A ‘Dented’ Internal Clock Provides Insight Into Shift Workers’ Weight Gain and Diabetes

AHA Publisher — Fri, 29 Oct 2021 07:00:27 +0000

Perelman School of Medicine at the University of Pennsylvania via Newswise – PHILADELPHIA— A study of “dented” internal clocks seems to have provided evidence for a theory as to why people who work late or irregular hours are susceptible to weight gain and diabetes. High rates of shift workers gain weight and develop diabetes, which has been attributed to a mismatch between their internal clocks and their schedules, so researchers from the Perelman School of Medicine at the University of Pennsylvania created a related mismatch by altering the function of a molecule within the brains of mice that shortened their circadian rhythms from 24 to 21 hours. These mice gained more weight, had higher blood sugar, and fattier livers, all of which were corrected by changing their environment to a 21-hour “day.” “When the external world doesn’t match the internal body’s cycles, metabolism pays the price,” said the study’s senior author, Mitchell A. Lazar, MD, PhD, the director of Penn Medicine’s Institute for Diabetes, Obesity, and Metabolism, and the Ware Professor of Diabetes and Metabolic Diseases. “We saw this in our study, and we believe that this happens similarly when people work odd hours that don’t align with how human bodies are wired.” Published today in Science Advances, the researchers led by Lazar and primary investigator Marine Adlanmerini, PhD, a post-doctoral researcher in Lazar’s lab, sought to explore circadian desynchrony, a theory in which a disruption or alteration to a person’s innate, internal clock leads to poor outcomes. Shift workers – those who may work long hours, overnight, or with irregular rest periods in between work – are subject to this, which could be why they appear to be at higher risk for obesity, diabetes, and metabolic diseases including having a liver that retains more fat. So to explore whether circadian desynchrony is a viable explanation for this, the researchers removed certain molecules called REV-ERB, which reside in the brain cells of mice, and seem to control the body’s internal clock, holding it around 24-hour cycles. When REV-ERB was deleted, it caused the mouse body clocks to run roughly three hours shorter, which the researchers determined by tracking their regular sleep/awake pattern. While their body clocks ran faster, some of these mice were kept in a typical day’s 24-hour cycle, with 12 hours of light and 12 of dark. Those mice, when on their regular diet, were able to keep their weight in check. But when given a diet with higher contents of fat and sugar – a diet not unfamiliar to the typical American – they gained more weight and had more adverse conditions, like diabetes and fatty liver. Moreover, the mice who still had REV-ERB but were given the high-fat and sugar diet did not have the same high amounts of poor outcomes. “One potential explanation is that the internal clock of the mice missing REV-ERB was running at odds with the 24-hour day, which led to metabolic stress on the body,” Lazar said. A way that was “fixed” was when the researchers adjusted the length of the mice’s “day” in the lab to match their malfunctioning internal clock: 21-hour days with 10.5-hour cycles of light and dark to match their 21-hour internal clock. When this happened, the mice with the altered clocks no longer were as susceptible to the ill-effects of the unhealthy diet. That correction seemed to fall in line with the circadian desynchrony theory: Once the internal clock and the day lined up again, metabolism appeared to operate at its normal, healthy rate. “This may be a lesson for how to prevent or reduce obesity and diabetes in shift workers,” Lazar explained. “For example, timing of meals to better match the shift worker’s own clock could be of benefit. That would also be consistent with a number of studies in mice and people that have suggested that eating at specific times of day may improve weight control and metabolism.” Moving forward, Lazar, Adlanmerini, and their team feel that potentially finding biomarkers which could be tested for and indicate how a person’s internal clock is running would be key. “Information like that could then be matched to decisions about when to eat, much as blood sugar monitoring can help a diabetic understand when they should be taking more insulin,” said Lazar. To read the original article click here.

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Spring Forward Your Clock, But Don’t Fall Back On Your Sleep

AHA Publisher — Mon, 15 Mar 2021 07:00:19 +0000

University of Texas Health Science Center at Houston via Newswise – Daylight saving time [was yesterday], and as many look forward to the longer and warmer days that accompany this time change, losing an hour of sleep can have you feeling out of sorts. An expert with The University of Texas Health Science Center at Houston (UTHealth) shares why it’s important to prepare our bodies for the time change. “Daylight saving time is really hard on our internal clock,” said Kristin Eckel-Mahan, PhD, assistant professor in the Center for Metabolic and Degenerative Diseases at McGovern Medical School at UTHealth. “Our bodies function off our circadian rhythm, which works in sync with the outside light-dark cycle. So, when we advance our clock one hour it can really impact how our bodies react.” Although it is only an hour, Eckel-Mahan says it is difficult for our internal or circadian clock to make the sudden change. The circadian rhythm is the 24-hour cycle that is part of the body’s internal clock, and a critical part of the circadian rhythm is our sleep-wake cycle. The sleep-wake cycle is our daily pattern that determines when it’s time to sleep and when it’s time to be awake. To prepare for the upcoming time change, Eckel-Mahan recommends to begin gradually adjusting your sleep routine one week ahead of daylight saving time. “If you begin to adjust your sleep-wake cycle by just 10 minutes a day for the six days leading up to daylight saving time, you can really ease yourself into the hour time change. Doing this can be very helpful in adjusting your internal clock,” Eckel-Mahan said. Light plays a significant role in adjusting our sleep-wake cycles. According to Eckel-Mahan, dimming the lights earlier to adjust to the upcoming time change and exposing yourself to brighter light in the morning can be a very effective way to shift your circadian rhythm to maintain a good night’s rest. In addition to adjusting your sleep schedule, Eckel-Mahan suggests changing what time you eat. “While light is the primary driver of our brain clock, food is a very strong driver of several peripheral organs. If you are eating late at night, even in dim light, it will send a different cue to your organs like your liver, or your muscles. So, I would suggest cutting the food off a little earlier and get it in sync with the adjustments you make to your sleep, because that is something that will really affect your internal clock,” she said. Sleep plays an important role in cognition and biological processes such as restoring energy to the body and the removal of waste products from brain cells. “Sleep is incredibly important to your health, and just as important as eating healthy and exercising,” Eckel-Mahan said. “Research shows poor sleep can put you at an increased risk of unhealthy weight gain, heart disease, and diabetes.” Practicing these changes with the entire family can be beneficial to children and even pets. This article has been modified. To read the original article click here.

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A ‘Dented’ Internal Clock Provides Insight Into Shift Workers’ Weight Gain and Diabetes

Spring Forward Your Clock, But Don’t Fall Back On Your Sleep