Shift Work Raises Risk of Diabetes

Scientists in the United States say shift workers getting too little sleep at the wrong time of the day could be increasing their risk of diabetes.

They have found that changes to normal sleep means the body is unable to control sugar levels.

For three weeks researchers created an environment where the participants in the trial felt constantly jet lagged.

By the end, some of the 21 participants had significantly increased sugar levels and were classified as pre-diabetic.

Lead researcher Dr Orfeu Buxton, from the Harvard Medical School, says previous studies have shown night and shift workers have a higher probability of having obesity or diabetes, but have not identified the mechanism for how it happened.

"What we found in this study was that when we induced circadian disruption (activity and rhythm disruption) in the laboratory for three weeks we could alter glucose metabolism in a way that would predict elevated diabetes risk," he said.

"[It suggests] that the mechanism by which night workers have increased diabetes risk is an insufficient release of insulin by the pancreas."

Dr Buxon says the researchers are not sure why the pancreas is not responding.

"We gave identical meals when subjects were rested and when they had recovered from the circadian disruption and sleep restriction and they did recover, but the pancreas simply failed in response to that identical meal to secrete sufficient insulin to hold glucose levels in the normal range," he said.

Jet lagged

Dr Buxon says the study simulated travelling west through four times zones each day for three weeks.

"We studied 21 individuals who had a base line period where they were fully rested, we topped off their sleep very carefully and then we submitted the subjects in very controlled diet and activity and light and dark conditions to circadian disruption - we did that by scheduling the sleep and wake and light and dark and meals to occur four hours later each day," he said.

Dr Buxon says his study shows there is an urgent need for intervention.

"There are two general types of strategies for avoiding these problems or preventing them," he said.

"One would be adapting better to night work, so using timing of light and dark and meals to avoid some of the more severe disruption.

"The other is to get better sleep during the day. So one approach is to get sleep during that day that's in an environment that's dark, silent and cool and of course, turn off the phone."