an independent risk factor for impaired glucose metabolism.

Modern industrialisation, consumer expectations and globalisation have led to the widespread adoption of round-the-clock operations in many industries throughout the world. This has resulted in an increased proportion of the population routinely engaged in shift work.

An association between shift work and cardiovascular diseases has been widely reported. Disturbed circadian rhythms, sleep and lifestyle problems and increased stress have been implicated as possible risk factors for many serious diseases. This study highlights a previously unrecognised risk for the millions of people who work atypical shift schedules.

“It has long been known that sleep debt has a harmful impact on carbohydrate metabolism and endocrine function,” says Michael Smolensky, Co-Editor of Chronobiology International. “It is therefore reasonable to expect that shift work may influence glucose tolerance. Alternating between day and night shifts - resulting in continuous disruption of the body’s circadian rhythms - has been shown by this study to be damaging to the health of workers.

“The main finding of this study is that shift work has a significantly detrimental effect on levels of hemoglobin A1c, which is used as an index of glucose metabolism. The effect was similar to that seen with well-established risk factors, such as age and BMI.”

The study’s findings are consistent with two cross-sectional studies on glucose tolerance that reported a significant relationship between shift work and the development of diabetes mellitus.

“Unfortunately, shift work seems to be a necessity of modern life,” continues Smolensky. “However, intelligent development of more health-preserving shift schedules together with efficient health screening and regular check-ups may be of considerable benefit in maintaining the health of this vulnerable group of workers.”