Late-night eating may add to diabetes and obesity risk for shift workers

The health impacts of disruptions to our body clocks, the type regular shift workers might endure, are becoming clearer on the back of research uncovering links to heart disease and impacts on metabolism, among other effects. A new study has drilled into the relationship between the timing of our meals and the body's blood glucose levels, finding that those chowing down after dark may be at greater risk of diabetes and obesity.

The body's natural sleep-wake cycle, known as our circadian rhythm, is increasingly being found to play a role in all kinds of health outcomes. Last month, for example, we looked at a study detailing new mechanisms within heart cells that govern a shift in cardiac activity over 24-hour periods, offering clues as to why shift workers are at higher risk of heart trouble.

Some studies have shown how irregular sleep patterns can have a similar effect, while others have shown they can drive up the risk of developing metabolic disorders such as hypertension, obesity, and diabetes. Shining further light on the topic are the results from a small clinical trial involving 19 young and healthy subjects, all of whom were made to keep hours that simulated night work conditions.

The cohort was divided into two groups, with either a regular daytime eating schedule, or a nighttime eating schedule replicating that of a typical night worker. This took place across a 14-day period, and was designed to explore whether the increased risk of diabetes endured by night workers can be countered, to some degree, by a daytime eating schedule. Assessing blood glucose levels afterwards revealed a marked difference between the two groups, with levels of those who ate at night found to be an average of 6.4 percent higher.

“This is the first study in humans to demonstrate the use of meal timing as a countermeasure against the combined negative effects of impaired glucose tolerance and disrupted alignment of circadian rhythms resulting from simulated night work,” says study leader Frank A.J.L. Scheer, professor of medicine at Harvard Medical School.

The results point to a possible lifestyle intervention to lower the risk of diabetes among night workers, but the scientists say that the mechanisms at play are complex. They believe at the root of the issue is a circadian misalignment, or a mistiming between the central circadian clock in the brain's hypothalamus and the behavioral sleep/wake and eating/fasting cycles, leading to the observed effects on blood glucose.

“This is a rigorous and highly controlled laboratory study that demonstrates a potential intervention for the adverse metabolic effects associated with shift work, which is a known public health concern,” says Marishka Brown, Ph.D., director of the National Heart, Lung, and Blood Institute's National Center on Sleep Disorders Research. “We look forward to additional studies that confirm the results and begin to untangle the biological underpinnings of these findings.”

The research was published in the journal Science Advances. 

Source: National Institutes of Health