Why is it healthier to eat during the day if you work at night?

According to the study authors, the findings could lead to new behavioral interventions aimed at improving the health of shift workers (food replenishers, hotel workers, truck drivers, first responders and others), which, according to studies previous, are at increased risk for diabetes, heart disease, and obesity.

The new study, which researchers say is the first to demonstrate the beneficial effect of this type of intervention on meal timing in humans, has been published online in the journal Science Advances and funded primarily by the National Institute. of the Heart, Lungs and Blood (NHLBI), which is part of the NIH.

“Is about a rigorous and highly controlled laboratory study that demonstrates a possible intervention for the adverse metabolic effects associated with shift work, which is a known public health problem, ” explains Dr. Marishka Brown, director of the NHLBI’s National Center for Sleep Disorders Research. We look forward to further studies that confirm the results and begin to unravel the biological rationale for these findings. ”

For the study, the researchers recruited 19 young, healthy participants (seven women and 12 men). Following a preconditioning routine, participants were randomly assigned to a 14-day controlled laboratory protocol that included simulated night work conditions with one of two meal times. One group ate at night to mimic the typical meal schedule of night workers, and another group ate during the day.

They then evaluated the effects of these meal times on your internal circadian rhythms. This is the internal process that regulates not only the sleep-wake cycle, but also the 24-hour cycle of virtually all aspects of bodily functions, including metabolism.

Glucose level rise

They found that late night meals increased glucose levels –a risk factor for diabetes– while restricting meals per day avoided this effect. Specifically, the mean glucose levels of those who ate at night increased by 6.4% during simulated night work, while those who ate during the day did not show significant increases.

“This is the first human study to show the use of meal times as a measure to counteract negative effects combined effects of impaired glucose tolerance and altered circadian rhythms resulting from sham night work, “says study leader Dr. Frank AJL Scheer, professor of medicine at Harvard Medical School and director of the Medical Chronobiology from Brigham & Women’s Hospital in Boston.

The researchers note that the mechanisms underlying the observed effects are complex. They believe that the effects of nighttime meals on glucose levels during simulated night work are due to circadian mismatch.

Circadian ‘clock’

That corresponds to the mismatch between the central circadian “clock” (located in the hypothalamus of the brain) and the sleep / wake, light / dark, and fast / food cycles of behavior, that can influence the peripheral “clocks” of the whole body.

The study shows that, in particular, the central circadian clock lag with the fast / food cycles plays a key role in increasing glucose levels. The work further suggests that the beneficial effects of daytime feeding on glucose levels during simulated night work may be due to a better alignment between these central and peripheral “clocks”.

“This study reinforces the notion that timing is important in determining health outcomes, such as blood sugar levels, which are relevant for night workers, as they tend to eat at night while on shift, “explains study co-leader Dr. Sarah L. Chellappa, a researcher in the department of nuclear medicine at the University of Cologne (Germany).

To translate these findings into practical and effective meal timing interventions, the researchers caution that more studies are needed, even with real-life shift workers in their typical work environment.