Daytime meals may lower health risks linked to night shift work.
What are the long-term consequences of eating at night rather than during the day? When it comes to eating, individuals who are jet-lagged or suffer from circadian rhythm sleep disorders might benefit from new research that mimics night shift work.
A small clinical trial funded by the National Institutes of Health discovered that eating late at night, as many shift workers do, can raise glucose levels, whereas eating just during the day can prevent the higher glucose levels now associated with nocturnal work.
The findings could lead to novel behavioral therapies aimed at improving the health of shift workers, such as grocery stockers, hotel workers, truck drivers, first responders, and others, who have been linked to an elevated risk of diabetes, heart disease, and obesity in previous research.
The new study, which the researchers claim is the first to show that this kind of meal timing intervention is useful for humans, is published online in the journal Science Advances.
“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 Dr. Marishka Brown, director of the 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.”
The researchers recruited 19 healthy young people for the study (seven women and 12 men). The participants were randomly allocated to a 14-day controlled laboratory regimen combining simulated night work conditions with one of two meal plans after a preconditioning process. One group ate at night to simulate the meal routine of night workers, whereas the other group ate during the day.
After that, the researchers looked at how various meal regimens affected their internal circadian rhythms. That’s the internal mechanism that controls not only your sleep-wake cycle, but also the 24-hour cycle of nearly all of your biological functions, including metabolism.
The researchers discovered that eating late at night increased glucose levels, which is a risk factor for diabetes, whereas eating just during the daytime reduced this impact. Specifically, during the simulated night work, average glucose levels for those who ate at night climbed by 6.4 percent, while those who ate during the daytime exhibited no significant increases.
“These results indicate that meal timing was primarily responsible for the reported effects on glucose tolerance and beta-cell function, possibly due to the misalignment of central and peripheral ‘clocks’ throughout the body,” says study leader Dr. Frank A.J.L. Scheer, from Brigham & Women’s Hospital in Boston.
“While the central circadian ‘clock’ was still on Boston time, the endogenous circadian glucose rhythms suggest that some peripheral ‘clocks,’ as perhaps those in the liver, had dramatically shifted to a time zone in Asia.”
High glucose levels are caused by glucose intolerance, which frequently precedes type 2 diabetes mellitus (T2DM), a condition in which the body’s ability to absorb sugar from the bloodstream into its tissues is impaired.
Night shift workers, who sleep during the day and eat at night, are more likely to develop T2DM. According to co-corresponding author Dr. Sarah L. Chellappa, previous laboratory studies showed increased blood glucose levels in both non-shift workers and shift workers who underwent simulated night work. While shift workers are routinely exposed to mistimed meals, they are not necessarily “resistant” to their negative effects, they warned.
The mechanisms behind the reported impacts, according to the researchers, are complicated. They believe that circadian misalignment is to blame for the impact of mistimed meals on glucose levels during simulated night work.
The misalignment of the central circadian “clock” (placed in the hypothalamus of the brain) with behavioral sleep/wake, light/dark, and fasting/eating cycles, which can influence peripheral “clocks” throughout the body, correlates to this.
Mistiming of the central circadian clock with the fasting/eating cycles, according to the current study, is a crucial factor in raising glucose levels.
The findings also suggest that the favorable benefits of daytime eating on glucose levels during simulated night labor could be attributed to a better synchronization of 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,” adds the study co-leader Dr. Sarah L. Chellappa.
The researchers emphasized that further research is needed, including with real-world shift employees in their regular work setting, in order to make these findings applicable and useful.
Source: 10.1126/sciadv.abg9910
Image Credit: shutterstock
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