Meals of the day can help night shift workers regulate blood sugar levels – archyde

What are the effects of eating at night instead of during the day? New research focused on simulating night shift work may have implications for people who eat at atypical times -; such as those who suffer from jet lag, circadian rhythm insomnia, or who tend to sleep late on the weekends.

A study by investigators at Brigham and Women’s Hospital shows that eating during the night can lead to glucose intolerance, while restricting meals to the day can help regulate blood sugar levels. Nightly eating appeared to be causing a misalignment between the body’s central and peripheral circadian “clock” -; natural timepieces that regulate physical, mental and behavioral changes over a 24-hour cycle. The researchers’ results are published in Scientific advances.

These results suggest that the timing of meals 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. While the central circadian “clock” was still on Boston time, the endogenous circadian glucose rhythms suggest that some peripheral “clocks”, perhaps that of the liver, had shifted dramatically to a time zone in Asia.”

Frank AJL Scheer, PhD, MSc, Study Co-Corresponding Author, Medical Department and Director of the Medical Chronobiology Program in the Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital

Glucose intolerance leads to high glucose levels and often precedes type 2 diabetes mellitus (T2DM), a condition in which the body is less able to absorb sugar from the bloodstream into its tissues. T2DM is prevalent among night shift workers who typically sleep during the day and eat at night. Previous laboratory studies showed elevated blood sugar levels in both non-shift workers and shift workers doing simulated night work, said co-author Sarah L. Chellappa, MD, PhD, formerly from the Medical Chronobiology Program and now from the Department of Nuclear Medicine at the University of Cologne. They added that although shift workers are often exposed to meals at the wrong time, they are not necessarily “immune” to their side effects.

This study, a randomized controlled trial, enrolled 19 healthy young participants who underwent a 14-day controlled laboratory protocol. During the study, participants stayed awake for 32 hours in a tightly controlled, dimly-lit environment in which they maintained a constant posture, ate identical snacks every hour, and had no timing. Conditions that are part of a constant routine protocol.

Participants then went through simulated night work and followed one of two meal plans: one group ate during the night to simulate a typical night shift schedule, while the other group ate during the day, thus adjusting their meal plan to the ~ 24-hour cycle of the central circadian “Clock”. Participants then followed a second, constant 40-hour routine protocol to assess the after-effects of meal plans on their endogenous circadian rhythms.

According to the study, participants who ate at night showed increased blood sugar levels, while those who only ate during the day had no significant changes. In addition, nocturnal food consumption decreased pancreatic beta cell function compared to no observable changes in those who only eat during the day.

Beta cells produce insulin, a hormone that transports glucose to tissues in the body. In addition, nighttime eating caused a misalignment between the central circadian “clock,” estimated from the endogenous circadian rhythm of core body temperature, and the endogenous circadian glucose rhythms. In stark contrast, when participants only ate meals during the day despite their poor sleep, these rhythms stayed aligned.

“Of the participants studied, those with the greatest disruption to their circadian system – quantified here as the misalignment between their central circadian ‘clock’ and their endogenous circadian glucose rhythm – showed the greatest impairment in glucose tolerance,” said Scheer.

The study’s take-home message shows that eating during the day, despite sleeping at the wrong time, maintains internal circadian alignment and prevents glucose intolerance. The authors point out that more research needs to be done to find practical interventions to translate shiftworker’s eating into real life.


Journal reference:

Chellappa, SL, et al. Eating during the day prevents internal circadian misalignment and glucose intolerance during night work. Scientific advances.


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