December 9, 2021

Daytime Meals May Improve Health of Night Shift Workers, Study Finds

The results of a small clinical trial funded by the National Heart, Lung, and Blood Institute (NHLBI), a part of the National Institutes of Health (NIH), indicate that eating meals during the nighttime—as many night shift workers do—may significantly increase glucose levels. Higher glucose levels are a risk factor for diabetes, a condition that shift workers have been found to experience at higher rates, an NIH press release explains. The findings of the new study indicate that eating during the daytime may prevent boosted glucose levels associated with nighttime shift work. Researchers describe the study as the first 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.” These findings could inspire interventions to improve the health of shift workers, including grocery stockers, hotel workers, truck drivers, and first responders, the study authors suggest.

Researchers with the Medical Chronobiology Program at Brigham and Women’s Hospital in Boston, Massachusetts, assigned 19 healthy participants to a two-week protocol involving simulated night work conditions. One group of participants was randomly assigned to eat during the nighttime while the others ate meals during the day. Then, the researchers evaluated the effects of the meal schedules on participants’ circadian rhythms, the body’s internal process that regulates most of its functions, including sleep and metabolism, according to a roughly 24-hour schedule. Participants who ate at night experienced, on average, a 6.4 percent increase in glucose levels during their simulated night work routine, while participants who ate during the day did not show a significant increase in glucose levels.

While the mechanisms behind these effects are thought to be complex, the study’s authors believe that the increase in glucose levels associated with a nighttime meal schedule may result from misalignment between the body’s central circadian “clock,” a biochemical system controlled in the hypothalamus in the brain; peripheral “clocks” located throughout the body; and behavioral cycles such as sleeping and eating routines. As these clocks govern the body’s chemical cycles, this study shows that, in particular, misalignment between the circadian clock and eating routines increases the body’s glucose levels. Eating during the daytime may encourage better alignment between the body’s central and peripheral clocks, the findings suggest.

“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,” said Marishka Brown, PhD, director of NHLBI’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.”

NIH notes that future studies with real-life shift workers in their typical work environments will be required to translate the study’s findings into practical and effective interventions.

For more information and a link to the study, refer to the NIH news release.