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Shift workers who suffer ‘body-clock’ disruption, as a result of not getting enough sleep and at the wrong time of the day, could be at greater risk of developing diabetes and associated weight problems, researchers have found.
The US study, which is published in the journal Science Translational Medicine, involved 21 people, whose lives, including meals and sleep periods, were controlled under laboratory conditions.
At the start of the trial, the test subjects were allowed 10 hours’ sleep at night. This was followed by three weeks of disruption to their sleep patterns and body-clock rhythms. Not only was the day artificially extended to 28 hours but participants were only allowed to sleep for 6.5 hours – equivalent to 5.6 hours in a normal day. Dim-light conditions also became the norm to prevent their body clocks from re-adjusting.
Under these conditions, blood sugar levels among the test subjects significantly increased immediately after they had food and between meals. Researchers found that lower levels of insulin – the hormone that normally controls blood sugar – were produced. The reduced metabolic rate among participants translated into a significant increase in weight, assuming that they had been exposed to the same sleep-disruption conditions for a year.
The findings led the researchers to call for more action to reduce the health impact of shift working, which has also been linked to breast cancer, prostate cancer, non-Hodgkin’s lymphoma, fatigue, heart-disease risk factors, and pregnancy problems.
Commenting on the study, Dr Matthew Hobbs, head of research at Diabetes UK, said: “This is an interesting study, which shows that under extreme conditions, involving sleep deprivation and ‘tricking’ the body clock, participants produced less insulin and therefore had higher blood glucose levels than when they were able to sleep normally and live according to normal daily rhythms.”
However, he cautioned that the laboratory-testing environment cannot ever replicate real-world conditions, and stressed that the low number of people who participated in the trial rendered the results ‘scientifically’ invalid.
He explained: “In this study, in order to trick the body clock, participants lived for three consecutive weeks in a dimly-lit lab with no clocks, no windows, and no other indicators of time. For those three weeks, they slept for 6.5 hours per 28 hours. Clearly, this does not equate to the normal experience of shift workers who are able, for example, to use bright lights when not sleeping. The study also involved only 21 people.
“For these reasons, it is not possible to conclude that the findings would translate to real conditions for the wider public. What we can say for certain is that by undertaking regular exercise and eating a healthy, balanced diet, everybody, including shift workers, can reduce their risk of developing Type 2 diabetes.”