Eating at night may increase health risks for shift workers, a new study finds

Eating at night may increase health risks for shift workers, a new study finds
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A small clinical trial by the National Institutes of Health has found that eating at night can increase glucose levels, linked with nocturnal work life.

The findings could lead to novel behavioural interventions aimed at improving the health of shift workers that are eating at night with previous studies finding they could be at an increased risk for diabetes, heart disease, and obesity.

In the new study, researchers noted that the trial is the first to demonstrate the beneficial effect of this type of meal timing intervention in humans. It is published online in the journal Science Advances.

The effects of eating at night on bodily functions

The study involved 19 healthy young participants (seven women and 12 men). After a preconditioning routine, the participants were assigned a 14-day controlled laboratory protocol involving simulated night work conditions with one out of two meal schedules. One group mimicked a meal schedule typical amongst night workers, and the other group ate during the daytime.

The researchers evaluated the effects of these meal schedules on their internal circadian rhythms, which is the internal process that regulates the sleep-wake cycle and the 24-hour cycle of bodily functions such as metabolism.

Clinical trial outcomes

The researchers found that eating at night boosted glucose levels yet, restricting meals to the daytime prevented this effect. Specifically, the control group eating at night saw a 6.4% increase on average in glucose levels, whilst those who ate during the day showed no significant increase.

“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,” said study leader Frank A.J.L. Scheer, PhD, professor of medicine at Harvard Medical School and director of the Medical Chronobiology Program at Brigham & Women’s Hospital in Boston.

The researchers noted that the mechanisms behind the observed effects are complex. They believed that eating at night affected glucose levels during the simulated night work due to circadian misalignment. That corresponds with the mistiming between the central circadian “clock” (located in the brain’s hypothalamus) and behavioural sleep/wake, light/dark, and fasting/eating cycles, which influences the peripheral “clocks” throughout the body.

The current study shows that the mistiming of the central circadian clock with the fasting/eating cycles play a key role in boosting glucose levels. Additionally, the findings suggest that the beneficial effects of daytime eating on glucose levels during simulated night work may drive a better alignment between these central and peripheral “clocks”.

“This study reinforces the notion that when you eat matters for determining health outcomes such as blood sugar levels, which are relevant for night workers as they typically eat at night while on shift,” said the study co-leader Sarah L. Chellappa, M.D., PhD, a researcher in the nuclear medicine department at the University of Cologne, Germany. Chellappa formerly worked with Scheer in Brigham & Women’s Medical Chronobiology Program.

However, to translate these findings into practical and effective meal timing interventions, the researchers said more study is needed, including real-life shift workers in their typical work environment.




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